GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi Im David, yes possible air in the system, possible intermittent temp sensor or temp sensor wiring
heres a couple prints
you didnt say it was losing heat in the cab. and if it was a head gasket, you would be overheating and not fluctuating. were the thermostats replaced due to this issue or was it due to something else?
so basically you have a temp gauge that has no ides where its at. make sure the system is full of coolant, bleed the air out of it if any, then while someone is inside the cab do a wiggle test on the wiring to the temp sensor to see if it jumps around.
usually the coolant temp sensor affects all kinds of inputs and outputs to the computer to compensate for different readings whether its climate control or mass airflow and a few others, so yes, indirectly it will affect it.
and on some vehicles, theres no affect at all.
not good. overheating?
you sure you installed the t stats correctly?
like at the cold mark?
did you put the t stat in backwards?
i gotta get home. catch you in an hour
87??? WOW. take the temp sensor out and put aa heat gun to it. see what the gauge does.
any news? update?
checking in to see how its going
do you still need assistance or not????????????
how did you determine that? block test?
i disagree. your temp would be rising.
white exhaust smoke?, coolant in oil? rising temps?
do a compression test. or a cylinder leak down
ill opt out cause we aint seeing eye to eye on this so take it to your diesel guy. lets just agree to disagree my friend. good luck to you.
Hi my name is***** you still requiring assistance?
I can try. The truck doesn't come to operating temperature and no heat?
If the radiator was replaced for a cooling system concern, or replaced during a front end body shop repair, it may be missing the radiator surge tank restriction orifice. Remove the surge tank hose from the radiator and visually inspect the radiator tank nipple that feeds the surge tank. If the radiator is missing the surge tank restriction orifice there will be an increased amount of coolant flow to the surge tank. Excessive coolant flow may induce DTC P0128.
If the radiator surge tank restriction is missing, the radiator needs to be replaced with the proper replacement radiator.
Okay. And did you replace the thermostat for this issue? Or has this happened after the fact?
Okay let me do some digging and I will get back with you in a moment!
The truck needs head gaskets. You can confirm with a block test and let it run for an hour to an hour and a half. Sorry to be the barer of bad news!
I have a feeling this may be in the early stages. You may need to run the hydrocarbon test again. If that doesn't show anything an extended block test (1 - 1.5 hrs) will show exhaust gases in the cooling system. Is there anything else I can help you with?