dgladillac

06 sts overheating

10 posts in this topic

Hello forum I'm having an overheating problem on my 06 4.6 sts. Doesn't do it all the time but I'm afraid to drive it to far just incase. I pulled the hose off the coolant Resorvoir And Blew it out but I was reading about a hollow bolt on the waterpump housing somewhere. I can't seem to locate that. My fan comes on like it should and I haven't noticed any coolant leaking anywhere any help would be greatly appreciated. 

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12 hours ago, dgladillac said:

Hello forum I'm having an overheating problem on my 06 4.6 sts. Doesn't do it all the time but I'm afraid to drive it to far just incase. I pulled the hose off the coolant Resorvoir And Blew it out but I was reading about a hollow bolt on the waterpump housing somewhere. I can't seem to locate that. My fan comes on like it should and I haven't noticed any coolant leaking anywhere any help would be greatly appreciated. 

First off if you find that air purge line hose DO NOT blow it out.  If you read that on this board, please link me to it I need to correct that.  If the purge is clogged you need to go to the source and clear the clog there, blowing out the line from the tank side will only temporarily solve the problem. 

I don't know the 06 to well but I can not imagine them eliminating the air purge line.  Look at your coolant tank and look for a hose coming from the engine that is attached to the tank.  If you find it, gently take it off and direct it into a coffee can or container and start the car idle only, look, at the hose, coolant should flow, if not, its clogged.

If it is clogged come back and we will help.

Explain details, when does it overheat, in traffic, at high speeds?

If it is intermittent, your car is not 10 years old, if the thermostat is original it may be worn to the point of binding, and they can bind closed or partially open driving up the temp. At this age, your radiator/tank cap could be blowing off pressure and needs replacing.   Do you have a good mechanic?  If he is honest and good, have them pressure test the cooling system, test the cap for rated pressure. 

Have you owned this car since it was new?  

Has the coolant been changed?   How many miles on the car? Has the water pump belt been changed?

Keep the coolant at the correct level about 2 inches below the top.

Do you smell coolant?


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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 just purchased the car. There are only 3 hoses on the coolant tank. One goes to the throttle body and then tees off to the radiator as well. One hose is just an over flow and the other hose goes down behind the engine I'm assuming to the heater core. The person I bought car from said the thermostat has been changed not sure about flush though. I pulled the hose that's goes from the throttle body to the coolant tank started car I did not have a constant flow but I had coolant shoot out like every 10-20 seconds. If I turn ac on car will overheat right away. If I drive like 55-60 mph car runs fine. Get to 70-75 needle starts creeping up can probably go 10 miles at that speed before I would need to shut it down. There is no coolant in the oil or oil in the coolant and no white smoke out back. 

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Since you are overheating intermittently, it sounds like your purge line may be partially clogged, you should get a steady stream.  you do not appear to be getting a steady stream.

If the stat was replaced, it is possible that in the lead up to the stat being changed that someone put sealer into the tank.  that can clog the purge line

I do not know the 06 well enough to give you definitive instructions but there are people here that should be able to give you specific photos and advice. 

But generally, you need to tract that hose over to the throttle body and detach that hose. You will notice a small hole, DO NOT snake it out.   That hose should be attached to a nipple that can be screwed out, screw it out with a 15mm wrench (15mm is a guess) or deep socket and remove it, clean out that small hole with a pipe cleaner.

Hope this helps, others will reply here with photos if they are available to help you and us visualize this. 

Make sure your coolant is 50/50 and that your cap is good


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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 pulled the purge hose off the throttle body unbolted the nipple and took it off. It wasn't blocked. I did notice alot of belt dust though so I took main drive belt off and the tensioner off. The tension had rib marks from the belt wore into it so I ordered a new belt and tensioner pulley. Changed the alternator belt out as well since I was in there. The new parts will be here in the morning so when I get them put on and see what happens if it still overheats I'll take it to a mechanic I trust and see what is going on. I'm pretty sure it's not the headgasket but who knows.

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Water pump belt?

If the water pump belt was that bad I think you found your problem.

Check to see if your coolant is low.  I dont like that your air purge line was not a steady flow.

I doubt that its head gaskets.  But you can do a quick test.  Buy the Balkamp block tester from Napa.  They will need to order it or you can buy it on line. Easy test, you will know in 10 min if head gasket is bad.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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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Will do and thanks alot I appreciate your help and yes was the water pump belt.

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10 minutes ago, dgladillac said:

Will do and thanks alot I appreciate your help and yes was the water pump belt.

Thats really good news and probably the source of your overheating.

And guess what, the slipping belt may be the cause of the slow stream from the purge line!!! 

The overheating at highway speeds is also a clue to a bad water pump belt.

Post photos of the tensioner and belt.  Upload to photobucket and link them here. 

Let us know!


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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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Well got home from work and new tensioner and belt were here. Took pics of the way old belt was routed and it was wrong got a diagram of the right way to route the belt went on about a 60 mile trip needle never went past half way. Thanks for all your help body by fisher. 

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1 hour ago, dgladillac said:

Well got home from work and new tensioner and belt were here. Took pics of the way old belt was routed and it was wrong got a diagram of the right way to route the belt went on about a 60 mile trip needle never went past half way. Thanks for all your help body by fisher. 

It was good working with you!  Very happy you solved the problem, sharing your experience makes us better.  If we can help come on back. 

Do me a favor when you get a chance and have nothing else to do.......now that you fixed your water pump belt, you are getting full flow.   Test your purge line again, and see how the flow is now.... it will be a lesson learned for us.    Let me know, how your flow is, :D


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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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