My car is a MR2 Toyota 1987, the car right now keeps overheating, there is plenty of coolant in the radiator. I have a pretty good idea that it is the thermal state but I am not sure so that is why I am asking here. What usually happens is after driving the car for about 5 mins the temp gauge goes up to the halfway mark and if I turn on my heat, only cold air comes out. I am going to take out the thermal state either tommorrow or on friday it all depends on what day I get a jack. I will prob test the thermal by putting it in hot water and see if it good or not and then go from there. any advice or suggestions are welcome. thanks
Take a look at this thread:
Replacing the thermostat may solve your problem, but if it doesn’t, you may need a radiator cleaning, or replacement.
You might get fewer blank looks at the auto parts counter if you call it a thermostat instead of a thermal state.
So that is how you spell it! thanks for the correction
Welcome to the SDMB FireHazard!
It could be the thermostat, or it could be other problems. Depending on just how the heater is plumbed on your MR2 with a thermostat stuck closed (car overheats in 5 minutes after start) you could have hot air, or cold air from the heater.
Or you could have two problems
- Car overheats
- No heat from heater
Possible causes:
for #1 (In no particular order)
Thermostat stuck closed
Water pump failed (impeller has either corroded away or has fallen off the shaft) (Yes I have seen impellers fall of shaft :eek: )
air lock in engine
Blockage in either coolant passages in engine or hose
engine issues A blown head gasket is possible, or bad timing, a few other things.
For #2
heater control valve failed closed
heater core completely plugged (yes it happens)
thermostat stuck closed (but even then I would expect some heat, but it is possible if the car is plumbed a particular way that a no heat condition could be caused by a bad T-stat
blockage in another hose
Air lock in heater core.
About air locks. Some cars will not get all the air out of the system just by pouring coolant into the resivour tank. These engines will hold an air bubble in somewhere in the engine, and may not allow circulation of the coolant due to the air bubble. This can cause an overheat, no heat from heater, and engine failure. Air locks can be a pain in the ass to get out. Technicians now a days use a device that pulls a vacuum in the cooling system, and then they let the vacuum suck the coolant into the engine.
doing this at home would be much more difficult.
You would have to try and find the heater hoses, and remove them 1 at a time and try to get the air bubble out.
MR2 are mid engined cars, and not the most fun car ever built to work on. If a thermostat does not fix your problem you might consider shipping it over to a good shop to check out and repair.
The more I think about it the more likely it seems that an air bubble might be the problem. I am not 100% certain, but this is probably where I would start to look.
Do not drive the car if it is overheating! Severe (and expensive) engine damage can occur very quickly.
Maybe Gary T will stop by and give you the benefit of his experience.
Sweet, thanks for the advice and the welcome Rick, I will go ahead and take the thermostat out and test it to see if that is the prob, if not then I will take the car to the shop and have them chck it out. thanks again
I’m a little confused by the description of symptoms. On most cars, the halfway mark on the temp gauge is normal, not an indicator of overheating. Does the gauge go on to indicate running hot?
No heat from the radiator is a classic symptom of a low coolant level. There are other things that can cause it, but the other classic symptom of low coolant level is overheating, so that’s the first thing to investigate.
You say there is plenty of coolant in the radiator. Let’s start there. Did you actually remove the pressure cap (cold engine only !) and see that the level was up to the brim? If you checked the level in the reservoir, you don’t know what is in the radiator and engine. Reservoir level is not a reliable indicator of the level of coolant in the system.
If it was the reservoir you checked, the next step is to check the level in the engine and radiator and top up as necessary. If I recall correctly, the pressure cap is in the engine compartment while the radiator is up front behind the grill (but even though the cap isn’t actually on the radiator, it’s still called a radiator cap). There are likely one or more bleeder screws to let air out during filling, possibly on the radiator and on some pipe or housing high in the engine compartment. They need to be opened until liquid runs out, then closed.
If you checked at the cap, it’s still possible there’s an air lock in the system. Try bleeding as described above. A service manual outlining the proper fill procedure will be very helpful, maybe necessary.
There’s not much point in checking or replacing the thermostat or anything else until you KNOW FOR A FACT that the cooling system - not just the reservoir - is indeed full. Once it’s full, see how it does. If it no longer overheats and there’s heat from the heater, the remaing problem will be finding and fixing the leak that caused it to get low. If there are still problems, then it’s time for further investigation.