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My Overheating problem...


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You can see the T in this photo from when I replaced my heater pipes on my 96

CrossoverJob034.jpg

I Hate those pipes with a passion. Pain in the butt to replace, and sometimes hard to diagnose

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I have been following the last 2 overheating post closely for my 97sls has had a overheating problem this might be a little premature but here are my findings.

Car would overheat at idle 90+ weather at speed it ran fine I have the temp read out so Im able to monitor it closely. It would also lose coolant.

Thanks to members on this site here is what i did. Checked surge tank for bubbles none next surge line for flow good Heater for heat ok. Ran engine with cap off coolant boiled at 215 degrees. So far no cost.

Went to auto zone rented radiator pressure tester and block tester. System pressure held at 15psi for 5 min. did find a small leak at upper radiator hose tighten clamp no leak. Radiator cap would not hold pressure at all.

Did a block test liquid stayed blue went back to auto zone tested new cap it would open at 13 psi. Retested old cap pressure would drop. Installed new cap in car.

Conclusion cap would allow coolant to boil over if it got to 215 degrees loosing coolant would only allow situation to get worse. Ruled out HG failure. Will take a test drive today although temp is in the seventy's it may not be possible to duplicate problem.

One note here if the block test turns yellow clean the tester with fresh water and re test the reason the person who used the tester before you might not have cleaned the tester if they got a yellow result. This is a clear warning in the instructions I would buy a new unopened tester if I still got a yellow just for a second opinion.

I'm not going to assume my problem is solved there might be a mechanical issue but I will be monitoring the temp closely I'm fortunate to have a temp read out on the drivers information center. Thanks to everyone.Mike

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This is good patient diagnostics Mike, good job!

Pre-1995 - DTC codes OBD1  >>

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

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Road test yesterday about 12 miles 65degrees between 40 and 75mph. Temp never went above 206. Back in garage idled in gear temp went to 226 fans kicked in temp went down. I never paid close attention to the analog gauge but as I waited for the fans to cycle the gauge moved about 3/16 of a inch before the fans kicked in. Did this twice second time fans kicked in at 222 degrees.

Checked surge tank for coolant loss it look ok. Coolant good to minus 10 degrees added pure antifreeze to tank as much as I dared, do not want to overfill.

Note Autozone put my deposit back in my credit card account when I returned the pressure tester. I'm holding on to the block tester would like to do a couple more checks before I return it. I feel fairly certain if you bring your cap to autozone they will check it as a courtesy.

A added plus to the pressure/block test is that you can feel fairly comfortable putting money into other repairs knowing at that moment the chances of a HG repair are slim. I wonder how many times a shop replaced a radiator/water pump when the problem was the cap.Mike

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That is why we say to pressure test the system and cap. Our high school science tells us that water at sea pressure boils lower than water under pressure, its the first place to check and it eliminates a LOT of other stuff.

The tools you rented should be in every good mechanics tool box

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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Road test yesterday about 12 miles 65degrees between 40 and 75mph. Temp never went above 206. Back in garage idled in gear temp went to 226 fans kicked in temp went down. I never paid close attention to the analog gauge but as I waited for the fans to cycle the gauge moved about 3/16 of a inch before the fans kicked in. Did this twice second time fans kicked in at 222 degrees.

Checked surge tank for coolant loss it look ok. Coolant good to minus 10 degrees added pure antifreeze to tank as much as I dared, do not want to overfill.

Note Autozone put my deposit back in my credit card account when I returned the pressure tester. I'm holding on to the block tester would like to do a couple more checks before I return it. I feel fairly certain if you bring your cap to autozone they will check it as a courtesy.

A added plus to the pressure/block test is that you can feel fairly comfortable putting money into other repairs knowing at that moment the chances of a HG repair are slim. I wonder how many times a shop replaced a radiator/water pump when the problem was the cap.Mike

I tried to test my caps (I have 2 I've been alternating) with the pressure tester, but I was not convinced the attachment made a good seal on the pump. As a result, both caps quickly bled off pressure. Neither the pump or the cap seemed to make a good seal with the adapter, so I don't know what to think about that.

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Road test yesterday about 12 miles 65degrees between 40 and 75mph. Temp never went above 206. Back in garage idled in gear temp went to 226 fans kicked in temp went down. I never paid close attention to the analog gauge but as I waited for the fans to cycle the gauge moved about 3/16 of a inch before the fans kicked in. Did this twice second time fans kicked in at 222 degrees.

Checked surge tank for coolant loss it look ok. Coolant good to minus 10 degrees added pure antifreeze to tank as much as I dared, do not want to overfill.

Note Autozone put my deposit back in my credit card account when I returned the pressure tester. I'm holding on to the block tester would like to do a couple more checks before I return it. I feel fairly certain if you bring your cap to autozone they will check it as a courtesy.

A added plus to the pressure/block test is that you can feel fairly comfortable putting money into other repairs knowing at that moment the chances of a HG repair are slim. I wonder how many times a shop replaced a radiator/water pump when the problem was the cap.Mike

I tried to test my caps (I have 2 I've been alternating) with the pressure tester, but I was not convinced the attachment made a good seal on the pump. As a result, both caps quickly bled off pressure. Neither the pump or the cap seemed to make a good seal with the adapter, so I don't know what to think about that.

Mike: if you could comment on how you tested your cap, I would appreciate it.

I got my pressure tester from AutoZone as well. To test the cap, I attached the silver adapter to the pump, but as stated, it didn't seem to make a firm seal. Certainly not as tight as it was on the surge tank. I put the cap on the other end of the adapter, and again, it didn't seem very tight. Pumped up the pressure to about 12psi, and it immediately began bleeding off. I'm not sure if it was a poor seal on the cap and pump, or a bad cap.

Based on your over-heating scenario, I am wondering if the cap is a player in my problem. My car passed both the cold and engine running tests with the pump, leading me to believe the HG is not the issue. I was, however, losing modest amounts of coolant in daily driving. Your situation makes me think a faulty cap may have been leading to my gradual loss of coolant, not a leaking HG. I just want to test the cap properly, and I don't think the pump/attachments I got from AZ are providing that.

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Mike I am sorry to hear about your tester not appearing to seal good, I still think that testing the cap is a worthy thing to do and hope that you have solved your overheating problem.

They like the thermostat are cheap enough just to replace every 2 or 3 years, if you know what I mean to ensure that their calibration is accurate

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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Tried testing my caps again, and this time it seemed to work.

The new cap (16psi) would release at what looked like about 14-15 on the gauge, then settle back to holding around 12psi.

The old cap bled out air immediately.

For the record, I decided to idle test the car once again before taking the pressure tester back. The results were similar, with a few quirks.

The "test" is supposed to be at idle with normal operating temps. Under those conditions, the psi was running right around 7. Decided to rev the engine and observe the effects on the needle. First, let me say that revving the engine steady when the temp rose to 215, lowered the temp to 196 in about a minute. The needle on the pump would lower in psi as the temp dropped. This again seems to point to coolant "flow", as I was not moving, nor were the fans engaged yet. I also did some 4000rpm punches a few minutes later.

Oddly, the car then sat at 206 degrees for probably 6-7 minutes as 650 rpm idle. This is totally contrary to the "minute to minute" build up in temps that the car usually experiences at idle. I noticed the heater warming slightly. I then decided to do a few more high revs, let the car return to idle, and then the temp began to rise. It rose to about 228 before I shut it down. The psi never spiked, but it did rise to about 12. That would seem to correlate with the cap releasing pressure at about 250 degrees, when the psi reaches it't limits.

Don't know if I really learned anything new. The car goes in tomorrow for heater/coolant flushes and a check of the belt and tensioner.

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I too was unsure of the tester holding pressure with the adapter and the cap because there was no gasket between the tester and the adapter so when I went back to autozone we got another kit sure enough it did not have a gasket.

So I Tested a new cap to compare, it let go at 13 lbs. and held there. The way I used the tester is I put on the adapter turning clockwise the same with the cap tuned butterfly on cap clockwise made sure system was solid and then pumped. Released the butterfly installed old cap it would not hold pressure. Worked great.Mike

Think I should edit here. After I put on the old cap I tested it the same way as the new cap don't want to confuse anyone.Mike

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Imacad I have reread the post again I'm fairly certain you don't have a HG problem but I would do the block test any way also recheck the surge line again. Ask the parts guy at autozone for block tester 27145.

My fans kick in between 222 and 226 so 228 is in the ball park check your coolant often, the proper mix of coolant should add 4 degrees to the boiling point. With the surge line flow, the cap working, system holding pressure, fans kicking in and a block test you are free to start looking for mechanical/flow issues.

The one thing we haven't addressed in detail is your heater core and low coolant light. After your coolant flush you might want to revisit these issues and fix them as recommended by members on this post. Mike

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I have a 2000 SLS and am 1500 miles from home. The engine hot light came on and I drove about 300 miles with the temp and fan cranked up on high. The Caddy dealer diagnosed and found CO gasses in the cooling system, indicating a head gasket leak. The estimate was $4400, but I can get it fixed back home for $1300. Am I safe putting Bars Head Gasket repair in the cooloant and babying it on the way home, or are there any other ideas out there?

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I have a 2000 SLS and am 1500 miles from home. The engine hot light came on and I drove about 300 miles with the temp and fan cranked up on high. The Caddy dealer diagnosed and found CO gasses in the cooling system, indicating a head gasket leak. The estimate was $4400, but I can get it fixed back home for $1300. Am I safe putting Bars Head Gasket repair in the cooloant and babying it on the way home, or are there any other ideas out there?

How hot is it getting?

You can do a test and try the bars and we usually don't have any confidence in bottled repairs.

Carry coolant in the trunk

Avoid Traffic, travel in the cool air if possible and keep moving

BEFORE you get it repaired come back you need to do the CORRECT repair, and it costs about $1000 to do it yourself, its darn near impossible to do this job for $1300 and make enough money on it to not go out of business, its a HUGE job!!!!!

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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The Good, the Bad, and the Ugly..

The Good: Took the car in for the flushes of coolant system and heater core. Heater core flushed with little gunk. Coolant system flushed with only a little gunk. Water pump belt was very worn and needed replaced. Figured it to be the culprit.

Also, a block test was done, and there were no exhaust gases in the coolant.

The Bad: After the flushes were done, and the belt replaced, the over heating problem was actually worse! The heater core is clear, but still very little heat. White gunk bubbling up into surge tank, presumably the residue of a seal job gone bad getting pushed back into the tank when the car overheats.

The Ugly Running out of guesses. Good to know the head gaskets are OK, but what may have fixed that may be causing other problems.

As of now, we are going to remove the surge tank and try to verify that the hose that drops down to the "T" where coolant exits from the heater is clear. If the heater core is clear, bu there is still no heat then a hose going in or out must be blocked (right?), and if we can solve that, maybe we can fix this beast. Maybe there is a clog at the point where the coolant system sends coolant to the heater, back on the driver side of the engine.

Will make sure the purge line gets re-checked. Will also check the thermostat, although it's only about 4 months old.

If you have any suggestions where to look next, let me know.

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My guess is that your purge line is clogged, remove the bolt with a hole in it and look at it to see if its clear, use a 15mm wrench, it takes 5 minutes

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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Air pockets? Run it shut it down repeat a no. of times do not let it overheat and like bbf says keep checking the purge line.Mike

In addition to all the flushing, the mechanic then put a vacuum on the coolant system to draw out any extraneous air. After he did so, he cleared space for another gallon of coolant, so there was definitely an air bubble. The car tested pretty good after that. We called it good at that point.

The heater is still pretty much out of commission. The engine temps are running close to the best I've seen the car operate at; 197-201 in city traffic, with an occasional pop up to 215. That's alleviated when you get moving. For the most part, it seems the problem has been remedied. I guess we'll see on that.

I did notice that I was venting a bit of coolant when I parked the car yesterday, despite the fact the temp never got over 220. I thought what was spilling out looked a bit thin on the coolant ratio, but I haven't re-tested it. Cleaned the radiator cap. It was rimmed with particulates from what had been bubbling out. May need a new cap, may need to ante up the pure coolant. With all the flushing the car went through, they may not have gotten the proper coolant ratio in the system.

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I dont see where you have checked the purge line for flow.

Also was the block test done before or after the flushes?

cant find my pic to show the bolt with the hole in it, but will post another

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I dont see where you have checked the purge line for flow. That has been done several times

Also was the block test done before or after the flushes? Two block tests were done after the flush

cant find my pic to show the bolt with the hole in it, but will post another

Drew some coolant out of the surge tank this morning, and it looked almost completely like water. Would gauge it to be only 10-20% coolant. Tank was completely full, and had purged some of the mix out the overflow after it was parked. It was not leaking anything when I had stopped the car the night before. Temps read about 210 as I parked.

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

After multiple flushes, it appears the guys at the shop lost track of what was in the coolant system when they called the job done. Don't know if the almost pure water mix would have caused the tank to rise and overflow by itself. Will take the car back and get the coolant mix fixed tomorrow.

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This is the problem with flushing a cooling system and the reason why the guru stated that is should not be done.

Because they are flushing with water, water gets into the engine, some of that water is not drained when the cooling system is drained, and you have straight water in the engine, heater core, pipes etc.

Its difficult to get the system back to 50/50 at that point

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.

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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

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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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.

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