just bought an 02 subaru forester sport pkg. It has 55K miles on it. It was really owned by a little old lady previously. It runs great BUT the engine gauge intermittently goes nuts and goes almost to the red/top end of the gauge. However, when I stop and check the engine, it and the radiator cap only seem to be warm. I have had the thermostadt replaced, but that does not solve the problem. The only variable that changes this is when I shut off the engine for 5 minutes or so. When I turn it back on, the gauge goes down by a quarter or more. Any insight on how to solve this problem?
There is always the possibility that your temperature sending unit is malfunctioning, and that the engine is not really overheating. A mechanic can check the actual operating temperature of the engine.
Hopefully a flukey temp sending unit is the problem, but don’t totally dismiss the idea of a possible breached head gasket since this engine is prone to that problem. For the time being, check the coolant for the presence of motor oil (a dark, greasy line at the top of the coolant overflow bottle is a good tip-off) and check the motor oil for the presence of coolant (it would look like a chocolate milkshake).
Incidentally, unless you can confirm with documentation that the timing belt has already been replaced, you need to do that immediately. The timing belt is supposed to be replaced at 8 years or 105k miles, whichever comes first. On the basis of elapsed time, this vital service is due. When an over-age belt snaps on this engine, just like on all “interference” engines, it will cause major internal engine damage that can cost ~$2,000 to repair, over and above the cost of the timing belt replacement.
The water pump, serpentine belt, and all belt tensioners should be replaced at the same time as the timing belt. And–who knows–maybe the possible overheating problem is related to a bad water pump. You might kill two birds with one stone by doing all of these jobs a.s.a.p.
I would visit a dealer and get a diagnosis. There is a 8yr/100,000 mile warranty on the head gaskets which could be a potential issue. Unfortunately many of these Subaru’s in this vintage had issue.
You are a due for a timing belt like VDC states. A headgasket out of pocket is $1000-$2000. You may want to get all information on this “little old lady” car before investing anything in it.