2003 subaru legacy- loosing coolant and apparent overheating. How do I check for a blown head gasket or other related problem. No coolant leaks on the floor in garage. After trip to town,20 miles total, hot smell and obvious heat coming from engine . Gauge showing average temp. Detail shop tells me that blisters on hood are from heat build-up. I`m at a loss.

if there are no leaks then they have problems with head gaskets blowing compression into coolant when cold remove rad cap fill with coolant run engine then rev up engine look for bubbles in coolant if so then replace head gaskets

Does it hold pressure? If not, first check pressure cap. If it's good, you may have a internal engine leak. Have some perform a pressure check on the system.

This vehicle is known for faulty headgasket (bad design).

If it is blown, coolant will seep into the cylinders and be burned off with the gas. You could also have a cracked head - in essence creating the same problem.
Check the compression of each cylinder to see.

Also a good indicator is oil in the overflow reservoir - and smoking tailpipe on startup (white smoke) - also increased temp as you have indicated - as the exhaust is leaking back into the coolant as well.

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Are you loosing Coolant? That and if there is a chocolate color in the oil are your best indication of a blown head gasket. Usually it will force coolant from the overflow tank under acceleration if the head gasket is going bad. There are a few different things that can make it surge, Fuel delivery, timing, vacuum leak. Takes more looking to find real reason for problem. Good luck and have a good day.

Change your thermostate also because this could be the cause of why it is overheating. it is not unusual for thermostates to go out. and it will only coast you around 10 usd to replace if you do it your self. and also check to see if your engine fans are working you can do this by starting the car and turning on the air conditioning. when you turn on the a/c the fans should run. hope this helps you out
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Aaron

Sounds like a small leak at head gasket or Water pump going. Small leak on head gasket under idle will leak slow, But when under load will leak faster. Have a compresion check done on the cylinder to locate. Also you might want to try a presure test on the coolant system. Good luck and hope this helps to get you going again.

A blown headgasket, needs replacing.

I hate to tell you this but the guy isn't returning your calls because the head gasket is blown and he probably knew it.
As for the 1990... have you checked the water pump for leaks? (front/ driver's side on the bottom of the engine) My guess is that it's faulty and unfortunately, it's behind the timing belt.
Both of these repairs will be a pretty penny.
Good luck!

The 97-99 2.5L DOHC Subaru engines were notorious for this problem, blown head gasket is very likely the cause. It is possible to test for the presence of exhaust gas in the coolant to verify. The reason the car seems to be overheating then cools down quickly when shut off is that the hot exhaust gas displaces the coolant at the top of the engine where the sensor is. If it happens consistently you will need to deal with it, I have worked on an engine that was run many miles under this condition and it damaged the block beyond repair. If you are a decent shade-tree mechanic, it is possible to do the work with the engine still in the car, you will have to raise it up an inch or two to get sufficient access. I have personally done 3 engines with this problem, a 98 and 2 99's.

Two possiblities; a blown head gasket, or a freeze plug leaking. If possible take it to a trusted shop and have the pressure checked on the radiator, they can tell you if your radiator is stopped up, or the freeze plug is leaking, and if it's blowing back in the radiator when you remove the cap then it's a blown head gasket.