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Chris (aka-Moose)
Chris (aka-Moose), GMC Technician
Category: GMC
Satisfied Customers: 46905
Experience:  16 years of experience
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GMC Sierra HD: 2008 GMC Duramax 6.6L Allison Transmission,

Customer Question

2008 GMC Duramax 6.6L Allison Transmission, 110,000 mi.
Temperature gauge always runs at 210 degrees even on flat land pulling nothing. Two years ago when I traveled to WY pulling my travel trailer (approx. 8500 lbs) I had started loosing power. The temp. raised up to 230 and the oil pressure was dropping. I had the truck serviced by GM mechanics and they said the radiator was plugged. The radiator was cleaned and flushed. Although it helped some on the long grades the only way I could keep the temp and pressure regulated to turn off the AC and run at 40 MPH. I would think this truck should pull this weight easily. What should I check or fix to alleviate this problem?
Submitted: 1 year ago.
Category: GMC
Expert:  Chris (aka-Moose) replied 1 year ago.
Hello, I'm Chris. Thanks for seeking us for help.
Have you checked for a sticking thermostat, fan issue, or air getting packed into the cooling system from a head gasket issue? If the radiator was clogged and that helped some that can equally mean there is likely gunk and corrosion buildup inside the engine, have you tried flushing the engine with chemicals?
You want a excellent 5 star answer & I would like to be rated the same for providing it. Consider I don't know your skill level & I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies. Try your best to respond with good detail so I can do the same. I normally log in at 3pm and work late. A rating is required. Your rating me, what I type. I am not an employee of this website, nor have control over the fees or the time it took to get a response. If you rate negative or not at all you still paid, but I get nothing. I want you pleased with me and my efforts, so let me know if your experience here has come up short.
Thanks Chris