Originally Posted by butthead
my car overheated so i changed the thermostat and it stopped overheating but now the temputure gage on the dash constantly reads in the red so i replaced the cinder unit and its still reading in the red im out of ideas if you can think of something or have any suggestions please help thanks.
Yeah I think I will take up VWHOBO's old job of making sure that when the phrase "DUH" was needed, it was called out.
Hey Butthead (hmm appropriate?!) before you can expect any help with a vehicular problem, you must first understand that most real tech's actually prefer the car to be in their presence rather than online due to the complex nature of diagnosis and troubleshooting. With that now stated and known, I will expand that thought into the fact that when you ARE online explaining a problem expecting help, it is nice to explain any and everything involved in the equation starting off with things like what kind of vehicle we might be talking about like year,make, model, engine type and size, etc.
Now I will expand on what I do know about this problem......, you say that you replaced the thermostat. Other than the overheating, why do you think the thermostat was causing the problem? Did you do a heating system check by running the HVAC system in heater mode and were not getting any heat? The thermostat could most def. cause your problem, but I would never jump to conclusions before making sure that ALL factors point to it. If the thermostat was stuck shut, you'd not have any heat inside and she'd be prone to overheating. If it was stuck open, the engine would not reach optimal operating temp. and you'd still not have "much" heat inside.
Deductive reason process: If you replaced the thermostat and then engine did not everheat and you checked and you were getting plenty of heat from the heater inside, then it would seem you solved the problem with the thermostat. HOWEVER, you say that you also replaced the "cinder" unit because the gauge was reading red. What is that? Cinders come out of my chimney in the winter and from coal- powered locomotives. I guess you replaced the thermostatic coolant temperature sensor aka. "temp sending unit."
When your gauge now shows a temp in the red zone, are you really overheating? Does the car have a strange burning odor or is coolant in the recov. tank boiling? While this is going on does the heater blow hot air?
I fully support, at this time, that when you replaced the thermostat, you have gotten air into the line somewhere and on the side that the temp sensor is on, it is getting hot. All your info. points to this thus far. The second theory that Wally has about having a cracked/damaged head gasket superheating the coolant is not likely in this case! First off, if you had a bad head gasket, gases(compression) and liquids(coolant) typically flow both ways but not all the time. If you are lossing compression to the cooling system due to a bad head gasket, you will typically notice air bubbles in the coolant recov. tank due to air in the system and it is not from boiling. Boiling would be if it was overheating. When the engine was off you'd likely have coolant draining into the engine oil as well. you'd also likely be burning white smoke. All that depends on where the damage would be to the gasket and what I just said does not ALWAYS happen. I think your problem is far more simple than all this.
You need to do a more in-depth diagnosis and tell me answers to the questions that I have posed before I or anyone else can help you any more. You're now saying that it is NOT overheating yet the temp gauge runs in the red all the time. Bleed the system of air....I think you got air in it.