Normal Compression????

[mtnman]

I have a 97 OBW 2.5L w/ 164k mi. I recentlly had the engine rebuilt 2k mi ago. I just checked the comprssion in each cylinder and came up with:

#1: 180 PSI

#2: 180 PSI

#3: 165 PSI

#4: 180 PSI



So, what is the normal range and how bad is it that one is 8% off?



Also, I have a strong rattling sound when I first start the engine (cold). . . probably a rod bearing?.. . then goes away after two seconds. . . thoughts?



Are they related issues?

[Subhuman]

Cylinders 1,2 and 4 on my 97 get around 216 PSI and I was told by the dealer (Carter Subaru in Seattle) that, that PSI was normal and that Subarus run high like that. However my #3 was at 90 PSI. They said when #3 goes it's almost alway because of a burnt valve. Cylinder #3 has a lot connected to it and it's my understanding that it's usually the first to go if there is any cylinder trouble. I don't get the rattling you do but my 97 shakes because it's off balance and occasionally dies at stops.

[Subhuman]

I just thought a little more on your matter and remembered that the dealer told me that when a cylinder does that it can ruin your cats and break up the structure in it. That could be the cause of your noise.

[porcupine73]

The 180psi cylinders are good. I forget what the spec is for the maximum difference between cylinders, but 165psi is low.

Not sure about the rattle....if you bang on the bottom of the cats it should not sound like a box of rocks.

[mtnman]

So, to follow up. I was driving down I-5 when the rattling noise started increasing in volume. louder. louder. louder. I pulled over at the next exit only for my car to stall in the intersection and coast into a gas station. I checked the oil, which was normal. waited a few minutes and tried to turn to car on. nothing but a loud rattling sound, the car barley turned over and then died. I called a tow truck and had it taken back to the shop (TNA Quality Auto Repair) that did the original engine work.

Two and a half weeks later I have another rebuilt engine in my car. Turns out that I had a seized rod bearing. Hopefully the shop got their **** together when they worked on my car this time. Third times the charm, right?