Burnt / cracked exhaust valve 2.5 DOHC - now fixed Hey everyone, gas powerd things at my house are not doing me any favors lately. My 99 Legacy Outback 2.5 DOHC has only 50psi on cylinder 4 and 190-200 on the other three. CEL is on, naturally, and sometimes flashes because of an occational miss-fire (not constantly). I have the skills and such to fix it myself, but I don't have the time. I also don't have the cash for a dealer fix (I'm guessing in the $1800-$2200 range at a dealer), does anyone know of a reputable place to go for a better-than-dealer price? I could help with the work, but as our schedules are, I don't have the luxury of doing it after work over the course of a few days. My wife is driving it now (yes, even with the bad cylinder) because her van died, no oil to top of rear head on a Chrysler 3.3 v6, and I'm strictly riding motorcycle, rain or shine. Motorcycle needs carb work, and the wife's van needs to be replaced (almost 200k miles, not really worth fixing), so an ecconomical fix is needed. Can anyone help?
id take care of it for ya but my shop is in the midst of a move right now. how do you know its burnt, or cracked?
I have a misfire code for #4. In the process of diagnosing the issue I replaced plug wires and plugs, cause I knew it was time for them to be changed. And replaced injector, based on other searches about misfires. All of these things helped to an extent, but still throwing P0304 code. Also, an 'exhaust leak' sound developed. I then bought a compression tester and got the results posted above. At this time I went back and re-examined the plugs that I replaced. Three are all the same, light tan and looked good. The one from #4 is more of a medium brown and smells like exhaust, as does the new one from #4. So now I am guessing that the exhaust valve on #4 is not closing (fouled or burnt) or is cracked, causing the low compression, misfire, rough idle, exhaust leak sort of sound, and now poorer gas milage than before. If you have other ideas as to what could be the issues, please let me know. I'd like to get this fixed right, and I need it soon
This sounds like it could also be a set of fried piston rings. Are you burning excessive amounts of oil?
No, no oil burning, and no indication on the plug that it is burning oil. I do not believe that it is a ring problem.
Oops. Not to bright (ie. can't read plugs). When you say exhaust leak, is it a whistling (to-atmosphere leak) or more internal? I've never personally heard internal leaking, rather just a lot more noise because the combustion chamber isn't sealed correctly.
well you'll know when the head comes off. since you are there replacing that valve you might as well clean them all and lap em. you should also re-lash and adjust all clearances also.
Well, it's fixed. I did it all myself except for the head work. The removal/install was done at home in my garage, over the course of two and a half days. I did not pull the engine, just the one head. Lots of stuff cleaned up in the process, and also a right side axle replacement, since there was a large slice in the inner cv joint boot. It's just easier to replace the axle than just the boot, besides then I know the condition of the joint. Walser Subaru un Burnsville was nice enought to match the mnsubaru discount that BPSubaru gives, YEAH! Sorry not picture of the work in progress, but here is the valve that was replaced:
