Okay, today my heater stopped working, the car started overheating, and the engine does not idle at a constant RPM. The car revs up and down by itself while idling. The vents blow air but it is no longer warm/hot air. There is also some rattling at higher RPM, but thats minor, and may be unrelated.

What do you think is wrong? Would a vacuum leak cause this? Water pump timing belt set incorrectly? There are so many things that could go wrong, I wish I could better understand how a car works.

I had a power steering leak recently and drove around for about a month without power steering fluid. Just something to keep in mind. Maybe that fucked something up? I didn't fix the leak, and started using automatic transmission fluid instead of power steering fluid because it is cheaper.

I am getting a new car this winter but for the timebeing I need this thing to get me through exams. It is a 1992 Toyota Tercel - 300,000 km, I don't know if that is important information. I have a Haynes manual but it doesn't seem to be helping much.

Thanks, that makes sense.

The problem came back so I took out the thermostat with the housing. Thermostat doesn't seem to open in hot water. If I push down on the bottom of the therostat, is the top supposed to open? It's not opening. I didn't remove it from the housing because the washers didn't look great, although the thermostat looks fine.

One of the bolts keeping the thermostat housing in place snapped. I removed the bolt but now I need a new one. Also, I accidentally snapped one of the wire connectors. It is connected to the "Coolant Temperature Sending Unit". Maybe I can ducktape it or superglue it back together.

Thanks.

Yes, I can get a thermostat gasket, and thermostat O-ring with the thermostat. If I do replace it, I'll get those too.

As for the cable. It is the actual plastic part that connects the cable to the sensor that broke. On each side of the break there are two metal rails surrounded by plastic. I was just thinking of putting the glue on the plastic and taping it on the outside to keep the rails connected. Sorry, about the terminology, they look like rails, like on a power plug. I dont know what they are called.

Hehehe! I hope this is not a cooland leak though. Because in the Haynes manual it said once I remove the housing, coolant should spill, and it didn't. Although if the thermostat didn't open...

I ordered one anyways.

It says the thermostat is rated at 88 degrees celsius. I poured boiling water on it and it didn't open. How does that thing work anyways? Thermal expansion?

I should have probably checked if the hose from the radiator to the thermostat was cold.

Replacing the thermostat didn't do anything. I still have the same problem, the hose from the radiator to the engine is cold, and it overheats. Could it be because the bleed air valve is in the wrong position? I put it in the same position as my old thermostat, however in the manual it said it has to face up.

I had the same problem with my car, my thermostat wouldn't close nor open, causing the car to overheat etc. Put a new one in, Fixed!

Take a good look at the plumbing diagram in the Haynes book... then start prying up carpeting. You may very well have a leak, and it may very well be the heater core itself. If your vehicle is like mine, there's coolant present right up to the core inside the dashboard even when the heat is not turned on.

I had to bypass mine a while back...I had sort of smelled coolant, but attributed that to other problems which were causing overheating... lifted the carpet on the passenger side and- yikes!!

Not looking forward to replacing that core (the entire dash has to come apart). But I'd better do it soon...