We just purchased a junked engine and installed it into our 92 Legacy non-Turbo. This was an engine purchased from an engine dealer. Supposedly checked out, cleaned, etc.

 

The engine idles really rough, but after about 1000 rpm, it's smooth as silk. We just ran a compression test and got 150,150 on the driver side and 90,100 on the passenger side. With oil in the 2 low cylinders, the numbers did not change.

 

1) Are these numbers significant enough for the engine to idle poorly?

 

2) Should we contact the engine dealer about this? The specs call for no more than 20% differential.

 

Thanks,

Sam

those sides seem low, that would effect drivability some. did you check the timing belt tensioner and the belt? maybe that side is lined up slightly off?

did you test both sides the same, intake propped open and all the spark plugs out? starter turns the motor over smoothly?

 

can you do a leak down test to see where (if) you're loosing it?

 

i would call the company now and see what their policy is so you know how long you have to diagnose the problem.

If oil didn't help the numbers, then I'd say either the valves are leaking, or the headgasket is blown...or possibly both.

 

I would probably lean towards the headgasket. It would cause idle/drivability issues. Definitely contact the dealer.