I recently aquired a 92 Legacy with a 2.2 engine (130k miles). The compression on the 2 & 4 cylinders is 155, while 1 & 3 come in at 75 each. The engine passed a cylinder leak down test* administered by the Subaru shop after they installed a new timing belt. The old one was off by one notch. On restarting, the idle was rough. The owner suspended efforts at $400, figuring that Subarus would never able to get the car running smoothly again at a reasonable cost. She had it towed away for donation. The removed parts were placed in the trunk. I bought the car figuring, at worst, I could put the engine from my 91 into this car. I reinstalled the parts, and I have been driving it with a rough idle and lousy gas mileage (75 miles on a half tank). I would really like to see if I can solve this mystery. The car was towed into Subaru after a failed start on a -10 degree night. The owner "heard a clunk", and that was that. Before this episode, the car reportedly ran well and seemed to be well maintained. I interviewed the mechanic, and found that there were two siezed hydraulic lifters on the 1 & 3 side. I replaced these. So far, I have replaced the fuel, changed the oil and added one quart of Rizlone oil detergent. I've also changed the plugs. The 1 and 3 were carbon fouled, probably due to low compression. My reasoning tells me that there could be a fracture between the 1 and 3 cylinders. This would have to be low enough to allow at least a 50% buildup in compression and still pass the leakdown test. I could probably test for this by removing the rocker train (to close all the valves), moving the piston to the bottom-dead-center position and applying air. I don't know what this crack could look like because the block casting is probably sleeved. Then, the question: what to do about it, short of ditching the engine. As I think about this, I am not convinced that the "klunk" was the timing belt slipping. I've had timing belts that were off by a notch, and the car was still driveable. I would be interested in any other opinions. Thanks.
