Head gasket replacement on 90 legacy

[Brutewrench]

Hi all,

 

I am reaching the conclusion that there is something off on one side of the engine in my 90 Legacy. The car has slightly lower compression on the passenger pair of cylinders (125-130 psi vs 155-160 psi for the drivers side - all with throttle closed), it idles poorly, pulling plug wires has a greater effect on the drivers side. The car has also overheated before, as both the radiator and the thermostat are bad.

 

So my questions are -

1. If there is a weak head gasket, is there any predictable way to guess how long it will last? Other than the rough idling, the car runs OK.

2. Should there be any other symptoms with an impending failure? At the moment, both water and oil are clean.

3. Does the engine need to be pulled to pull the head? It looks pretty straightforward, but I have not disassembled a Subaru engine in over 10 years.

 

Thanks,

 

Gary

[jimmyberka]

In response to question #3, I just pulled the heads (without breaking them down) on my '90 Legacy wagon without taking out the engine. It is a very tight squeeze, and you have to jack the engine up and down as you fiddle with the long head bolts in order to get them to clear the holes in the block without hitting the frame and fender wells on the other end.

It was actually easier to put them back in.

I also did it without removing the intake manifold. You just have to be careful to slide the manifold gasket in as you are putting the heads back on and get the manifold bolts started before you touque down the heads.

[Brutewrench]

Thanks for the reply. How long did it take you to pull the head?

[jimmyberka]

I didn't really keep track of the time. It probably took at least 6 hours to take them off since you need to remove the radiator, timing covers and belt, drop the exhaust manifold etc.

If you go through with it, you ought to at least test the flow thru the radiator and get it fixed if its not up to par. Also, water pumps seem to go at around 100,000 miles and would be easy to change at this time.

Hopefully you can get some good info. on your Questions # 1 & 2 before you proceed. I don't think a small head gasket leak would show up in a compression test. You may have something more serious going on with your valves or the lower half of your engine. Good luck.

[THAWA]

For the record you dont have to raise the engine to remove the heads. I didnt have to and the came out fine. Just real tight :\

[jimmyberka]

If you did it on a '90 wagon 2.2 without raising the engine or taking anything off the head assembly, I am triuely amazed.

[Brutewrench]

Thanks for all the replies. I think I'm actually going to leave the car be for now. The more I drive the car, the better it runs. Since it sat most of the fall and winter, I think I will give it some good running time before messing with it.

 

It sounds like the heads can come off in place if you just leave the bolts in the head instead of trying to remove them completely from the head.

 

Thanks,

 

Gary

[rallynutdon]

IMHO and experence, that difference in compression wouldn't have me worried or doing anything if it still runs good. If it drops below 100 I'd start to think about doing something. BTW, how did you take the compression reading? Hot, cold, both dry and after squirting oil in the cylinders, plugs all out, throttle wide open? Also, I've done heads w/o jacking the engine.

[Brutewrench]

I did the compression test cold, since that was when the engine ran the worse. All the plugs were out. The throttle was closed - I read that the test should be done throttle open after the fact. I did not squirt oil in to see a response.

 

From my past experience with Corvairs, I concur with your assessment on low compression. I have not seem significant issues until the compression dips at least below 100 PSI.

 

I also tried adjusting the large needle screw on the air intake after i removed and cleaned the air intake. This adjustement seemed to smooth out the idle a little, but it may have been mu imagination - Im not sure how to properly adjust it. I can see that it regulates the amount of air that bypasses the throttle plate, so its impact is primarily on idle.

[THAWA]

If you did it on a '90 wagon 2.2 without raising the engine or taking anything off the head assembly, I am triuely amazed.

close, it was a sedan. I dunno what other stuff you had to remove from the head, do you mean the valve covers and stuff, or are you talking cam sprockets and manifold and stuff?

 

Also brute I dont think it's possible to remove all the bolts or any for that matter without removing the head. As for that screw, it's not supposed to be adjusted. You should try and put it back to where it was set from the factory, should have some paint on it to line it back up.

[Brutewrench]

Unfortunately, the paint was long gone on the screw. I did scribe its position as found and returned it to close to that position. Interestingly, I just picked up a 93 legacy and noticed that the screw was obsoleted somewhere between 90 and 93.