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Subaru 2002 Legacy wagon overheating

I drive the car 35 minutes to and from work and never exceed 60mph. The car does not overheat. I drive it on the turnpike at 70-75mph and it overheats. I had the thermostat changed and it still is overheating. Today before I went to work I looked at the overflow recepticle and it was at the proper level. When I got to work it was about 2 inches from the top of the overflow recepticle. I had my mechanic check the coolant in order to find out if it was a head gasket. Negative. The car has 105,000 miles on it and I bought it at 91,000 miles. The dealer said that he had replaced the headgasket prior to me buying it. What’s my next move?

Define “overheats.” Does it boil over and push water out of the radiator, or does the gauge just read higher than normal? Is coolant being lost, and if so, how much?

Is the radiator full? Checking the overflow bottle isn’t enough. You have to check the radiator (cold), too.

Someone needs to measure the ACTUAL temperature of the coolant and determine whether or not it’s too hot. The gauge is ball-park at best.

Can the dealer PROVE he replaced the head gaskets? If not, I wouldn’t believe him.

Be aware that Subaru engines do not take kindly to overheating, so if there really is an overheating issue it must be addressed ASAP to prevent significant and expensive damage.

Prior to changing thermostat, it max out on the gauge. Now it doesn’t show on the gauge, but overflows out of the overflow bottle. If it was the head gasket wouldn’t it show signs of hydrocarbons in the coolant? I’ll check the radiator cold to see how much has been lost and check the temperature.

Note that you are also due to a timing belt change at 105K miles. I would get that done, water pump & tensioner replacement done at this time, too. This may or may not help with the overheating issue, but it is certainly time to make sure it gets done.

“Prior to changing thermostat, it max out on the gauge. Now it doesn’t show on the gauge, but overflows out of the overflow bottle.”

One of the things that you have to realize is that on many modern cars–Subaru included–the temperature gauge is really just a glorified idiot light. The term is a “buffered” temperature gauge, IIRC.

These modern (buffered) temp gauges have essentially 3 positions–cold, “normal”, and overheating. The problem with that design is that an engine that is consistently running hotter than normal–but not yet overheating–will show a “normal” temperature on the gauge.

So–I think that this engine is consistently running too hot when driven at high speed. Changing the thermostat was a good idea, but it was not the total solution to the problem. One thing that I would suggest you consider is a radiator that is so badly clogged that it cannot pass coolant fast enough. You may need to replace the radiator.

If it is not overheating on the gauge but pushing coolant out the overflow, I would replace the radiator cap first. I wouldn’t replace the timing belt until I got the coolant loss straightened out. If you have a damaged engine the timing belt replacement would be wasted.