Right some advise would be nice, car is a 95 wrx ra
I was giving it some beans yesterday and inadvertently hit the rev limiter when there was a bang and it started running rough.
pulled over as soon as i could oil pressure was normal and idle was fine so i drove on after a look under the bonnet, low revs it sounds like its missing a bit but it revs freely and higher revs 2.5k plus its just as normal.

Got home and checked the engine again and i'm getting smoke coming out of dipstick tube and filler neck, so expecting it to be ringland failure i did a compression test to determine which cylinder was at fault here are my results:

Cyl 1-171
Cyl 2-91
Cyl 3-168
Cyl 4-94

So did wet tests on cylinder 2 and 4 and seen little difference 100 and 94.

What else could cause both cylinders one the same side to be low?

 

Head gasket blown on the right side of the engine.

 

Both cylinders to oil ways?

 

Numbers should be between 142 to 171 psi with a 7% variation maximum between cyls is the factory spec.

 

Could be Head gasket blown across the 2 cylinders

 

Cylinder 1&3 left side and 3&4 right side.

 

Lol yea sorry bad day lol

 

Pressuring the crankcase would indicate pistons/rings but would expect a slightly higher 'wet' test result unless you have detted a couple of ringlands away.
What mileage has the engine done ? Would have a look at exhaust valve seats too while its apart.

Mick

 

Sorry for being a smart ****