275 degrees "oh no"

[blk987]

The 98 deville with the northsar has been diagnosed with a blown head/gasket by Pep Boys. Can anyone answer a few questions for me that would extremely help ease my pain. A short history; New radiator last month new thermostat(not oem), flush and fill, radiator pellets (bars leak), and it wouldnt stop overheating and the surge tank expelling all coolant onto the ground so then I took it for a diagnosis. Question 1,Ive seen many times on this site the northstar is not common for head gasket problems is this true? ques.2 is compression test the only way to determine head problems and how accurate is it? ques. 3 Im knowledgeble about cars and mechanically inclined and have done many repairs on many cars but is head gaskets/heads, something you can do out of your garage? Also if I do repair the head gaskets am I still going to be looking for a problem with the cooling system and why they blew in the first place?

Im not ready to give this car up yet its tooo darn beautiful not a scratch or a dent on her. Im planning to try the heads myself any comments, helpful hints, links or questions that you all have would be greatly appreciated throughout my process. You all helped out a lot with other issues which has got the caddy in top shape but back to square one again. Im going to start today probably and I will post pics and my progress.

[BodybyFisher]

How did Pep Boys conclude to it being the head gasket? What tests did they do?

Is the proper 50/50 mix of coolant being used even though its boiling over or did you use water?

Has the cap been replaced?

Have you checked the purge line to see if its clogged?

While the engine is cool, open the coolant tank and SMELL the coolant, do you smell exhaust fumes?

Does the engine run rough for about 5 minutes in the morning and then level out?

Has the cooling system been pressure tested?

It IS VERY possible to MIS-diagnose this problem, I recently saved someone from doing a $4000 head gasket, and we have fixed many an overheating problem here

[blk987]

I asked how they did the test and they only answered by saying a compression test and he would not elaborate. I measured the coolant and water exactly 50/50 I even used measuring cups just to rule that out. I did replace the surge tank cap. The engine does run a little (very little) sluggish in the morning but thats gone by the time I put it in reverse to come out of the drive. To my knowledge the coolant system has not been pressure tested. Im going to check the purge line for clogs and surge tank for exhaust fumes immediately

[Cadillac Jim]

Head gasket problems occur on about 15% of older Northstars, according to a poll on this site. This may be high since Caddyinfo forums is a well-known and busy go-to place for solving problems with Cadillacs of all ages. One thing you can do to virtually assure that your Northstar will have head gasket leakage in about two years is to let your coolant go over its five year limit as stated in the owner's manual, the FSM, and the bottles in which DexCool is sold; most often seven-year-old Northstars that have never had the coolant changed report head gasket problems. Going by the age, your car probably had its coolant changed in 2005 but not since, and that has been seven years. If the coolant is kept fresh and the car is otherwise well-maintained and not abused, head gasket problems are rare.

Head gasket leakage causes overheating. The mechanism as I understand it is that squirting of combustion gases into the coolant generates steam bubbles that collect at the thermostat, which stays closed until the bubble passes. The first symptoms are loss of coolant without dripping or visible leaks, then occasional temperature spikes after climbing a hill or passing a truck at highway speeds. These are sudden jumps in the temperature gauge followed by an almost equally speedy decline back to normal temperatures (about straight up on the temperature gauge). These occur about a minute after you drop back to normal speed and at first they may go unnoticed. The problem gradually increases in severity until overheating and coolant loss make the care un-drivable, a process that takes several months.

Part of the process of head gasket repair (or any repair that involves removing the cylinder heads) is adding brass inserts for the had bolt holes; the GM recommended procedure is to use Timeserts (see Timesert.com; they sell factory-approved inserts for aluminum engines from GM, Ford, Porsche, etc.).

Overheating of Northstars is just about unheard of when the cooling system and engine are in good shape. The cooling system is designed to allow driving at top speed on the Autobahn for long periods of time without problems. Selected engines are removed from production and run at full throttle and top RPM for 300 hours for durability testing, a feat not many production engines can withstand but is expected performance for Northstars. The same basic design was used as the Indianapolis 500 engine for a couple of years, is the basis for 500+ hp supercharged versions in the V-series STS and XLR, and is used by chrfab.com in building sand car and racing engines.

Once properly repaired and properly maintained, your car will not overheat. The keys are good fans and fan relays, a good radiator that is not clogged (done!), a good AC/Delco thermostat of the proper temperature (180 F) and properly installed, a good water pump, water pump belt and tensioner, a good AC/Delco radiator cap, 50-50 Dexcool and distilled water ($0.50 a gallon at WalMart), and no leaks at the hose clamps or water pump seal, or crossover gaskets. Anyone who does a head gasket repair on an older car should repair or renew all these items as appropriate.

[BodybyFisher]

Do you know where and how to check the purge line? The function of the purge line is to allow air out of the cooling system from the TOP of the system. If its clogged, air will be in the system and cause overheating as the water pump will cavitate

With the engine cool, at the top of the coolant tank there is a hose, NOT the over flow hose off the cap, the other one. Engine cool, engine off, pull the hose off gently so as not to break the nipple off the tank, and let it hang, start engine and let IDLE, go look at hose, it should be flowing coolant steadily.

Report the results of that test on your purge line. If the purge line does NOT flow coolant the "bolt with a hole in it", must be removed and cleared, DO NOT blow air through the purge line, CLEAR the bolt with a hole in it.

Here is the location of the bolt with a hole in it, see the circled hose to the right of the upper radiator hose, remove the hose, use a 15 mm wrench to take the bolt out and see if the orifice is clogged and clear it

[blk987]

How did Pep Boys conclude to it being the head gasket? What tests did they do?

Is the proper 50/50 mix of coolant being used even though its boiling over or did you use water?

Has the cap been replaced?

Have you checked the purge line to see if its clogged?

While the engine is cool, open the coolant tank and SMELL the coolant, do you smell exhaust fumes?

Does the engine run rough for about 5 minutes in the morning and then level out?

Has the cooling system been pressure tested?

It IS VERY possible to MIS-diagnose this problem, I recently saved someone from doing a $4000 head gasket, and we have fixed many an overheating problem here

The surge tank kinda smells like paint, I dont smell heavy exhaust fumes its more like burnt coolant. Also if Im correct the purge line runs from the crossover over the top of the motor to the surge reservoir and I took the rubber hoses completely off and I could blow through them, I did not blow into the motor the hoses were completely disconected

.

[BodybyFisher]

Yes that is the purge line, it crosses the top if the engine and connects to the TB pre-heat circuit to stop icing

The worst thing to do is to BLOW through it, you would dislodge the clog.

When you drive the car for a few miles let it cool and test the purge line the way I described above

[blk987]

Do you know where and how to check the purge line? The function of the purge line is to allow air out of the cooling system from the TOP of the system. If its clogged, air will be in the system and cause overheating as the water pump will cavitate

With the engine cool, at the top of the coolant tank there is a hose, NOT the over flow hose off the cap, the other one. Engine cool, engine off, pull the hose off gently so as not to break the nipple off the tank, and let it hang, start engine and let IDLE, go look at hose, it should be flowing coolant steadily.

Report the results of that test on your purge line. If the purge line does NOT flow coolant the "bolt with a hole in it", must be removed and cleared, DO NOT blow air through the purge line, CLEAR the bolt with a hole in it.

Here is the location of the bolt with a hole in it, see the circled hose to the right of the upper radiator hose, remove the hose, use a 15 mm wrench to take the bolt out and see if the orifice is clogged and clear it

I took the purge line off the surge reservoir and let the engine idle and it did flow out of the purge line somewhat steadily.

[BodybyFisher]

Ok, then, you can buy a test kit to test for combustion by products in your coolant OR, you can go to a good radiator shop and have them test the coolant for combustion by products.

NAPA sells a kit that you can buy to test your coolant, as a final conclusion you should test your coolant

However, it does not sound good so far, the smell in the tank and brief misfire are symptoms of a leaking head gasket

This is not really a DIY job unless you are an advanced mechanic, the carriage needs to be dropped and the block needs to be timeserted, bolts replaced, etc.

It does not sound good, new cap, new radiator, 50/50 coolant concentration, purge line flowing,

How are your cooling fans working?

[blk987]

Ok, then, you can buy a test kit to test for combustion by products in your coolant OR, you can go to a good radiator shop and have them test the coolant for combustion by products.

NAPA sells a kit that you can buy to test your coolant, as a final conclusion you should test your coolant

However, it does not sound good so far, the smell in the tank and brief misfire are symptoms of a leaking head gasket

This is not really a DIY job unless you are an advanced mechanic, the carriage needs to be dropped and the block needs to be timeserted, bolts replaced, etc.

It does not sound good, new cap, new radiator, 50/50 coolant concentration, purge line flowing,

How are your cooling fans working?

Cooling fans are working properly.

[Ranger]

Question 1,Ive seen many times on this site the northstar is not common for head gasket problems is this true?

They are somewhat common. Especially '97 - '99 with the '99's leading the pack.

ques.2 is compression test the only way to determine head problems and how accurate is it?

No, as mentioned a block test kit will diagnose it, but a compression test will tell you nothing about a head gasket. A leak down test is what is needed.

3 Im knowledgeble about cars and mechanically inclined and have done many repairs on many cars but is head gaskets/heads, something you can do out of your garage?

As BBF mentioned it is not your average HG job. You have to drop the entire drivetrain out the bottom and insert or stud the block. If you use inserts consider Norm's inserts available on Ebay. They have a coarser thread than Timeserts. If you go with studs contact Jake at http://www.northstarperformance.com, but be patient. He is in the process of moving his operation from Ontario to Manitoba.

Part of the process of head gasket repair (or any repair that involves removing the cylinder heads) is adding brass inserts for the had bolt holes

I think you meant steel vs brass Jim.

[Cadillac Jim]

Ranger - thanks for the correction. I did not have direct knowledge of Timeserts.

Once a Northstar head gasket problem is bad enough to cause overheating, it can be detected by a cooling system pressure test, which demands that the radiator, water pump, hoses and clamps all be in good condition with no leaks. Another sure way is to note a smell of coolant in the exhaust right after you start it in the morning. A more scientific way is to test the coolant for combustion products, which can be done by a good radiator shop or other mechanic.

[blk987]

Thank you for the responses so far!! Im going to perform a couple tests myself like you all stated and hopefully have a definite diagnosis by monday evening.

[blk987]

Question 1,Ive seen many times on this site the northstar is not common for head gasket problems is this true?

They are somewhat common. Especially '97 - '99 with the '99's leading the pack.

ques.2 is compression test the only way to determine head problems and how accurate is it?

No, as mentioned a block test kit will diagnose it, but a compression test will tell you nothing about a head gasket. A leak down test is what is needed.

3 Im knowledgeble about cars and mechanically inclined and have done many repairs on many cars but is head gaskets/heads, something you can do out of your garage?

As BBF mentioned it is not your average HG job. You have to drop the entire drivetrain out the bottom and insert or stud the block. If you use inserts consider Norm's inserts available on Ebay. They have a coarser thread than Timeserts. If you go with studs contact Jake at http://www.northstarperformance.com, but be patient. He is in the process of moving his operation from Ontario to Manitoba.

Part of the process of head gasket repair (or any repair that involves removing the cylinder heads) is adding brass inserts for the had bolt holes

I think you meant steel vs brass Jim.

Hey there its been a while and maybe I should have started a new thread but I wasnt sure. The car is still sitting I have been too busy. Although i did get around to doing the leak down test like you said and the results came out fine. All cylinders tested good. I followed the instructions perfectly I put each cylinder at TDC, the motor was warmed up before testing and it just doesnt make sense to me. I did have another member tell me that if the head bolts are pulled enough that it will give a false reading which does make sense but before I dive into the heads I was looking for any suggestions to determining faulty gaskets(other than going to an engine shop). I do not have a couple of the definite signs like white smoke or bubbles in the coolant reservoir the only signs are overheating and a major loss of coolant externally so Im kinda at a loss on what to do next. If anyone could please help Im ready to get back behind the wheel of her.

[Cadillac Jim]

The leakdown test is good for iron engines but not definitive on an all-aluminum engine. The head can seal when the engine is cold or running but not pulling a lot of torque until the leak gets pretty bad, after which the car will show lots of other obvious signs like constant overheating on the highway. The definitive test for Northstars is testing the coolant for combustion by-products. Sometimes the simplest really sure way to tell is to drive the car hot, park it overnight, then start it cold in the morning and run it for just a few seconds, then shut it off and go to the rear of the car and smell the exhaust. If it smells like coolant, you have head leakage.

[blk987]

The leakdown test is good for iron engines but not definitive on an all-aluminum engine. The head can seal when the engine is cold or running but not pulling a lot of torque until the leak gets pretty bad, after which the car will show lots of other obvious signs like constant overheating on the highway. The definitive test for Northstars is testing the coolant for combustion by-products. Sometimes the simplest really sure way to tell is to drive the car hot, park it overnight, then start it cold in the morning and run it for just a few seconds, then shut it off and go to the rear of the car and smell the exhaust. If it smells like coolant, you have head leakage.

Thank you. you always have some good info. Im going to get the kit for the combustion by products and try that. I think Im just in denial, I know Im going to de digging into these heads this weekend.

[BodybyFisher]

The leakdown test is good for iron engines but not definitive on an all-aluminum engine. The head can seal when the engine is cold or running but not pulling a lot of torque until the leak gets pretty bad, after which the car will show lots of other obvious signs like constant overheating on the highway. The definitive test for Northstars is testing the coolant for combustion by-products. Sometimes the simplest really sure way to tell is to drive the car hot, park it overnight, then start it cold in the morning and run it for just a few seconds, then shut it off and go to the rear of the car and smell the exhaust. If it smells like coolant, you have head leakage.

Thank you. you always have some good info. Im going to get the kit for the combustion by products and try that. I think Im just in denial, I know Im going to de digging into these heads this weekend.

Not to blow my own horn, but while the info Jim gave you is great, I posted this in Post #9 within this thread on October 16th, about a month ago:

Ok, then, you can buy a test kit to test for combustion by products in your coolant OR, you can go to a good radiator shop and have them test the coolant for combustion by products.

NAPA sells a kit that you can buy to test your coolant, as a final conclusion you should test your coolant

However, it does not sound good so far, the smell in the tank and brief misfire are symptoms of a leaking head gasket

[winterset]

No, as mentioned a block test kit will diagnose it, but a compression test will tell you nothing about a head gasket. A leak down test is what is needed.

Hey there its been a while and maybe I should have started a new thread but I wasnt sure. The car is still sitting I have been too busy. Although i did get around to doing the leak down test like you said and the results came out fine. All cylinders tested good. I followed the instructions perfectly I put each cylinder at TDC, the motor was warmed up before testing and it just doesnt make sense to me. I did have another member tell me that if the head bolts are pulled enough that it will give a false reading which does make sense but before I dive into the heads I was looking for any suggestions to determining faulty gaskets(other than going to an engine shop). I do not have a couple of the definite signs like white smoke or bubbles in the coolant reservoir the only signs are overheating and a major loss of coolant externally so Im kinda at a loss on what to do next. If anyone could please help Im ready to get back behind the wheel of her.

Where are you loosing the coolant? is it gurgling out of the overflow tank after you overheat? You explain it as if you have a major external leak in your cooling system. If that is the case that will explain your overheating issue. Not sure if I am missing something - but there are many hoses & crossovers back there that can cause a leak. although I am not sure how it will not reveal itself in a pressure test. I am remaining optomistic it's just a leak.

[blk987]

No, as mentioned a block test kit will diagnose it, but a compression test will tell you nothing about a head gasket. A leak down test is what is needed.

Hey there its been a while and maybe I should have started a new thread but I wasnt sure. The car is still sitting I have been too busy. Although i did get around to doing the leak down test like you said and the results came out fine. All cylinders tested good. I followed the instructions perfectly I put each cylinder at TDC, the motor was warmed up before testing and it just doesnt make sense to me. I did have another member tell me that if the head bolts are pulled enough that it will give a false reading which does make sense but before I dive into the heads I was looking for any suggestions to determining faulty gaskets(other than going to an engine shop). I do not have a couple of the definite signs like white smoke or bubbles in the coolant reservoir the only signs are overheating and a major loss of coolant externally so Im kinda at a loss on what to do next. If anyone could please help Im ready to get back behind the wheel of her.

Where are you loosing the coolant? is it gurgling out of the overflow tank after you overheat? You explain it as if you have a major external leak in your cooling system. If that is the case that will explain your overheating issue. Not sure if I am missing something - but there are many hoses & crossovers back there that can cause a leak. although I am not sure how it will not reveal itself in a pressure test. I am remaining optomistic it's just a leak.

Im leaking coolant while Im driving before it overheats and before it sends the shut off engine message it is literally pouring out of the overlow reservoir. The upper radiator hose is full to its max with either hot air from the exhaust or coolant but I could never figure out which. Even though the car is already in the garage half taken apart something still tells me its not the heads. Its entire life so far was driven by my father in law who took great car of it and all maintenance was performed at a Caddy dealer. Im still in denial about the head gaskets...

[CarlaValentine]

No, as mentioned a block test kit will diagnose it, but a compression test will tell you nothing about a head gasket. A leak down test is what is needed.

Hey there its been a while and maybe I should have started a new thread but I wasnt sure. The car is still sitting I have been too busy. Although i did get around to doing the leak down test like you said and the results came out fine. All cylinders tested good. I followed the instructions perfectly I put each cylinder at TDC, the motor was warmed up before testing and it just doesnt make sense to me. I did have another member tell me that if the head bolts are pulled enough that it will give a false reading which does make sense but before I dive into the heads I was looking for any suggestions to determining faulty gaskets(other than going to an engine shop). I do not have a couple of the definite signs like white smoke or bubbles in the coolant reservoir the only signs are overheating and a major loss of coolant externally so Im kinda at a loss on what to do next. If anyone could please help Im ready to get back behind the wheel of her.

Where are you loosing the coolant? is it gurgling out of the overflow tank after you overheat? You explain it as if you have a major external leak in your cooling system. If that is the case that will explain your overheating issue. Not sure if I am missing something - but there are many hoses & crossovers back there that can cause a leak. although I am not sure how it will not reveal itself in a pressure test. I am remaining optomistic it's just a leak.

Im leaking coolant while Im driving before it overheats and before it sends the shut off engine message it is literally pouring out of the overlow reservoir. The upper radiator hose is full to its max with either hot air from the exhaust or coolant but I could never figure out which. Even though the car is already in the garage half taken apart something still tells me its not the heads. Its entire life so far was driven by my father in law who took great car of it and all maintenance was performed at a Caddy dealer. Im still in denial about the head gaskets...

I have read through this whole thread, but I have already forgotten if this was mentioned or not: Have you replaced your coolant tank cap? Or checked that it is on ALL the way? This sounds an awful lot to me like the cap isn't holding pressure and is allowing the coolant to boil out of the overflow hose.

[BodybyFisher]

Carla, in post number 3, he stated that he replaced the cap