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GM Tech (Cam)
GM Tech (Cam), Auto Service Tech
Category: Car
Satisfied Customers: 29518
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2004 silverado 2500: heats..our 5th wheel..water pump went..fine till

Resolved Question:

I have a 2004 Silverado 2500HD diesel that over heats whenever we tow our 5th wheel up hill. It started when the water pump went after we headed west out of Denver. It was fine till we started going up hill near Price Utah and had to be towed. They have tried 2 sets of therermostats, 2 coolant flushes, replaced the water pump which was leaking and a new fan clutch. Now it runs hot even when I'm not towing. Also when it over heated it was down 2 gallons but did not see antifreeze on ground or in the oil. Any suggestions?

Submitted: 6 years ago.
Category: Car
Expert:  GM Tech (Cam) replied 6 years ago.
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GM Tech (Cam) :

I will do my best to assist you. When you are finished please click on accept only if you are satisified. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can.

GM Tech (Cam) :

What is the 8th digit of your VIN?

Expert:  GM Tech (Cam) replied 6 years ago.
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If you are still working with your Expert on this question, you can post additional replies and receive additional information on this page.  If you received a satisfactory answer in Chat, you can accept the chat conversation above.
Expert:  GM Tech (Cam) replied 6 years ago.

What is the 8th digit of the VIN please.


Customer: replied 6 years ago.
The 8th digit on the vehicle's VIN is 2
Expert:  GM Tech (Cam) replied 6 years ago.

Ok, does it fully overheat or does it push more coolant out than anything?


Customer: replied 6 years ago.
It fully over-heats. Bells ring and the insturment panel flashes "engine overheat"
Expert:  GM Tech (Cam) replied 6 years ago.

Ok, Does the engine coolant pressurize very quickly?

Customer: replied 6 years ago.

Don't know. do you want me to go start the truck and time it?

Expert:  GM Tech (Cam) replied 6 years ago.
Yes, please start it and see if the rad hose gets hard quickly. If not, rev the engine a few times and see if that does.
Customer: replied 6 years ago.
Let the engine run about 10 minutes and the temp only went up to 180 and the hoses never did feel hot or hard. Reved it up and held at 1800 rpm no change.
Expert:  GM Tech (Cam) replied 6 years ago.

OK, is the check engine light on?


Customer: replied 6 years ago.
Expert:  GM Tech (Cam) replied 6 years ago.

Ok, I suspect that there is either some debris between the rad and the charge air cooler or the head gaskets are leaking.


Customer: replied 6 years ago.
Will compression test reveal either or both of these possibilities?
Expert:  GM Tech (Cam) replied 6 years ago.

Usually not. THe compression or even the block test usually do not. However if it always pushes the coolant out of the tank and hose, and you have changed the thermostats and pump, then that is all that is left.


Customer: replied 6 years ago.

There is a GM Service Bulletin dated August 2006 that I think refers to this question. Bulletin # XXXXX XXXXX Do you have an opinion on this as a possible resolution to the problem we are encountering?


The truck goes back to the shop tomorrow. Anything (other than the previous conversation) we should ask/share with the technician?

Expert:  GM Tech (Cam) replied 6 years ago.

IF it was only towing, then maybe, but since it overheats without towing I would say no. Possible that it was the cause and the overheating caused head gasket issues.


Customer: replied 6 years ago.
thanks for your insight and expertise..
Expert:  GM Tech (Cam) replied 6 years ago.

My pleasure. You can reply at any time for follow up information regarding this issue, even after you accept my answer and I will reply.




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