My Impala has been in and out of the GM shop for the last three weeks trying to fix an overheating problem, not to the point of a boil over. Everything has been done including waterpump, tensioner, radiator, thermostat, hoses, flush heater core and finally removal of intakes and cleaning scale blockage in coolant ports and still no luck. In checking various components on the engine with a laser thermometer, I've found that the only hot area is around the thermostat LOWER housing where the temp sensor is at 235+. The upper thermo housing is normal at 190+ along with the radiator hoses, heater hoses and various other locations, wpump and engine areas. WTF!! is going on here?? Nobody including the shops GM engineer can diagnosis/fix the problem. The only thing that hasn't been checked is a combustion leak test which I think not the problem because of all areas except the lower thermosat housing shows normal temp. Thanks for any help here.
I measures temp with a laser thermometer and the system has been bled several times. It's had two new thermostats, one of which I gutted the internals and tried it and the only difference is it took longer to warm up but when it did the coolant area around the lower intake thermostat area still will run 235+. It has a new waterpump and the shop removed and verified it and supposed to of put a plastic gasket in place of the felt one. I don't know of a plastic one?? The fans are working properly as the shop forman took it up the hill with the laptop connected and verified the engine running hot. it has a new temp sensor also. Any ideas of where to go next would be appreciated.
They removed a freeze plug from the front of the block and checked that too!! Cannot believe still having this problem. i also had a new cat installed and I'm thinking that the resonator or muffler might be issue but don't know.
Have you checked for carbon monoxide in the coolant? CO in the coolant will be from cracked head or bad head gasket. Kind of a long shot but if you’re out of options… A exhaust gas analyzer can be used to check for CO at the radiator cap. Combustion gasses in the coolant will cause strange over heating problems.
Thats the only thing that hasn't been checked but according to a laser thermometer, the only hot area is around the lower thermostat housing where the sensor for the gauge is the rest of the motor, hoses etc run normal. Nobody at GM can understand why or what is causing the issue. Thanks again.
Another long shot...............
Did you buy the car used? Perhaps a shade tree mechanic replaced an intake manifold or head gasket and put it in top side down or used a wrong gasket, blocking a coolant passage.
We've had the car for four years and no head gasket repairs have been made. They did however repalce the upper intake and all gaskets upper and lower and cleaned the coolant ports that had some white crud blockage but still while going uphill or when ambient is 100+, the car wants to run hot never did before. Everyone is stumped?? Thanks
I have a similar issue, but I don't boil over.
I have been running about 1:00 or 2:00 on the temp gauge (about 220-230 I'm guessing), but then again, it's been in the low 100's here as of late.
I just put in a new 195 degree thermostat, temp sensor and radiator cap this weekend and that has helped some. I've been staying about 12:00 or just above or under.
I bled the system at the thermostat, but I might have a small air pocket still that I need to get to, probably have to flush the entire system again...
Keep us posted on your findings!
_________________ - 2001 Impala Base - Navy Blue Metallic
- 3800 Series II
RIP 10/23/2010, 191,197 miles - traded on a 2003 Tahoe Z71
My 01 started to heat up after several trips to the dealer for warranty work. It would heat up on the highway and cool down in traffic. Turned out to be an ignition switch! Dont ask me how why or what.... It was my moms car and it was and still has draw issues on the battery, so the dealer replaced the ing switch the pass lock system and some other things but never a BCM.
01 Impala LS- SS cluster, SS exhaust, SLP grille, GMPP handling sway bars, tubular trailing arms front and rear strut bars, KYB AGX struts and SSC Gen 2 springs, convertor delete pipe and some nice window tint....
88 Ranger- with a F/I 302 on 36" super swampers - "Rednecked"
73 Cutlass- with a 432 big block and a lot of go fast goodies
82 Cutlass- 350 weekend cruiser
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