2001 Eldorado Overheating

[hms200]

ok, now give us a brief summary of your problem again

Is it boiling over?

What are the temp ranges?

Are there any leaks?

Do you smell coolant?

Does the needle spike above half way and how far

What have you done?, there are a few here we are working with, did you replace the tank recently or am I confusing you with someone else

Refresh our memories at this point, in a brief organized fashion

Ok thx BBF...here is the step-by-step update I posted the other day...prior to the latest chatter today.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

LATEST UPDATE...will document latest activity step by step...see what you think.

1. Installed the new coolant tank and refilled coolant using 50/50 mix.

2. Performed another highway test drive @ 65-85 mph.

3. Normal temp reading is typically reading just beyond TDC (high side of normal range).

4. During highway speeds I observed TWO momentary temp rises to a point between 225 and 245 degree ticks, but then quickly returned back to its normal. Huh??

5. No boiling or surge from overflow tube during test drive or upon returning to garage...no coolant loss that I could detect or smell.

6. After cooling for a bit I checked coolant level in tank. Topped off the tank with ~1/4 gal coolant. To be expected for a new fill-up, even with purge line setup or would one suspect it boiled out on highway?

7. Just for grins, I performed another blue water block test again, this time using a different spare bottle of blue chemical I had onhand since some suggested what I used last time might be old. Still got no positive results whatsoever. Guess my spare bottle could be old as well. Oh well...was just a shot in the dark.

8. Pulled DTC's (SES light's been on since I purchased the car) since I need to go get emissions test - Only "Current" codes were P0171 and P0174...checked for vacuum leaks but none found.

9. Cleared all DTC's to turn off SES light and took vehicle for emissions test (needed registration - only had temp tag).

10. Vehicle passed emissions with flying colors.

11. Registered vehicle before temp tags expired on me.

12. Took vehicle to a nearby shop and inquired about what tests they could perform for validating HG's. Was told 1) Cooling System Pressure Test, 2) Smoke up the tailpipe test (said test would show smoke anywhere that exhaust is escaping, including into coolant via a head gasket leak). He did say it may or may not prove anything with HG's since heads may be leaking only under heavy load. They didn't have a test to verify exhaust gases in the cooling system...just the pressure and smoke tests.

13. Shop strongly recommended that I replace water pump as my next step. Ok, of course. They said that failed impeller blades can cause the flux of temp as I described, without any of the other typical classic outward signs of a failed water pump, due to poor coolant flow...obviously, but flux quickly as a result? He showed me diagram of the pump itself (very strange design, wow) and advised that I'd need a special OEM tool to disengage the spring loaded pump cylinder from housing if I'm to replace it myself. Is there no other way to verify proper coolant movement short of replacing the water pump or removal to inspect the blades??

14. Well, left the shop still scratching my head, still thinking I need a specific exhaust gases in coolant test as my next step...so on to a radiator shop I suppose. Couldn't a flaky temp sensor cause the strange momentary temp flux I observed? Seems very strange and unlikely that a sudden climbing temp could/would recover back to normal so quickly as I had observed...within ~10-15 seconds I'd say. All my past experience has been that once overheating begins it's very difficult to reverse that movement on the fly...certainly wouldn't expect it to reverse so quickly. Odd or reasonable??

15. On drive back home the SES light returned...no overheating and no coolant loss. Pulled the codes and the P0171 and P0174 codes have returned.

16. Coolant level is still fine, with no boiling/surging and no overheating during the city driving and emissions test.

As for vacuum leaks, I cannot spot any suspects so far from just manual viewing, probing around and listening for hiss. I did correct several bad hose connections earlier that I had stumbled across during other troubleshooting (compression test) activities, associated with crankcase ventilation tube from front valve cover to throttle body, but nothing recent. Have not yet attempted to troubleshoot any other common possible causes of the two codes appearing together other than I do know air filter and filter canister are clean, intake hose is intact (no cracks/splits) and the throttle housing is clean and clear from what I had observed earlier. I also did check the bolts on air intake manifold to ensure snug...they are. Could still be a gasket leak there though I suppose.

So that's where things stand as of tonight folks.

I'll be attempting to find a garage or radiator shop that offer tests that I feel are appropriate. Smoke test up the tail pipe sound appropriate to anybody here as the next test? Didn't sound right to me...BBF said multiple times, get a test to verify gases in the coolant. I could change the temp sensor I suppose (it's cheap I think)...but that's chasing problem thru more trial and error, which I'm trying hard to resist. Think I should?

HMS

[Ranger]

When I questioned the momentary temp flux he said that is completely normal for the Northstar. Really?? So here's they key question for all you REALLY smart Northstar guru's out there. The guy stated that the Northstar uses its cylinder shut-down technology to control heat in the "normal" course of operation, and that's exactly what I spotted with the momentary temp spike with rapid recovery. Really??

Nonsense. Cylinder shut down or "limp home mode" ONLY occurs at 265 degrees when the engine is in a severe overheat situation. NEVER as a normal cooling operation.

6. After cooling for a bit I checked coolant level in tank. Topped off the tank with ~1/4 gal coolant. To be expected for a new fill-up, even with purge line setup or would one suspect it boiled out on highway?

7. Just for grins, I performed another blue water block test again, this time using a different spare bottle of blue chemical I had onhand since some suggested what I used last time might be old. Still got no positive results whatsoever. Guess my spare bottle could be old as well. Oh well...was just a shot in the dark.

Doing the block test AFTER topping off the surge tank with fresh coolant will almost always give you a negative result. Best to do it after an overheat situation, BUT you still might get a negative IF you are in the early stages of a HG failure where only small amounts of exhaust gases are entering the system.

They said that failed impeller blades can cause the flux of temp as I described, without any of the other typical classic outward signs of a failed water pump, due to poor coolant flow.

Theoretically possible, but very unlikely.

Is there no other way to verify proper coolant movement short of replacing the water pump or removal to inspect the blades??

I think your purge line test verified coolant flow, didn't it?

Couldn't a flaky temp sensor cause the strange momentary temp flux I observed?

Again, theoretically possible, but I can't recall ever hearing of that being the case.

Personally, It's not bad right now so I'd just drive it. If it is the HG, it WILL get worse and remove all doubt.

[hms200]

Thx Ranger...I'll just make it my daily driver for local travel for a bit and see what happens, or until I have further testing performed.

I performed that latest block test attempt before adding rhe coolant in the tank, while car was still warm. Sorry, I documented that step out of actual order.

[BodybyFisher]

This was a very good summary thanks

You said this

During highway speeds I observed TWO momentary temp rises to a point between 225 and 245 degree ticks, but then quickly returned back to its normal. Huh??

When did that occur?, after the new tank? It is possible that if this occurred after putting in the tank, the system needed to stabilize.

As others have said, DO NOT replace the water pump, it is basically indistructible, NO WAY the impellers corroded away, they are misinformed on this water pump.

Check again to make sure that the water pump belt tensioner is free and NOT binding at all. Overheating at highway speeds can be caused by the water pump belt slipping

At highway speeds ram air is blowing through the radiator so any problems with the cooling fans is out of the question

What is the status of your radiator?, don't you have one sitting there waiting to go in?

I would think that if you were getting engine coolant temp sensor problems you would set a code

These are the codes you can get from the engine coolant temp sensor

P0115 - Engine Coolant Temperature (ECT) Sensor Circuit

P0116 - Engine Coolant Temperature (ECT) Sensor Performance

P0117 - Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

P0118 - Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

P0119 - Engine Coolant Temperature Circuit Intermittent

So other than the spikes, does it appear to be burning up?

Keep driving it and see if it settles down, but answer the questions I raised in this post

[BodybyFisher]

Could the lower hose be collapsing from suction? Try squeezing it to see if its soft

[hms200]

My responses below ...thx much!

During highway speeds I observed TWO momentary temp rises to a point between 225 and 245 degree ticks, but then quickly returned back to its normal. Huh??

When did that occur?, after the new tank? It is possible that if this occurred after putting in the tank, the system needed to stabilize.

[HMS REPLY: It happened during highway drive test after replacing tank, about 8 miles into the voyage, and 2nd time about 2-3 miles later...going between 70-75 mph I believe. I then turned around and headed back out of fear that it was about to seriously overheat on me. I altered my speed on return to between 65-70 mph...needle never moved again on me though.]

As others have said, DO NOT replace the water pump, it is basically indistructible, NO WAY the impellers corroded away, they are misinformed on this water pump.

[HMS REPLY: Thx for the validation on bugus info. No plans to change pump...already rejected that diagnosis as well, as did the shop in Parker also that I spoke with today. He was attempting to shotgun the issue at my expense...far too typical these days with shops, with far too many uninformed, helpless victims to that I'm sure...grrr.]

Check again to make sure that the water pump belt tensioner is free and NOT binding at all. Overheating at highway speeds can be caused by the water pump belt slipping

[HMS REPLY: I will check again. No signs of belt being in distress though. Perhaps at this point I should physically pop off the belt for closer inspection?]

At highway speeds ram air is blowing through the radiator so any problems with the cooling fans is out of the question

What is the status of your radiator?, don't you have one sitting there waiting to go in?

[HMS REPLY: Yep, I have the new radiator still sitting to the side, boxed up with receipt so I can return it if determined to not be needed. Whay do you ask...suspecting possible radiator blockage perhaps? The multiple draining and fill-ups I've done on coolant all flowed really well, out and in...no slow gurgling or any such if that may add any light?]

I would think that if you were getting engine coolant temp sensor problems you would set a code

These are the codes you can get from the engine coolant temp sensor

P0115 - Engine Coolant Temperature (ECT) Sensor Circuit

P0116 - Engine Coolant Temperature (ECT) Sensor Performance

P0117 - Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

P0118 - Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

P0119 - Engine Coolant Temperature Circuit Intermittent

So other than the spikes, does it appear to be burning up?

[HMS REPLY: Zero such codes have appeared, either current or history...nada. Nope, it doesn't at all seem to be burning up...appears to be running like a champ, other than slight idle stumble at times, more noticable when cold than one hot. I suspect that may be associated with whatever is throwing the two codes I reported before, P0171 & P0174 in current that did reappear later after I cleared them...thankfully AFTER the emissions test rather than DURING. ]

Could the lower hose be collapsing from suction? Try squeezing it to see if its soft

[HMS REPLY: The lower hose isn't soft...feels fine. I can also feel the inner wire spring...intact all the way from radiator to thermostat housing. Saw the end of it also when I replaced the thermostat and it looked in excellent condition...no rust or crud was present on that end.]

HMS

[hms200]

Here is max temp reading I believe during both momentary spikes...

[BodybyFisher]

The guru used to say that high speed overheating could be caused by a slipping water pump belt, definately check the belt. Look for a shine on the belt, from slipping. Check the pulley for roughness or locking, and check the tension arm to see if its binding AT ALL.

Good you checked the lower hose, and the spring is intact

One thing you said concerns me, "appears to be running like a champ, other than slight idle stumble at times, more noticable when cold than one hot"

This cold 'miss' is what I got when my head gasket was bad in the beginning.... not a good sign. Again, go for a test, now that the coolant has been in for awhile. If your head gasket is beginning to go bad, it could be the beginning, I drove mine for a year, watching the temp needle, but it ran 217 instead of 205 during that year.

The P0171 and P0174 is a lean mixture on both banks, and yes that could cause your idle miss also, look at the brake booster hose, intake manifold gaskets/seal needing replacing or the intake bolts not torqued right, etc. Also check the intake plenum on your engine, they get a leak, its between the throttle body and the intake, its rubber, and it gets a hole on the bottom, that hole will allow unmetered air into the intake causing a lean mixture. I am SHOCKED you passed the emissions inspection, but good for you...

[hms200]

The guru used to say that high speed overheating could be caused by a slipping water pump belt, definately check the belt. Look for a shine on the belt, from slipping. Check the pulley for roughness or locking, and check the tension arm to see if its binding AT ALL.

Good you checked the lower hose, and the spring is intact

One thing you said concerns me, "appears to be running like a champ, other than slight idle stumble at times, more noticable when cold than one hot"

This cold 'miss' is what I got when my head gasket was bad in the beginning.... not a good sign. Again, go for a test, now that the coolant has been in for awhile. If your head gasket is beginning to go bad, it could be the beginning, I drove mine for a year, watching the temp needle, but it ran 217 instead of 205 during that year.

The P0171 and P0174 is a lean mixture on both banks, and yes that could cause your idle miss also, look at the brake booster hose, intake manifold gaskets/seal needing replacing or the intake bolts not torqued right, etc. Also check the intake plenum on your engine, they get a leak, its between the throttle body and the intake, its rubber, and it gets a hole on the bottom, that hole will allow unmetered air into the intake causing a lean mixture. I am SHOCKED you passed the emissions inspection, but good for you...

Sorry, to clarify on the idle, I didn't describe properly. There is no miss, so "stumble" was the wrong word for me to have used. Rather, at times (not a consistant issue) when cold it wouldn't stay at a steady idle speed, rising about 50-100 rpm's, then back down to normal...then up for a bit then norm, etc...not rapid up/down cycle...ocassional. It has always run very smooth and responsive since I've had it.

Brake booster hose was another that I had found loose, with no hose clamps on either end, but I resolved that earlier. I had mentioned way back after doing compression testing about the shoddy/sloppy engine top end reassembly by dealer evidently, when they had rebuilt the block I can only assume. I had said back then that I wondered what else I might find that had been just thrown back together. That's also when I found the cracked/split rubber L connector for crankcase vent line coming off the throttle body that somebody had attempted half !@# to mend, with electrical tape of all things. The intake plenum (if you mean the short rubber boot between throttle body and intake manifold?) I checked the other day for being secure (clamp) but I didn't check for a crack in the rubber...good tip, I'll check. I also did check the plenum between throttle body and air filter for cracks and clamped secure. Didn't find any other obvious sources for potential vacuum leaks or unmetered air leaks, and I've looked it over pretty close multiple times since seeing those codes. I also inspected and wiped clean both the MAP sensor and IAC valve...nothing visually abnormal spotted with either.

Honestly I was shocked as well on passing emissions. The numbers were actually excellent...nowhere near the max limit for any of them. If the SES had popped back on during testing then that would have failed me as well here in Colorado. The codes returned and triggered the SES light again about 5 miles down the road from emissions testing, on my way home. You ever used propane gas (with no flame obviously ) to try and isolate a vacuum leak? I have never tried, but it's said that when the propane gas is sucked in it can react to engine idle, depending on how quickly the computer is able to trigger a compensation, so you then know you're at/near a leak.

Why did you ask about status of the new radiator earlier? Just verifying if it had been changed out or not...was not going somewhere with an idea on that?

HMS

[BodybyFisher]

don't go nuts with the vacuum leak, I am about 90% sure its the bottom of the plenum, not the clamps, the plenum yourself its a common failure. EGR gunk settles there and deteriorates the rubber. You will find a leak

Glad you clarified the miss or stumble, that is not what I had, I had a MISS for 5 minutes, I believe coolant leaked into the cylinder and caused the miss till the coolant was gone

That ranging idle is probably the result of the lean mixture, fixing the problem will probably eliminate that

Fix that, and keep driving it, it certainly sounds like the beginnings of a head gasket problem, but the symptoms are not clear at this point. The temp spikes you are getting are ominous. Once you have driven the car a bunch, smell the tank for exhaust fumes and test the coolant, it may take time for the by products to show in the beginning of the problem. I am not being negative on this problem I am hoping for the best, but he dealer said HG (not sure how, unless they assumed it) or used an electronic sniffer, you are having some odd symptoms and we have done a lot of diagnosis. Keep looking at the things we have been discussion here

The spikes you are getting are hard to explain

[hms200]

don't go nuts with the vacuum leak, I am about 90% sure its the bottom of the plenum, not the clamps, the plenum yourself its a common failure. EGR gunk settles there and deteriorates the rubber. You will find a leak

Glad you clarified the miss or stumble, that is not what I had, I had a MISS for 5 minutes, I believe coolant leaked into the cylinder and caused the miss till the coolant was gone

That ranging idle is probably the result of the lean mixture, fixing the problem will probably eliminate that

Fix that, and keep driving it, it certainly sounds like the beginnings of a head gasket problem, but the symptoms are not clear at this point. The temp spikes you are getting are ominous. Once you have driven the car a bunch, smell the tank for exhaust fumes and test the coolant, it may take time for the by products to show in the beginning of the problem. I am not being negative on this problem I am hoping for the best, but he dealer said HG (not sure how, unless they assumed it) or used an electronic sniffer, you are having some odd symptoms and we have done a lot of diagnosis. Keep looking at the things we have been discussion here

The spikes you are getting are hard to explain

Thank you sir...will do on all points. I'll be sure to check plenum also. Hate to say it, but regardless of HGs I'll soon be replaceing the intake manifold gasket anyway. Why?? Um...one of the intake manifold bolts twisted off on me the other night as I tested torque on the manifold. I did NOT over torque it...appears it was already fractured because it turned semi-easy and then snapped, long before I'd reached any real tension. I know...that spot can now be a source for air leak. Nothing has changed yet with any symptoms and all other bolts were and are tight...so maybe it will not leak. In any case, at some point I'll have to remove the manifold and extract/replace that broken bolt. Hey, it'll give me a justified opportunity for a little deeper overall inspection.

If idle issue isn't a vacuum leak or cracked plenum then any venture as to next place to search? I sure don't desire to start shotgun replacement of the expensive sensors...some are very pricey. I already know to NOT replace the o2 sensors...they are good...that much I do understand, and why.

HMS

[BodybyFisher]

If idle issue isn't a vacuum leak or cracked plenum then any venture as to next place to search? I sure don't desire to start shotgun replacement of the expensive sensors...some are very pricey. I already know to NOT replace the o2 sensors...they are good...that much I do understand, and why

No need to speculate until those codes are gone, that is the first stop, 90% sure

The second stop is to extract that bolt, a vacuum leak like that could cycle the idle, but most likely cause a misfire (P0300)

[hms200]

My responses below ...thx much!

During highway speeds I observed TWO momentary temp rises to a point between 225 and 245 degree ticks, but then quickly returned back to its normal. Huh??

When did that occur?, after the new tank? It is possible that if this occurred after putting in the tank, the system needed to stabilize.

[HMS REPLY: It happened during highway drive test after replacing tank, about 8 miles into the voyage, and 2nd time about 2-3 miles later...going between 70-75 mph I believe. I then turned around and headed back out of fear that it was about to seriously overheat on me. I altered my speed on return to between 65-70 mph...needle never moved again on me though.]

As others have said, DO NOT replace the water pump, it is basically indistructible, NO WAY the impellers corroded away, they are misinformed on this water pump.

[HMS REPLY: Thx for the validation on bugus info. No plans to change pump...already rejected that diagnosis as well, as did the shop in Parker also that I spoke with today. He was attempting to shotgun the issue at my expense...far too typical these days with shops, with far too many uninformed, helpless victims to that I'm sure...grrr.]

Check again to make sure that the water pump belt tensioner is free and NOT binding at all. Overheating at highway speeds can be caused by the water pump belt slipping

[HMS REPLY: I will check again. No signs of belt being in distress though. Perhaps at this point I should physically pop off the belt for closer inspection?]

At highway speeds ram air is blowing through the radiator so any problems with the cooling fans is out of the question

What is the status of your radiator?, don't you have one sitting there waiting to go in?

[HMS REPLY: Yep, I have the new radiator still sitting to the side, boxed up with receipt so I can return it if determined to not be needed. Whay do you ask...suspecting possible radiator blockage perhaps? The multiple draining and fill-ups I've done on coolant all flowed really well, out and in...no slow gurgling or any such if that may add any light?]

I would think that if you were getting engine coolant temp sensor problems you would set a code

These are the codes you can get from the engine coolant temp sensor

P0115 - Engine Coolant Temperature (ECT) Sensor Circuit

P0116 - Engine Coolant Temperature (ECT) Sensor Performance

P0117 - Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

P0118 - Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

P0119 - Engine Coolant Temperature Circuit Intermittent

So other than the spikes, does it appear to be burning up?

[HMS REPLY: Zero such codes have appeared, either current or history...nada. Nope, it doesn't at all seem to be burning up...appears to be running like a champ, other than slight idle stumble at times, more noticable when cold than one hot. I suspect that may be associated with whatever is throwing the two codes I reported before, P0171 & P0174 in current that did reappear later after I cleared them...thankfully AFTER the emissions test rather than DURING. ]

Could the lower hose be collapsing from suction? Try squeezing it to see if its soft

[HMS REPLY: The lower hose isn't soft...feels fine. I can also feel the inner wire spring...intact all the way from radiator to thermostat housing. Saw the end of it also when I replaced the thermostat and it looked in excellent condition...no rust or crud was present on that end.]

HMS

Well...I failed the highway test as defined here...so it would appear I can take this as my final validation. Anybody disagree or have any reservations? Appears it is in fact the HG's. Road test performed as defined (see link) took temp up to and slightly beyond 145 degrees, though recovering quickly as driving intensity eased up. What blows my mind is how fast the temp recovers. I've never seen that before...strange. Here's the highway test conducted...guess my prior tests were just too easy and too steady. I was rather aggressive on this last failed test.

http://www.northstarperformance.com/hgfaq.php

HMS

[Texas Jim]

Well...I failed the highway test as defined here...so it would appear I can take this as my final validation. Anybody disagree or have any reservations? Appears it is in fact the HG's. Road test performed as defined (see link) took temp up to and slightly beyond 145 degrees, though recovering quickly as driving intensity eased up. What blows my mind is how fast the temp recovers. I've never seen that before...strange. Here's the highway test conducted...guess my prior tests were just too easy and too steady. I was rather aggressive on this last failed test.

http://www.northstar...e.com/hgfaq.php

HMS

Please elaborate...

What exactly did you do and what exactly happened?

[BodybyFisher]

My responses below ...thx much!

During highway speeds I observed TWO momentary temp rises to a point between 225 and 245 degree ticks, but then quickly returned back to its normal. Huh??

When did that occur?, after the new tank? It is possible that if this occurred after putting in the tank, the system needed to stabilize.

[HMS REPLY: It happened during highway drive test after replacing tank, about 8 miles into the voyage, and 2nd time about 2-3 miles later...going between 70-75 mph I believe. I then turned around and headed back out of fear that it was about to seriously overheat on me. I altered my speed on return to between 65-70 mph...needle never moved again on me though.]

As others have said, DO NOT replace the water pump, it is basically indistructible, NO WAY the impellers corroded away, they are misinformed on this water pump.

[HMS REPLY: Thx for the validation on bugus info. No plans to change pump...already rejected that diagnosis as well, as did the shop in Parker also that I spoke with today. He was attempting to shotgun the issue at my expense...far too typical these days with shops, with far too many uninformed, helpless victims to that I'm sure...grrr.]

Check again to make sure that the water pump belt tensioner is free and NOT binding at all. Overheating at highway speeds can be caused by the water pump belt slipping

[HMS REPLY: I will check again. No signs of belt being in distress though. Perhaps at this point I should physically pop off the belt for closer inspection?]

At highway speeds ram air is blowing through the radiator so any problems with the cooling fans is out of the question

What is the status of your radiator?, don't you have one sitting there waiting to go in?

[HMS REPLY: Yep, I have the new radiator still sitting to the side, boxed up with receipt so I can return it if determined to not be needed. Whay do you ask...suspecting possible radiator blockage perhaps? The multiple draining and fill-ups I've done on coolant all flowed really well, out and in...no slow gurgling or any such if that may add any light?]

I would think that if you were getting engine coolant temp sensor problems you would set a code

These are the codes you can get from the engine coolant temp sensor

P0115 - Engine Coolant Temperature (ECT) Sensor Circuit

P0116 - Engine Coolant Temperature (ECT) Sensor Performance

P0117 - Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

P0118 - Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

P0119 - Engine Coolant Temperature Circuit Intermittent

So other than the spikes, does it appear to be burning up?

[HMS REPLY: Zero such codes have appeared, either current or history...nada. Nope, it doesn't at all seem to be burning up...appears to be running like a champ, other than slight idle stumble at times, more noticable when cold than one hot. I suspect that may be associated with whatever is throwing the two codes I reported before, P0171 & P0174 in current that did reappear later after I cleared them...thankfully AFTER the emissions test rather than DURING. ]

Could the lower hose be collapsing from suction? Try squeezing it to see if its soft

[HMS REPLY: The lower hose isn't soft...feels fine. I can also feel the inner wire spring...intact all the way from radiator to thermostat housing. Saw the end of it also when I replaced the thermostat and it looked in excellent condition...no rust or crud was present on that end.]

HMS

Well...I failed the highway test as defined here...so it would appear I can take this as my final validation. Anybody disagree or have any reservations? Appears it is in fact the HG's. Road test performed as defined (see link) took temp up to and slightly beyond 145 degrees, though recovering quickly as driving intensity eased up. What blows my mind is how fast the temp recovers. I've never seen that before...strange. Here's the highway test conducted...guess my prior tests were just too easy and too steady. I was rather aggressive on this last failed test.

http://www.northstar...e.com/hgfaq.php

HMS

As Jim implied your post here is vague. Always give details. Did you mean 245 degrees or 145 degrees?

That is a standard test, drive it hard, find long inclines, labor the engine and if the head gasket is bad, it will overheat. You drove it hard and it overheated? You are at the beginning of the head gasket problem, the bolt threads are probably shot and the stress on the engine, probably pushes up the head to the point where combustion gases enter the coolant passages heating the coolant up.

Ill bet now you will find that if you tested your coolant, your tester would change colors and you may even smell coolant in the tank

[hms200]

My responses below ...thx much!

During highway speeds I observed TWO momentary temp rises to a point between 225 and 245 degree ticks, but then quickly returned back to its normal. Huh??

When did that occur?, after the new tank? It is possible that if this occurred after putting in the tank, the system needed to stabilize.

[HMS REPLY: It happened during highway drive test after replacing tank, about 8 miles into the voyage, and 2nd time about 2-3 miles later...going between 70-75 mph I believe. I then turned around and headed back out of fear that it was about to seriously overheat on me. I altered my speed on return to between 65-70 mph...needle never moved again on me though.]

As others have said, DO NOT replace the water pump, it is basically indistructible, NO WAY the impellers corroded away, they are misinformed on this water pump.

[HMS REPLY: Thx for the validation on bugus info. No plans to change pump...already rejected that diagnosis as well, as did the shop in Parker also that I spoke with today. He was attempting to shotgun the issue at my expense...far too typical these days with shops, with far too many uninformed, helpless victims to that I'm sure...grrr.]

Check again to make sure that the water pump belt tensioner is free and NOT binding at all. Overheating at highway speeds can be caused by the water pump belt slipping

[HMS REPLY: I will check again. No signs of belt being in distress though. Perhaps at this point I should physically pop off the belt for closer inspection?]

At highway speeds ram air is blowing through the radiator so any problems with the cooling fans is out of the question

What is the status of your radiator?, don't you have one sitting there waiting to go in?

[HMS REPLY: Yep, I have the new radiator still sitting to the side, boxed up with receipt so I can return it if determined to not be needed. Whay do you ask...suspecting possible radiator blockage perhaps? The multiple draining and fill-ups I've done on coolant all flowed really well, out and in...no slow gurgling or any such if that may add any light?]

I would think that if you were getting engine coolant temp sensor problems you would set a code

These are the codes you can get from the engine coolant temp sensor

P0115 - Engine Coolant Temperature (ECT) Sensor Circuit

P0116 - Engine Coolant Temperature (ECT) Sensor Performance

P0117 - Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

P0118 - Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

P0119 - Engine Coolant Temperature Circuit Intermittent

So other than the spikes, does it appear to be burning up?

[HMS REPLY: Zero such codes have appeared, either current or history...nada. Nope, it doesn't at all seem to be burning up...appears to be running like a champ, other than slight idle stumble at times, more noticable when cold than one hot. I suspect that may be associated with whatever is throwing the two codes I reported before, P0171 & P0174 in current that did reappear later after I cleared them...thankfully AFTER the emissions test rather than DURING. ]

Could the lower hose be collapsing from suction? Try squeezing it to see if its soft

[HMS REPLY: The lower hose isn't soft...feels fine. I can also feel the inner wire spring...intact all the way from radiator to thermostat housing. Saw the end of it also when I replaced the thermostat and it looked in excellent condition...no rust or crud was present on that end.]

HMS

Well...I failed the highway test as defined here...so it would appear I can take this as my final validation. Anybody disagree or have any reservations? Appears it is in fact the HG's. Road test performed as defined (see link) took temp up to and slightly beyond 145 degrees, though recovering quickly as driving intensity eased up. What blows my mind is how fast the temp recovers. I've never seen that before...strange. Here's the highway test conducted...guess my prior tests were just too easy and too steady. I was rather aggressive on this last failed test.

http://www.northstar...e.com/hgfaq.php

HMS

As Jim implied your post here is vague. Always give details. Did you mean 245 degrees or 145 degrees?

That is a standard test, drive it hard, find long inclines, labor the engine and if the head gasket is bad, it will overheat. You drove it hard and it overheated? You are at the beginning of the head gasket problem, the bolt threads are probably shot and the stress on the engine, probably pushes up the head to the point where combustion gases enter the coolant passages heating the coolant up.

Ill bet now you will find that if you tested your coolant, your tester would change colors and you may even smell coolant in the tank

Sorry guys for lack of detail in my last post, and yes, I meant 245+ (oops on that typo) and YEP on all other points of speculation you just made BBF. All my prior highway road tests were fast and sustained, but were not really hard and aggressive. This time I buried my foot in the peddle, let off (not to 30 mph, but I slowed) and then buried it again...over and over. The inclines were best indicators as you said BBF...accelerated hard all the way up and that needle then would really start to move on me. I never took it far beyond 245 degree mark but I could SURE get it to that point and beyond easily enough, at will. I'm still surprised by how easily I can control the temp to either direction...that just seems so bazaar. When I ease off, the engine temp recovered immediately and completely. Never did I experience any bad engine performance as well (it always seemed happy), though never took it past slightly beyond 245.

Upon return to garage the car was back to normal temp, which as I said, it took little time for it to recover back to norm. Popping the hood, that engine simply was NOT red hot, not cooking...it was normal operation temp. Tank was warm to the touch...far from red hot...and same for the cap, though there was some minor residual smell of prior coolant steam when I popped the hood...minor, not extreme. There was no boiling activity/noise from within the tank...and no steam pouring from the cap or overflow tube. After cooling for a bit (maybe an hour) I released final pressure (small amount of remaining air pressure only, no major coolant discharge, other than maybe a few drips (new cap I had installed is the pressure release lever type). Sniffed the tank...yep, sure smelled of exhaust to me. I verified coolant level in tank (3-4 inches from top, not dry but seemed a bit low...did NOT add any coolant), reapplied the block tester to tank and it went from blue to green in short order once the bubbles started appearing...then to yellow...then water surged from tank and up into the tester as well...test over...popped the cap back on to stop the surge overflow onto my garage floor. I don't believe the coolant surge threw off test results. I believe it was a surge of exhaust gasses just before coolant surged from tank, like a burp if that makes any sense. Yes, once water hits the tester then all bets are off. When it turned yellow I quickly pulled tester from tank mouth to inspect and there was no water at the top yet...but it did come flowing up quickly from that point. Btw...after popping cap back on I went quickly to turn off engine...temp gauge sitting at high side of normal (~210 mark). I'll do the test again today with even less coolant in the tank this time because I didn't refill it after the surge event. Green isn't suppose to be an indicator of exhaust unless its diesel as I understand it. But it did turn yellow when bubbles started surging extra strong just before it overflowed. The tank smell was sweet and pungent, not that of just coolant.

So to me, all the outward signs and conclusion I'm sitting with at this stage appear to be a minor sustained head gasket leak under normal operation and major leakage under extreme load. That seems to be similar pattern described by others as well, which makes this such a tricky thing to diagnose, contrary to most vehicle blown gaskets where it's a true blow out rather than head bolt induced. Make sense? I may have forced a more extreme leakage with the intense road test, whereby I was then able to get more definitive outward signs this time. As for the plugs being perfectly clean in earlier inspection, not sure if it's possible, but maybe there is simply a one way leak happening...exhaust into coolant but no coolant into cylinders. Is that even possible you think? I'd say anything is possible from this point with the Northstar based on bazaar test results I've come up with to this point. Btw...I inspected pump belt again and still see out outward evidence of slippage...no abuse to the belt observed and not shiny. Also, no coolant leakage or smell anywhere else within engine compartment other than at the tank area.

HMS

[BodybyFisher]

Now you are starting to get bad HG indicators with the high temp spikes with hard acceleration

keep in mind that each head has 10 bolts, if one or two pull out, the surrounding bolts take up the combustion load that pushs up on the head. When you drive the engine hard, the head is unable to be held down securely where the bolts are pulled, so combustion gases excape into the coolant passage.

I recently posted something that showed that if a bad bolt hole is found, fix the surrounding bolt holes also as they have been taking up the load

The most definitive test at this point would be a sniffer, to 100% confirm that you have combustion by products entering the cooling system

What to you intend to do once you confirm a HG problem?

[hms200]

Now you are starting to get bad HG indicators with the high temp spikes with hard acceleration

keep in mind that each head has 10 bolts, if one or two pull out, the surrounding bolts take up the combustion load that pushs up on the head. When you drive the engine hard, the head is unable to be held down securely where the bolts are pulled, so combustion gases excape into the coolant passage.

I recently posted something that showed that if a bad bolt hole is found, fix the surrounding bolt holes also as they have been taking up the load

The most definitive test at this point would be a sniffer, to 100% confirm that you have combustion by products entering the cooling system

What to you intend to do once you confirm a HG problem?

Yep...I've seen the posts about cylinder on either side of a failed bolt, and I do understand the reasoning about stress/pressure transfer to the others...makes total sense. I agree with the sniffer test as hopefully my final proof...would be foolish to have taken things to such extreme testing effort and not go this final step.

If proven HGs then where do I go from there? Tear her down in-car and apply "Norm's Solution" to all 20 head bolts I suppose. I can't pull the engine (no lift for cradle drop and no crane for a top pull...and no space for either anyway), so unless I farmed out the job, then "Jake's Studs" are ruled out due to lack of proper required clearance for rear bank. My questions and concerns are with very tight access clearance at rear of engine for exhaust manifold removal so I would have a host of questions, but tilting engine forward may be the resolve to that. Also MAJOR questions would appear on cam timing BEFORE I tear it down...to understand exactly how best to disassemble for correct reassembly. I don't have the Northstar Cam Timing Kit I've seen, if required...but not so expensive if I must obtain.

Is that what you were asking BBF? Thoughts or concerns with my plan of attack if HGs?

HMS

[Ranger]

What blows my mind is how fast the temp recovers. I've never seen that before..

When the HG fails it puts very hot exhaust gases in the cooling system. They form an air pocket that reaches the ECT sensor which causes the gauge to rise. Eventually the coolant sloshes through the water jacket and hits the ECT sensor and the gauge quickly returns to normal.

As BBF said, you are in the early stages and have probably only one bolt failed. As time goes on, coolant will make it's way to the next bolt and seep into the threads. Eventually that will cause a galvanic action and corrode the threads til they fail and then move on to the next bolt with the symptoms getting progressively worse with each one. That's why the Northstar can be nursed along for such a long time. It is not the HG that was breached and failed, but the bolt threads that slowly let loose.

As for any questions, I think both Zonie and Tateos have a tutorial in the Tech Tips forum at CF, that MAY address some of your questions.

[hms200]

Thx Ranger...I'll search.

HMS

[hms200]

Thx Ranger...I'll search.

HMS

Zonie provided a great prior discussion thread and a few pics with lots of tips. But it was all focused on cradle drop and car lift in a manner where maybe I could perform in my garage with jacks, jack stands, blocks and an engine lift for raising the car. But I'm still sticking to in-car effort at this stage until/unless I see solid evidence that it's a really bad idea.

Btw...as mentioned last night, I performed ANOTHER block test using my blue water.

1. Pulled cap and inspected coolant level in tank - appears about half full.

2. Cranked engine in the garage and let it reach close to normal temp at an idle only.

3. Notification at crank up given at message center to check coolant level.

4. Inserted tester with fresh blue chemicals and pumped it down a few times.

5. As engine warmed to normal gauge position it began bubbling into tester on its own - plus I pumped it a few times as well.

6. Water turned green BUT never turned yellow.

7. Continued test for about 10 minutes but never got yellow, no overheat at idle and no boil over.

8. Discontinued test - grrrr...

0. Sniffed tank...definitely smells like exhaust is present, as it did last night.

10. WILL FIND A SHOP TO PERFORM A FINAL COOLANT SNIFFER TEST...PERIOD!! - This is nonsense and wasting time of all you great guys that have hung in with me on this insanity! Sheesh...old school does NOT apply to anything associated with Northstar HG issue!! I may be very stubborn...but not stupid forever. LOL

HMS

[BodybyFisher]

It has been said that you need to relearn everything when it comes to the Northstar, that was the case with my experience, so dont feel frustrated.

That exhaust smell in the tank is what we have been waiting for

I would not recommend you leaving the engine in place, and would rather you pull the engine out of the top, KEVIN/KHE did that

Good luck, let us know how we can help

[hms200]

It has been said that you need to relearn everything when it comes to the Northstar, that was the case with my experience, so dont feel frustrated.

That exhaust smell in the tank is what we have been waiting for

I would not recommend you leaving the engine in place, and would rather you pull the engine out of the top, KEVIN/KHE did that

Good luck, let us know how we can help

Thank you BBF...you'll hear more from me I'm certain.

Oh...what is everybody doing with the heads themselves when pulled for HGs and HB repair? I've heard nothing on that...machine shop inspection for cracks/warped, resurfacing, pressure test, valve job and seals if needed? I think that's a given...but may as well ask since nothing else so far seems to hold true with old school measures.

HMS

[KHE]

But I'm still sticking to in-car effort at this stage until/unless I see solid evidence that it's a really bad idea.

Not a good idea - there are so many fasteners at awkward angles. The brace that goes from the top of the rear head (passenger side)to the transmission between the rear exhaust manifold is a royal SOB. Also drilling, machining the block with it in the car will be more difficult vs. having it on an engine stand. Also, reading the torque angle meter will be much more difficult with the engine in the car. The heads are heavy and getting them in place will also be a lot harder with the engine in the car.

Oh...what is everybody doing with the heads themselves when pulled for HGs and HB repair? I've heard nothing on that...machine shop inspection for cracks/warped, resurfacing, pressure test, valve job and seals if needed? I think that's a given...but may as well ask since nothing else so far seems to hold true with old school measures.

HMS

No need for valve seal replacement - the originals are viton and will last several lifetimes. Also, the block and heads rarely are "warped" on these engines.

[BodybyFisher]

To add to what Kevin said, IF you stud the block, there is no way you can leave the engine in place