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Carhelp4u, ASE Certified Tech
Category: GM
Satisfied Customers: 5203
Experience:  ASE Certification
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how do i change the thermostats in a 2005 duramax diesel

Customer Question

how do i change the thermostats in a 2005 duramax diesel
Submitted: 7 years ago.
Category: GM
Expert:  Carhelp4u replied 7 years ago.
Have you already started this repair? If so what have you done at this point?
Customer: replied 7 years ago.
no I opened the hood. my problem is it has no heat, the temp gauge will go to 200 back to 180 will gete heat and low coolent warning will appear( has happened three times back to back. last time,short trip temp gauge never when up but coolent came out of the overflow of the tank
Expert:  Carhelp4u replied 7 years ago.
So you are saying without the engine temperature going up, the coolant overflowed from the coolant overflow container? Has this vehicle been using any antifreeze otherwise? How many miles are on this engine?
Customer: replied 7 years ago.

yes with out the temp gauge going up. but it was a short trip the truck has 80 k and has never used fluid

Expert:  Carhelp4u replied 7 years ago.
Well honestly my concern at this point would be where the pressure came to make the cooling system overflow while it was still cool. Now if the thermostats were not working and this vehicle was getting hot, I would say yes that this is a problem with one of the stats, but being the engine was cold really makes me wonder if this is more of a compression issue leaking into the cooling system. This is most commonly caused by a faulty head gasket, or a faulty cooling system pressure cap. You may want to remove the cap and allow for the engine to run up to operating temp. If there is a constant flow of air bubbles, this very well may be a head gasket issue. This would explain no heat within the vehicle if the heater core is getting filled with compression (air pockets). Keep in mind that a problem like this would likely be covered under a gm warranty. If you post the last 8 digits of your vin# XXXXX can verify this. If you do not note any air bubbles working throughout the cooling system, you may want to replace the cap, or test the cap with a pressure tester to verify that it is holding 15 psi or somewhere close to that point. Feel free to contact me with any questions, findings, or problems!
Customer: replied 7 years ago.
I have the truck running with the resevoir cap off and when I started the truck there was no fluid in the tank,should I put some fluid in the resevoir
Expert:  Carhelp4u replied 7 years ago.
Oh yes, you should have some coolant in there to see where the level goes.
Customer: replied 7 years ago.

I put a half gallon of fluid in the resevoir and I'm letting it run. ther ewere bubles entering the tank right away i am going out to check it again still bubbles with the cap off

VIN 1GTHK23275F866532

Expert:  Carhelp4u replied 7 years ago.

Ok first off, the engine warranty on this engine is good until 100,017 miles and the date of 12/06/09. This would be a $100 deductable repair though if needed. The coolnat coming from the overflow while still cold really concerns me as the pressure just should not have been there at that point. I would also recommend allowing for the engine to cool and then properly filling the cooling system to verify that there are no air pockets or anything of this nature. You stated there was no coolant in the container today and that could certainly mean that there is air within the cooling system. Here is how you should be filling this system.

  • Slowly fill the cooling system with a 50/50 coolant mixture.
  • Install the coolant pressure cap.
  • Start the engine.
  • Run the engine until the engine reaches normal operating temperature.
  • Allow the engine to idle for 3 minutes.
  • Shut the engine OFF.
  • Allow the engine to cool.
  • Top off the coolant as necessary.
  • Rinse away any excess coolant from the engine and the engine compartment.
  • Customer: replied 7 years ago.

    I checked truck after running 10 or so minutes and air was still bubbleing into tank. Top radiator hose was cold as well as the fluid returning to the resevoir. when I cut the engine off an amount of fluid came out of the tank. I will let the engine cool and follow you instructions on fillinn the system. How long does the engine need to run to move the temp gauge to normal operating temperture?

    Expert:  Carhelp4u replied 7 years ago.
    Normally you should see the temp up within 10 minutes or so, but you may want to bring the rpms up above idle. In other words, you may want to allow the engine to run at 1800rpms or so for a few minutes.
    Customer: replied 7 years ago.

    Do you think this is something I should call the dealer about in the morning. I let the engine run10 minutes at idle and another 7 minutes at 1500 rpm and the top radiater hose was still cold as well as the fluid in the resevoir. If the thermostats were not opening would this affect the temps of the top hose

    Expert:  Carhelp4u replied 7 years ago.
    Yes, but you would be seeing this engine getting hot rather than staying cold. As far as the coolant being expelled from the overflow, I have no idea why that would happen if the thermostats were not opening and the engine was staying cold. If you want, I can opt out so other experts can assist you. I just cannot say I have seen a case such as you are dealing with at this point.
    Customer: replied 7 years ago.
    What ever you feel I would like know what to do, if another tech has an answer I would like to hear it
    Expert:  Carhelp4u replied 7 years ago.
    Ok I will opt out and send a message to other online experts to see if they have any input on this problem. Thanks for your patience!
    Customer: replied 7 years ago.
    OK Thanks
    Expert:  Carhelp4u replied 7 years ago.
    We are still with you, I have emailed a few other experts, but they felt the same way I did. I am going to message some more to let others know your problem to see if anyone else has seen this before.
    Customer: replied 7 years ago.
    OK I will wait to hear from you