98 2.5 Overheat

[sprite]

Seasons Greetings,

This is a continuation note from an earlier thread, "98 overheating" from 12/13/05.

With symtoms of the "head gasket problem," the Subaru service dept. determined that my Forester had a cracked cylinder sleeve. The diagnostic procedures performed were a compression test (one faulty cylinder) and a cooling system pressure test (no external leaks). Can one tell the difference between a cylinder problem and a head gasket problem without removing the head? Curious...

Thanks for any comments, Sprite.

[Setright]

Well, no.

 

However, the cylinder liners are of the "dry" type. They're pressed into the alu block and have no contact with the coolant.

 

The most likely thing is a tiny head gasket leak. Compression and exhaust gases are slipping out, into the coolant, but the leak is too small to register on a comp test.

 

Try testing the coolant for carbon monoxide. A cracked cylinder liner AND a cracked block would give the same symptoms as a HG failure, but it's not very likely.

[nipper]

Seasons Greetings,

This is a continuation note from an earlier thread, "98 overheating" from 12/13/05.

With symtoms of the "head gasket problem," the Subaru service dept. determined that my Forester had a cracked cylinder sleeve. The diagnostic procedures performed were a compression test (one faulty cylinder) and a cooling system pressure test (no external leaks). Can one tell the difference between a cylinder problem and a head gasket problem without removing the head? Curious...

Thanks for any comments, Sprite.

 

Yes you do a wet dry compression test. if both numbers are the same you rule out the valves and rings. If the liner is cracked, i would imagine the rings would get damaged and allow compression leakage

Now when the car overheated, how BADLY did it over heat. It is possible to damage the liners, but you really need to cook the engine, and usually a rod bearing would go too making alot of noise.

They really need to do a exhaust gas test at the rediator. Leaks can be directional at times, and what may not show up in a pressure test (14-18 psi) would sure as hell show up while the car was running (12-15,000 psi) combustion pressure.

 

nipper

[sprite]

I can drive the car around town (short trips, less than 20 miles) with the temp gauge normal. The car runs and sounds normal, although, oil consumption is apparent (ending up in my radiator). It mostly sits until I decide on a course of action.

 

Cheers

[nipper]

oil in the radiator .... thats a headgasket. story over

 

 

 

nipper