14 replies to this topic

[Subarunation 713]

On my way to work yesterday all the sudden the CEL light starts flashing and the car (1999 Legacy L sedan 2.2 5 speed 220K miles) starts running light crap. I limp the car to work and once there try to check things out. Nothing really out of whack. I limp it home, about 35 miles, by just driving about 55 in 5th. CEL flashes, goes out, comes on, stays on, goes off, flashes again.

I did a search of some threads with compression in the title. Some were where the cylinder was low or a whole side was zero but none where only one cylinder was zero. btw- I mean ZERO! nothing, needle didn't even think about moving.
Cylinder #1- 165 psi
Cylinder #2- 170 psi
Cylinder #3- O psi
Cylinder #4- 172 psi

Plugs #1, #2 and #4 looked great. Plug #3 looked oily wet and sooty.

When running is sounds like there is an exhaust or intake leak but there is not. The exhaust pipe felt like putting my hand over the pipe of an old two cylinder John Deere. With zero compression my guess is when the piston goes down on intake it creates a vacuum and then when the exhaust valves open it is sucking in exhaust to equalize the pressure. But just a guess.

Before this it started easy, ran fine, used some oil but didn't miss. I was getting about 25 mpg down from my LONG term average of 27 mpg. Any thoughts?

[bstone]

Time to take the cylinder head off, send it for rebuilding and put down a new headgasket. Sorry.

[Fairtax4me]

Sounds like a burned valve. I bought my wagon with no compression on number 1.


About $50 in parts to fix it and it runs fine... for now.

[Subarunation 713]

Time to take the cylinder head off, send it for rebuilding and put down a new headgasket. Sorry.

From running smooth to this? No water in the oil no oil in the water all fluid levels OK. But even if the headgasket was completely shot I should still be able to get 15psi after cranking it 10+ times with wide open throttle don't you think?

It won't get a head gasket from me nor will I pull the head off. It will go in the front yard with a FOR SALE sign in the window. It still runs and drives and doesn't look too bad.

fairtax4me, thats probably what something in my #3 looks like. You had absolutely NO compression?

[Fairtax4me]

A Big ole fat Zero. Needle didn't even pretend to flinch when I cranked it. The other three cylinders were in the same ballpark as yours.

It's not that hard to just replace the valve. At 220k miles it's probably not worth putting much more into it than that. I'd say from start to finish it took me about 8 hours with a lot of screwing around. If you have or at least have access to a spring compressor you can do the job yourself in a day and have it back in good running shape for not much $$.

[Crazyeights]

Can you really just install one valve in a situation like this and get away with it for a while? Do you use a used one or new, lap it in or just hope? Pardon the questions but all these years I have just let the machine shop do it. I am always receptive to shortcuts when they work.

[Fairtax4me]

The whole repair was done as cheaply as I could possibly do it. The engine had no compression in cylinder one, and it had been driven for over 100 miles like that by the PO's son. For all I knew the rings were wiped out and there wold be low or no compression anyway, even after the repair.
I removed the head, removed the valve, then had to grind off a small piece of melted valve that had splattered itself to the valve seat. That took some time with a pick tool, then I used the old valve to grind the seat until it was smooth. After that I ground in the new valve, (brand new from Subaru) put the head back together and put it back on the engine. I did use a Subaru head gasket, because they had it in stock when I needed it and all the parts stores had to order it.
It fired up and ran on all four on the first crank. The lifters ticked like there was no tomorrow for about a half hour then quieted down.

I've got about 1,500 miles on it like that. Still waiting to see what goes wrong.

[Crazyeights]

1500 miles and still going, that's great! If anything fails now it will probably be another valve or something you didn't do. Time will tell.

[grossgary]

pretty sure the #3 cylinder exhaust valve is the one that usually burns too.

i wouldn't worry too much about just replacing one valve and calling it good. the others didn't reach their critical levels so likely to get plenty more miles out of them if they're properly adjusted this time.

[GeneralDisorder]

All the one's I've seen have been #4, but they have all been solid-lifter engines. Depending on the cause of the burned valve..... if it's lean injector related then #3 makes more sense because it's the last injector and the most likely to be lean (or more lean than the other's). If the valve lash has closed up and the valve hung open then it could technically happen on any cylinder. Both of the one's I have seen have been #4 exhaust valves though.

A leak-down check will show immediately where the loss of compression is going. Put the cylinder at TDC on the comp. stroke and run compressed air into the cylinder - if it's all escaping from the exhaust then you know where your problem lies..... or just pull the head since it really doesn't matter what is wrong - it has to come apart anyway.

GD

[General chaos]

a leak down test could show where the compression is going to.

to preform a leak down test you remove the spark plug. put an adpater into the spark plug thread. and hook up air to the adapter. make sure the valves are all closed on that cylinder. then where ever the air escapes from while airing up the cylinder. is where the problem is at.

[GeneralDisorder]

a leak down test could show where the compression is going to.

to preform a leak down test you remove the spark plug. put an adpater into the spark plug thread. and hook up air to the adapter. make sure the valves are all closed on that cylinder. then where ever the air escapes from while airing up the cylinder. is where the problem is at.

Echo? I just said that

GD

[Subarunation 713]

Follow up on my no compression issue.

Last Sunday I had to leave for work for the majority of the week. Before I left I thought, "what the heck" and poured some of my home brewed penetrating oil (50% acetone/50% ATF) in the cylinder and left it sit.

When I got back i left the spark plug out and turned it over to clear the fluid (didn't want hydro lock). I put the spark plug back in and fired it up. SMOKE, holy COW did it SMOKE! Like Seafoam cubed smoke. I left it run until the smoke cleared. Now it seems like I have some compression on the cylinder. I haven't run a compression test but there is more power.

Sounds like I have a broken ring.... or two. Still going to sell it. At 220K miles it isn't worth putting any money into it. Nice CLEAN AZ car? sure, maybe worth a rebuild but a SW Mich car in the heart of lake effect snow country with all of that salt? nope.

[eppoh]

You may just have a chunk of carbon wedged in the valve seat area.

Sometimes on those old 4 cyl flat airplane engines, when the compression is low,. we would "stake" the valves on that cyl.

Basically, the get a wooded stake, place it on top of the rocker above the valve and give it a few whacks with a heavy hammer. It actuates the valve and sometimes loosens the foreign object- compression come back up.

[Fairtax4me]

Sounds like it would work, but good luck getting a wooden block and a hammer between the engine and frame.