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Overheating? Why?


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A couple of days ago, I got a call from someone I met from Craigslist who was selling a 96 STS. His friend had a 97 Eldorado and it was overheating

His mechanic replaced:

The Radiator because he said "it was only cooling at 50%" blink.gif

The Radiator Hoses

The Water Pump

"Sealed the coolant tank" with some sort of sealer blink.gif (I advised that they replace the tank)

He for some reason did not replace the thermostat

He was going to pull out the radiator again to "have a look" at it (Have a look at it? blink.gif )

and then he said it "MUST be the head gasket"..... fighting0025.gif

He had "consulted" with his friends and concluded HEAD GASKET biggrin.gif

I said, is the engine running rough? NO

Do you have smoke out of the exhaust? NO

Does the coolant tank smell like exhaust fumes? NO

Pull the purge line off of the tank and see if there is any coolant flowing.... NO COOLANT FLOWING Laie_22mini.gif

I went there today with my tools, pulled the "bolt with a hole in it" and it was clogged with rubber/silicone gasket material, a 2 1/2 inch piece was stuck in the orfice... yupi3ti.gif

I cleared the orfice, put it back together and they took it for a ride and the TEMP GAGE stayed at 12 o'clock... it does not appear to be overheating, but they will take it for a long ride and advise.

Let this be a lesson to us all, NEVER ASSUME head gasket without doing ALL DIAGNOSIS...

Another Cadillac saved!

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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Good job, Mike.

I am always glad to hear of another Cadillac saved.

It is too bad that (so called) mechanics don't have to refund the money they gyp people out of because they don't know what the heck they are doing.

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I agree,

I said don't blame the mechanic, the mechanic did all he could, but he does not work on Northstars, and I have unique experience to tackle a problem like this.

It made me feel GREAT that I was able to diagnose and solve this problem, initally OVER THE PHONE, laugh.gif

I am going back to replace their coolant tank, dog bones and put 4 cooling supplement tablets in....

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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Here is the silicone that clogged the purge line, it was twice as long as this, I gave the owner half of it to keep, it was about 2 inches long..and fully stuck into the orfice and about 1/2 inch was sticking out

PurgeLineClog.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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Let this also be a lesson to not put any kind of "sealant" in the coolant tank..... I assume that is what caused the clog?

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No that was not from the coolant tank, that was from the water pump job, they used a hardening epoxy on the tank

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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Silicone on a water pump job?

I have assumed that they used silicone on the water pump body seal at the back, that is the only place I think that a mechanic might consider using it

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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Here is the silicone that clogged the purge line, it was twice as long as this, I gave the owner half of it to keep, it was about 2 inches long..and fully stuck into the orfice and about 1/2 inch was sticking out

PurgeLineClog.jpg

Good job, Mike. There are probably more pieces like that which will potentially cause problems in the future.

The saddest thing in life is wasted talent

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Thanks Adallak, that is a good point and one that I will remind them to keep an eye out for

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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i have a 04 deville overheating check the heat by cutting it on it blow out cold air im pretty sure it the thermostat but i need help finding where it located and how to change it

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I agree,

I said don't blame the mechanic, the mechanic did all he could, but he does not work on Northstars, and I have unique experience to tackle a problem like this.

It made me feel GREAT that I was able to diagnose and solve this problem, initally OVER THE PHONE, laugh.gif

I am going back to replace their coolant tank, dog bones and put 4 cooling supplement tablets in....

Excellent diagnosis! I do blame the mechanic that did all the unnessary work though. If a shop does not have expierence working on these cars, they should not attempt the repair. That shop probably charged the guy $500+ to replace perfectly good parts. I wonder how much he would have charged to replace the good head gaskets??? The car owner should ask for his original radiator back as a spare.

i have a 04 deville overheating check the heat by cutting it on it blow out cold air im pretty sure it the thermostat but i need help finding where it located and how to change it

Check the heater hose temps - the heater hoses enter the firewall near the center - right below the pivot point of the passenger side wiper arm. If the inlet is hot and the outlet hose is slightly cooler than the inlet, the thermostat is probably fine. If they are both the same temperature, the heater core could be clogged.

The thermostat is behind where the radiator outlet hose enters the water pump housing - look below the water pump belt guard and just rearward of the engine oil dipstick.

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

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An update on this, the owner has driven the car on short trips and it has been fine, he is calling me when the parts come in...

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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I agree,

I said don't blame the mechanic, the mechanic did all he could, but he does not work on Northstars, and I have unique experience to tackle a problem like this.

It made me feel GREAT that I was able to diagnose and solve this problem, initally OVER THE PHONE, laugh.gif

I am going back to replace their coolant tank, dog bones and put 4 cooling supplement tablets in....

Excellent diagnosis! I do blame the mechanic that did all the unnessary work though. If a shop does not have expierence working on these cars, they should not attempt the repair. That shop probably charged the guy $500+ to replace perfectly good parts. I wonder how much he would have charged to replace the good head gaskets??? The car owner should ask for his original radiator back as a spare.

i have a 04 deville overheating check the heat by cutting it on it blow out cold air im pretty sure it the thermostat but i need help finding where it located and how to change it

Check the heater hose temps - the heater hoses enter the firewall near the center - right below the pivot point of the passenger side wiper arm. If the inlet is hot and the outlet hose is slightly cooler than the inlet, the thermostat is probably fine. If they are both the same temperature, the heater core could be clogged.

The thermostat is behind where the radiator outlet hose enters the water pump housing - look below the water pump belt guard and just rearward of the engine oil dipstick.

Somewhere I read to be sure the thermostat was placed in the correct upward position. Upon looking at the thermostat plate, there is a little hole with a loose plug in the hole, like some kind of airvent . . . Does it matter the thermostat's position when installing ?

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I agree,

I said don't blame the mechanic, the mechanic did all he could, but he does not work on Northstars, and I have unique experience to tackle a problem like this.

It made me feel GREAT that I was able to diagnose and solve this problem, initally OVER THE PHONE, laugh.gif

I am going back to replace their coolant tank, dog bones and put 4 cooling supplement tablets in....

Excellent diagnosis! I do blame the mechanic that did all the unnessary work though. If a shop does not have expierence working on these cars, they should not attempt the repair. That shop probably charged the guy $500+ to replace perfectly good parts. I wonder how much he would have charged to replace the good head gaskets??? The car owner should ask for his original radiator back as a spare.

i have a 04 deville overheating check the heat by cutting it on it blow out cold air im pretty sure it the thermostat but i need help finding where it located and how to change it

Check the heater hose temps - the heater hoses enter the firewall near the center - right below the pivot point of the passenger side wiper arm. If the inlet is hot and the outlet hose is slightly cooler than the inlet, the thermostat is probably fine. If they are both the same temperature, the heater core could be clogged.

The thermostat is behind where the radiator outlet hose enters the water pump housing - look below the water pump belt guard and just rearward of the engine oil dipstick.

Somewhere I read to be sure the thermostat was placed in the correct upward position. Upon looking at the thermostat plate, there is a little hole with a loose plug in the hole, like some kind of airvent . . . Does it matter the thermostat's position when installing ?

I responded to this question on your other thread PLEASE only post your question in ONE PLACE, this posting was not necessary and it was OFF TOPIC here.. Ill delete this later

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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Really nice work in finding the true cause of the overheating!

Many people over here seem to rely on and trust in shady tree "mechanics".

For instance one of the members bought a STS from an owner who had the car "serviced" at a cost of almost $10000 for the last year only!

People over here seems to think that it should cost to service a Cadillac and sees nothing wrong in paying insane amounts of cash for "service".

Then they go on about the bad quality in american cars.

I am however not willing to pay for an automatic transmission when it is enough to change the shift solenoids or for that matter a new engine when a hose is clogged!

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Really nice work in finding the true cause of the overheating!

Many people over here seem to rely on and trust in shady tree "mechanics".

For instance one of the members bought a STS from an owner who had the car "serviced" at a cost of almost $10000 for the last year only!

People over here seems to think that it should cost to service a Cadillac and sees nothing wrong in paying insane amounts of cash for "service".

Then they go on about the bad quality in american cars.

I am however not willing to pay for an automatic transmission when it is enough to change the shift solenoids or for that matter a new engine when a hose is clogged!

I agree 100% Jan, diagnosis of problems requires clear communication between the owner and the mechanic fixing the car, I believe having a service writer in between those individuals creates room for miscommunication. This is especially true if the service writer is not experienced or if the information is not communicated correctly. This is compounded by 'garage' mechanics that work on all types of cars, and not exclusively the Northstar, and their quick conclusion that its a head gasket problem without proper diagnosis.

I am beginning to see my value, now if I could only convince GM/Cadillac that I would make a great service writer......

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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Really nice work in finding the true cause of the overheating!

Many people over here seem to rely on and trust in shady tree "mechanics".

For instance one of the members bought a STS from an owner who had the car "serviced" at a cost of almost $10000 for the last year only!

People over here seems to think that it should cost to service a Cadillac and sees nothing wrong in paying insane amounts of cash for "service".

Then they go on about the bad quality in american cars.

I am however not willing to pay for an automatic transmission when it is enough to change the shift solenoids or for that matter a new engine when a hose is clogged!

I agree 100% Jan, diagnosis of problems requires clear communication between the owner and the mechanic fixing the car, I believe having a service writer in between those individuals creates room for miscommunication. This is especially true if the service writer is not experienced or if the information is not communicated correctly. This is compounded by 'garage' mechanics that work on all types of cars, and not exclusively the Northstar, and their quick conclusion that its a head gasket problem without proper diagnosis.

I am beginning to see my value, now if I could only convince GM/Cadillac that I would make a great service writer......

Did you know that the "mechanics" wanted almost $5600 for a new navigation system to one of the guys in our sub-forum. It was enough to reload the software through a CD...now if I had asked for 50% of the shop fee :D

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Amazing isnt it?

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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Really nice work in finding the true cause of the overheating!

Many people over here seem to rely on and trust in shady tree "mechanics".

For instance one of the members bought a STS from an owner who had the car "serviced" at a cost of almost $10000 for the last year only!

People over here seems to think that it should cost to service a Cadillac and sees nothing wrong in paying insane amounts of cash for "service".

Then they go on about the bad quality in american cars.

I am however not willing to pay for an automatic transmission when it is enough to change the shift solenoids or for that matter a new engine when a hose is clogged!

I agree 100% Jan, diagnosis of problems requires clear communication between the owner and the mechanic fixing the car, I believe having a service writer in between those individuals creates room for miscommunication. This is especially true if the service writer is not experienced or if the information is not communicated correctly. This is compounded by 'garage' mechanics that work on all types of cars, and not exclusively the Northstar, and their quick conclusion that its a head gasket problem without proper diagnosis.

I am beginning to see my value, now if I could only convince GM/Cadillac that I would make a great service writer......

Just refer them here...then they can see how valuable of an asset you could be to them. Just don't leave us behind if that day comes. smile.gif

big4870885.jpg

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Thanks

That would never happen

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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Thanks

That would never happen

Me neither. It's (almost) always good to help someone and it is also a good way of spreading out REAL technical information about our vehicles!

Besides the fact that I'm a do-it-yourself kind of person it is always good to set a "mechanic" straight...

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If I had the know-how and the money I would definitely look into becoming a mechanic specializing in Cadillacs, and open my own shop. There are a lot of Cadillacs around here (3 other than mine just on the block I live on), and not a single shop that knows much about them. The closest dealership is a 45 minute drive from here.

Who knows? Maybe someday...I am still pretty young.

In the meantime, I think I'll hang out here and learn, and do my best to help out where and when I can.

big4870885.jpg

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  • 5 years later...

I agree,

I said don't blame the mechanic, the mechanic did all he could, but he does not work on Northstars, and I have unique experience to tackle a problem like this.

It made me feel GREAT that I was able to diagnose and solve this problem, initally OVER THE PHONE, laugh.gif

I am going back to replace their coolant tank, dog bones and put 4 cooling supplement tablets in....

Excellent diagnosis! I do blame the mechanic that did all the unnessary work though. If a shop does not have expierence working on these cars, they should not attempt the repair. That shop probably charged the guy $500+ to replace perfectly good parts. I wonder how much he would have charged to replace the good head gaskets??? The car owner should ask for his original radiator back as a spare.

i have a 04 deville overheating check the heat by cutting it on it blow out cold air im pretty sure it the thermostat but i need help finding where it located and how to change it

Check the heater hose temps - the heater hoses enter the firewall near the center - right below the pivot point of the passenger side wiper arm. If the inlet is hot and the outlet hose is slightly cooler than the inlet, the thermostat is probably fine. If they are both the same temperature, the heater core could be clogged.

The thermostat is behind where the radiator outlet hose enters the water pump housing - look below the water pump belt guard and just rearward of the engine oil dipstick.

Somewhere I read to be sure the thermostat was placed in the correct upward position. Upon looking at the thermostat plate, there is a little hole with a loose plug in the hole, like some kind of airvent . . . Does it matter the thermostat's position when installing ?

I responded to this question on your other thread PLEASE only post your question in ONE PLACE, this posting was not necessary and it was OFF TOPIC here.. Ill delete this later

What would happen if the thermostat was installed in the wrong position... Oh by the way I read that it is important to install it in the proper position but what is that position?

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