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My Overheating problem...


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Someone please post a pic of the bolt with the hole in it, because if that bolt isnt flowing the system has no way to purge the air

I looked all over the manual and could not find a photo, but I trust its the same as my 96 since the engine is swapable. I was under the impression that the bolt with a hole in it was REMOVED and cleaned, if it has NOT been REMOVED and cleaned at this point for the elimination of it being responsible for problems, it should be, find it, disconnect the hose from it and remove the 'bolt with a hole in it" and look to see that the ORFICE is clear if not clear it. It takes a few minutes to do this. In this photo its the small circle at 2 o'clock

WaterPumpandRadiator022-1.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Don't know if the almost pure water mix would have caused the tank to rise and overflow by itself.

No it would not.

Started up and revved the engine a few times to burp the system. Some of the mix splashed out as I did so.

Not a good sign. Agree, but then the car has passed 4 pressure tests and 2 block tests in the past week alone.

Hmm, that's strange, but the more I think of it, that could happen IF the purge line is clogged.

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Don't know if the almost pure water mix would have caused the tank to rise and overflow by itself.

No it would not.

Started up and revved the engine a few times to burp the system. Some of the mix splashed out as I did so.

Not a good sign. Agree, but then the car has passed 4 pressure tests and 2 block tests in the past week alone.

Hmm, that's strange, but the more I think of it, that could happen IF the purge line is clogged.

It's not clogged, at least not at the bolt. It has been checked 3-4 times the past week, amid all the flushes and re-flushes. I guess I could re-check the purge line at the tank.

For the record:

Car is currently running 197-210 in city driving. If you have been on the highway or driving in town for more than 20-30 minutes, the temp wants to creep into the teens at a stop. The temp then drops back down as you pull away.

I'll probably test the ability of the fans to regulate temperature at a stop to no more than 230. I know that revving the engine if the temp gets to 230 will lower the temp, but I would like to see the car self-regulate.

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Hmm, that's strange, but the more I think of it, that could happen IF the purge line is clogged.

It's not clogged, at least not at the bolt. It has been checked 3-4 times the past week, amid all the flushes and re-flushes. I guess I could re-check the purge line at the tank.

For the record:

Car is currently running 197-210 in city driving. If you have been on the highway or driving in town for more than 20-30 minutes, the temp wants to creep into the teens at a stop. The temp then drops back down as you pull away.

I'll probably test the ability of the fans to regulate temperature at a stop to no more than 230. I know that revving the engine if the temp gets to 230 will lower the temp, but I would like to see the car self-regulate.

Your temps seem normal now...

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It's not clogged, at least not at the bolt. It has been checked 3-4 times the past week, amid all the flushes and re-flushes. I guess I could re-check the purge line at the tank.

Well, if the purge line is clear, then I can't see that pointing to anything but a failed HG.

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It's not clogged, at least not at the bolt. It has been checked 3-4 times the past week, amid all the flushes and re-flushes. I guess I could re-check the purge line at the tank.

Well, if the purge line is clear, then I can't see that pointing to anything but a failed HG.

So after all that and normal temps,still a HG issue?

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It's not clogged, at least not at the bolt. It has been checked 3-4 times the past week, amid all the flushes and re-flushes. I guess I could re-check the purge line at the tank.

Well, if the purge line is clear, then I can't see that pointing to anything but a failed HG.

But Ranger... the temps are normal now... it is not overheating... at least not at the present time.

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Well, he had and is still having temperature problems. "Car is currently running 197-210 in city driving. If you have been on the highway or driving in town for more than 20-30 minutes, the temp wants to creep into the teens at a stop. The temp then drops back down as you pull away." While that is not overheating, the fluctuation is not normal (from my observations any way). Then he said "Started up and revved the engine a few times to burp the system. Some of the mix splashed out as I did so". I read that to mean that there was "air" in the system that pushed the coolant out via the bottom surge tank hose as opposed to the purge line. If I understand him correctly, where else could that "air" have come from? The purge line should have purged any air from the flushes. The only other explanation I can think of is if the coolant splashed out AFTER he revved it and the RPM's where coming down and the coolant then surged back into the tank because the lowering RPM's where not sucking coolant from the tank anymore. If that's the case, then I would retract that statement.

EDIT:

Went back and reread post #71 where he said "tank was completely full". That may explain what I just said above. That said, what was the fix? Did I miss it? What brought the temps back to normal?

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Well, he had and is still having temperature problems. "Car is currently running 197-210 in city driving. If you have been on the highway or driving in town for more than 20-30 minutes, the temp wants to creep into the teens at a stop. The temp then drops back down as you pull away." While that is not overheating, the fluctuation is not normal (from my observations any way). Then he said "Started up and revved the engine a few times to burp the system. Some of the mix splashed out as I did so". I read that to mean that there was "air" in the system that pushed the coolant out via the bottom surge tank hose as opposed to the purge line. If I understand him correctly, where else could that "air" have come from? The purge line should have purged any air from the flushes. The only other explanation I can think of is if the coolant splashed out AFTER he revved it and the RPM's where coming down and the coolant then surged back into the tank because the lowering RPM's where not sucking coolant from the tank anymore. If that's the case, then I would retract that statement.

EDIT:

Went back and reread post #71 where he said "tank was completely full". That may explain what I just said above. That said, what was the fix? Did I miss it? What brought the temps back to normal?

He cleared the purge line and it was still getting hot... there seems to be no water going thru the heater.

He had the entire system flushed multiple times and got a bunch of crud out of it.

Now the temps are fairly normal.

At least that is the way I read it...

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I can't remember any more,has a block test been performed? Does it have a rough idle in the morning,then clear?Is coolant being replenished?

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I can't remember any more,has a block test been performed? Does it have a rough idle in the morning,then clear?Is coolant being replenished?

Block test was done twice... if I remember right..it passed both times.

No rough idle.. no coolant loss except when it was over heating.

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He cleared the purge line and it was still getting hot... there seems to be no water going thru the heater.

He had the entire system flushed multiple times and got a bunch of crud out of it.

Now the temps are fairly normal.

Well then I retract that statement. Maybe just too much of that damned sealant tab residue in the radiator. That's probably what's clogging the heater core too. Maybe he's fine now.

These lengthy threads get hard to keep up with.

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He cleared the purge line and it was still getting hot... there seems to be no water going thru the heater.

He had the entire system flushed multiple times and got a bunch of crud out of it.

Now the temps are fairly normal.

Well then I retract that statement. Maybe just too much of that damned sealant tab residue in the radiator. That's probably what's clogging the heater core too. Maybe he's fine now.

These lengthy threads get hard to keep up with.

Yes, they do HG problem or not,it's not a new car and the process of the failure is slow, just drive on and get another one if you want. I would!

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He cleared the purge line and it was still getting hot... there seems to be no water going thru the heater.

He had the entire system flushed multiple times and got a bunch of crud out of it.

Now the temps are fairly normal.

Well then I retract that statement. Maybe just too much of that damned sealant tab residue in the radiator. That's probably what's clogging the heater core too. Maybe he's fine now.

These lengthy threads get hard to keep up with.

They sure do... :D :D

From what I remember of the description of what came out during the flushes, it probably had way, way, too many tabs put in it over the years.

To try to fix the heater, I would think he needs to take both heater hoses loose and try to flush it out that way.

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If the surge tank was completely full and the engine was revved up, I would expect it to overflow. The proper cold level is 2-1/2" below the bottom of the filler neck. I like the newer surge tanks that have a translucent lower half - it makes it much easier to get the coolant at the correct level.

The temps he reported are normal and the car is not overheating. It also passed the block test two times. I think the only thing wrong at this point is the heater core is plugged. It might need to be powerflushed at a radiator shop with hot water at 180 psi.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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If the surge tank was completely full and the engine was revved up, I would expect it to overflow. The proper cold level is 2-1/2" below the bottom of the filler neck. I like the newer surge tanks that have a translucent lower half - it makes it much easier to get the coolant at the correct level.

The temps he reported are normal and the car is not overheating. It also passed the block test two times. I think the only thing wrong at this point is the heater core is plugged. It might need to be powerflushed at a radiator shop with hot water at 180 psi.

180 PSI..... or .... 180 F....

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Wow, thanks for all the input guys.

I realize this has been a bit of a roller coaster ride, but just to summarize where I am today:

Temps: Highway 197; Stop and Go traffic 197-208; Extended Stop after 30 minutes of driving 212-215

Purge Line: Although it was plugged once about 30 days ago, it has never been plugged since. Probably has been checked 6-8 times since, just to make sure it didn't get re-plugged.

Heater: Delivers a modest amount of heat. For whatever reason, it seems to deliver a little more heat in the Auto position, as opposed to Auto Econ.

Block Tests: 2 done is past week, no combustion gasses detected on either

Pressure Tests: 4 done in past 10 days (2 cold, 2 engine running) All tests passed without any problem

Rough Idle at Start: Yes, the car frequently (about 75% of the time) has a rough idle at start, kind of like it's slightly flooded. It then seems to run normal after a minute or so. The Check Engine light is On. Have spent a fair amount of time thinking that was related to an HG problem, but since the car is not testing for that, it may be something else with the fuel system. If you have opinions on that, I'm all ears. Will pull the codes again. Those codes are P0420 - Speed Sensor on RR wheel. Might explain why the ABS light is on. The other current is C1235 Catalytic System inefficient. Might explain Check Engine light, don't know if it explains rough starts.

Coolant: The car currently has universal coolant in it. This initially had me thinking it was a very weak DexCool mix. The universal mix itself was a bit thin (-15), so we got it bumped to -30.

Thanks again for all the input.

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P0420 is the CAT and that is the reason your check engine light is on. You probably need a new cat and in my state you would not pass inspection.

The roughness after start up for a minute is due to the engine being in open loop. In open loop the system runs rich, like a choke in the old days, after a minute it goes into closed loop and the O2 sensors take over the process of setting the air/fuel ratio and the idle drops and levels out. A bad O2 sensor left inoperative for an extended amount of time can do damage to the CAT because a bad O2 sensor prevents the system from going into closed loop. So..the system runs rich all the time and the added heat burns up the CAT. So whenever you see an O2 sensor code or any problem that forces open loop, act on it.

Otherwise it sounds like your temps are perfect. I would reverse flush the heater core with a garden hose till it runs clear, it makes a big difference

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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180 PSI..... or .... 180 F....

180 PSI - it needs to be brought up to that pressure slowly. If the core clears out at a lower pressure then there is no need to increase it to 180. That is what radiator shops use to powerflush heater cores and radiators.

Radiator shops will backflush the core and then forward flush it, then backflush the core. Usually, that clears it out.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Wow, thanks for all the input guys.

I realize this has been a bit of a roller coaster ride, but just to summarize where I am today:

Temps: Highway 197; Stop and Go traffic 197-208; Extended Stop after 30 minutes of driving 212-215

Purge Line: Although it was plugged once about 30 days ago, it has never been plugged since. Probably has been checked 6-8 times since, just to make sure it didn't get re-plugged.

Heater: Delivers a modest amount of heat. For whatever reason, it seems to deliver a little more heat in the Auto position, as opposed to Auto Econ.

Block Tests: 2 done is past week, no combustion gasses detected on either

Pressure Tests: 4 done in past 10 days (2 cold, 2 engine running) All tests passed without any problem

Rough Idle at Start: Yes, the car frequently (about 75% of the time) has a rough idle at start, kind of like it's slightly flooded. It then seems to run normal after a minute or so. The Check Engine light is On. Have spent a fair amount of time thinking that was related to an HG problem, but since the car is not testing for that, it may be something else with the fuel system. If you have opinions on that, I'm all ears. Will pull the codes again. Those codes are P0420 - Speed Sensor on RR wheel. Might explain why the ABS light is on. The other current is C1235 Catalytic System inefficient. Might explain Check Engine light, don't know if it explains rough starts.

Coolant: The car currently has universal coolant in it. This initially had me thinking it was a very weak DexCool mix. The universal mix itself was a bit thin (-15), so we got it bumped to -30.

Thanks again for all the input.

In an attempt to wrap up this lengthy saga, I wanted to give you guys an update that I find rather interesting.

After flushing the coolant system and heater core out several times, the over-heating problem seemed to have moderated, but even though the heater appeared clear, there was still little or no heat.

Since the Check Coolant sensor seems to have shot craps (on all the time, even with surge tank at proper level), I am checking the tank to monitor the level fairly often. Checked it the other day, and was frustrated to see the level in the tank had dropped, even though I was detecting no visible leaks or overflows. The car had apparently gone through about a quart of coolant in about 30 miles of driving.

I somberly added some coolant and hopped in the car, and behold, the heater, which had not worked at all in recent weeks, was pumping warm air like a mofo.

By all accounts, whatever was blocking flow through the heater was now cleared, but the question is, "what was blocking the flow?"

I suppose it could be more of the gunk that came out of the system in the flushes, but if it was that, I suspect it would just move somewhere else, and create another over-heating issue. That has not been the case just yet. In fact, the car is now running at it's lowest temps since the time I bought it. It rarely reaches 200, and will operate at about 192 at steady speeds. I've put about 40 miles on the car around town since this occurrence.

Might there be an issue with how the coolant is added back to the system after a flush, that leads to an air lock in the hoses feeding and exiting the heater?

If there was gunk blocking the hose into the heater, wouldn't it have just move into the heater core and blocked things up there?

If there was something blocking the exit hose from the heater at the "T" below the surge tank, wouldn't you at least have heat from the coolant just sitting there in the core?

Kind of a mystery, but for now, I'm liking how the story ends. We'll see what develops.

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