Coolant/Over heating problem

I have a 1998 Subaru Legacy Outback. It has about 250 000 km on it. Lately I have been having an issue with the coolant system - here is what has happened:

Jan 1 2010: Radiator leaking - I replaced the whole unit with a new one.

Feb 3 2010: Engine was miss firing and would not idle. I noticed a cable was hanging loose under the car. Once I secured the cable back into place - the car operated fine. I am not sure what this cable was - but it was located just in front of the front left tire, just beside the exhaust manifold, just aft of the radiator (perhaps the knock sensor?)

Feb 20: The temperature gauge went to high (after a long drive) - yet the engine was operating normaly, coolant levels normal, temperaure felt fine.

Feb 21: Went to the car in the morning, all the coolant in reserve tank was gone. Went to a mechanic and they could not find any leaks or any problems with the car - the temperature was back to normal.

March 3: Temperature went back to high (after a long drive). Took it to a mechanic and they replaced the temp. gauge.

March 10: Temperature shot up again (after about 60 km) and the mechanic played around with the new temperature gauge - have not had a problem with the temperature since.

March 14: Car started normally, but was surging during acceleration. I went under the car and noticed that the cable (that I referenced earlier) was about 1 mm loose - I pushed it back in and the car operated normally.

My question is: Why is my car continuously over heating? No mechanic nor I can seem to figure out what the problem is. Is there any relation to this sensor cable becoming loose and the enginer over heating? Any help would be greatly appreciated.

Have you put a thermostat in it? Can you get a picture of the wire that keeps coming loose?

Here is a link to 3 pictures of this sensor.
The mechanic just replaced the thermostat on the car not to long ago.

Here is the picture of the sensor - it is located again, just behind the radiator in front of the front left tire, beside the exhaust manifold and oil pan - these are pictures from under the car

http://picasaweb.google.com/Sean.in.India/Car?feat=directlink

thanks for the help

It is either a coolant temp sensor OR if it has a 3 prong plug in at the other end, it is a block heater. Usually the coolant temp sensor is on top of the engine though. As for it overheating, make sure the actual coolant temp sensor isn't reading incorrectly. If it isn't that, you might have a bad headgasket or two. They usually leak like a sieve as opposed to causing it to run bad.

Thanks,
I went to my mechanic and said it was my block heater - I guess it is just a coincidence that when I plugged it back in, my car worked better - it was so strange. I don't get it - but when I drove with it unplugged - nothing abnormal happened.
My mechanic says it is probably the head gasket - I will drive on it until it totally blows then perhaps put a new engine in

Good luck with that, a new engine is going to cost you a chunk of change if you can find one. The headgasket job is really easy with the exception of the right socket for the headbolts. It takes a 14mm 12 point socket. 3/8 drive is about the only thing I can ever get to fit into the space around the bolt and it takes a 1/2in bar to break em loose so its a bit of a challenge to get the tools together unless you have them already.

Yes, I think it can be a bad gasket too. Your coolent leak and overheating is intermittent.
When your mechanic had checked your car, does he put the coolent system under pressure while checking the pressure? Cause it's what he should do to find the leak. If he doesn't have this tool for that, change mechanics.

When it overheating, does your heater still working? Do you experience loss of power with your car?


PS: When I said bad gasket, it's not necessary the head gasket, it could be also the intake manifold gasket which is less important.

serge I love that windstar comment in your signature lol

serge i love that windstar comment in your signature lol

lol