I never got a P0128 like I did when I first replaced the thermostat. The engine just overheats. I have plenty of DexCool in the system and haven't had any leaks. Just wondering if anyone has any ideas before I change out the thermostat again even though I just did it 4 months ago? Thanks for your time. 2005 Envoy XL ~160K miles.
Engine Overheating with replaced 4 month old Thermostat
- Thread starter dwieg
- Start date
I'd be very suspicious of the thermostat as well. What brand did you put in? I assume it worked fine after replacement until recently? Hoses look good and don't feel soft? You didn't add anything that could have congealed up in the radiator passages? Any debris caught in the fins external to the radiator that could impede airflow?
Other things it might be...
Water pump - is it pushing coolant like it should?
Radiator blockage - I had that happen to my old car, previous guy had dumped who knows what random stuff in for coolant and it turned into sludge and plugged up part of the radiator. Got it flushed and all was good again.
Water pump - is it pushing coolant like it should?
Radiator blockage - I had that happen to my old car, previous guy had dumped who knows what random stuff in for coolant and it turned into sludge and plugged up part of the radiator. Got it flushed and all was good again.
This won't help you any but, the P0128 shows up for coolant below operating temperature. (ie. Thermostat stuck open.) I'm not sure if there's an overheat code but I doubt it.
Does it overheat all the time or just certain situations? Have you checked the operation of the fan? Using a rag or gloved hand, if you can stop the fan easily like in this video, the clutch is toast.
https://www.youtube.com/watch?v=N9KJ3XH84FY
https://www.youtube.com/watch?v=N9KJ3XH84FY
Mine also rises in hot weather and AC on, but my clutch isn't easy to stop... there was this one occasion a few months back, temps in the mid 90s, after climbing a long hill, temp began rising, popped the hood and fan was barely moving....hasn't done it since...Sparky said:
Truly appreciate this website and you all helping. I went ahead and replaced the Thermostat that was only 4 months old, but I checked the one I took out in boiling water and it seemed to open just fine. So I put it all back together and filled the system up with coolant. I get to the almost full point and I hear dripping. Well since 4 months ago when I changed the Thermostat, I also had to change the Heater Control Valve, I knew this sound and where it was coming from. So I took off the wiper fluid container, moved the overflow, and noticed the sieve that was my hoses connected to the control valve. So I took this off again, mind you it is only 4 months old, upon removal, the hoses broke apart the valve stems. This was without manhandling it, the stems were very brittle. To take a step back, I noticed when I took the thermostat off, very little coolant drained out. This told me I have a leak somewhere and that is most likely the reason for the overheating. So now I am going to replace this valve once again, this time, I am going to attempt to replace the hoses that connect to it. Hopefully this will solve all of my problems. Of course since the engine overheated once, I have to do an oil change since my oil is toast. The Envoy XL just turned to 149K miles, so I am expecting to start repairing things, just not repairing the same thing twice in 4 months. Next project after this is to replace the fuel pump, because of course when I received my letter on my recall of the sender, I was passed the mileage accepted. So I am not looking forward to that job, but it will be done. Thanks again.
Similar problem for me. Overheating. New T-stat, water pump. A/C never got warm. Just got a coolant temperature sensor, but where is it? Lots of different locations found on line.Right block behind alternator, left block above t stat. Sure could use a little help with the how to and the where it's at. Maybe a video specific to my 02 TB inline 6, please....