VIN: 4S3BK4957T8932954 1996 SUBARU LEGACY POSTAL ENG: 2.2 SFI 170,000 + miles OK! I use my Subaru to deliver mail, and yes there is a postal model. I have two error codes PO325 (knock sensor 1 circuit malfunction and PO302 #2 cylinder misfire. Parts changed: COIL PLUGS PLUG WIRES Today I stopped by my shade tree mechanics and check compression on the #2 cylinder and it is reading 85 PSI. (had to pick my son up from school so did not have time to test the rest.) When he squirted oil into the plug hole the pressure increased to 120 PSI. I am told this means the piston rings are worn. My questions: Are the piston rings worn and if so is there a remedy without big maintenance? Can I continue to drive the car without doing more damage?
Are you burning oil? What color is the exhaust?
85 is definitely on the low side of a compression reading. It varies engine to tengine, but normal compression readings are around 140-180. The oil test does imply it is the rings not sealing, but there’s a chance it is the valves too. I doubt there would be any additional damage risk to the engine by driving, but you’ll probably continue to experience performance problems. There isn’t any simple fix, but folks are known to put in oil additives to try to string a worn engine along for a while until some better remedy is possible, like a replacement engine or rebuild or new car. It sounds like your mechanic knows what he/she is talking about.
It does sound like a ring problem and if this is caused by a stuck ring, or rings, you could try an additive such as SeaFoam or Berryman B-12 in the engine oil. The odds of this curing anything are extremely slim but it’s worth a shot at this point.
Rings would mean major engine work at great expense; assuming it’s even repairable once torn down. The cost of even a simple top end job (meaning rings and valve work) with no surprises would exceed the value of the car.
Are the valves adjustable on this engine?
I agree with the rings. There really is no solution in a bottle. The engine would need to be removed and rebuilt. With this age and miles, I’d drive it until it breaks, and keep doing basic maintenance until it does, but nothing expensive. Start putting money away now for the nect replacement. This car can still work for a year or two with a steady diet of oil changes and plug replacements, but will eventually drop another cylinder and become undriveable.
Compression test should really be done with all the plugs removed. Is it using oil? That is, according to my subie mechanic the best engine that they ever built. I have 237K on my 97, but not stop and go.If it is not smoking you aren’t hurting it any further.