End of an era? Misfire, 25 PSI compression.

[axgutt]

Just after bragging to some friends about how my Legacy was going to last forever, I get a CEL. 1995 Legacy L wagon, 2.2, MT, 330k miles. I disconnected the battery for the day to reset the computer, and the CEL came back the next day. Idle was rough. My mechanic pulled a 301 code - misfire in cylinder 1. Stopped by his shop on my way home (having a spare vehicle is useful). He pulled the spark plug and it was clean. Did a quick compression test and that cylinder was only putting out about 25 PSI.

 

It sounds like this could be the end of the line. From what he described and from what I've read so far, to try and fix this would require pulling the engine and getting deep into the guts - probably not worth the effort given that it has a third of a million miles on it. Are there cheap/easy fixes worth trying or any miracle additives I should try dumping in somewhere?

[StructEngineer]

What are the readings on the rest of the cylinders and did he confirm rings by testing compression wet? Would also try a leakdown test before considering the engine junk. I wouldn't assume bad compression rings unless others are also showing signs of wear and until he first checks out the valves. Might want to run some seafoam through the intake...maybe you just have a really gunked up valve..

Edited April 21, 2010 by StructEngineer

[bheinen74]

Did he pull all 4 plugs when doing compression check test?

or just the one he pulled plug out of. Not sure his "quick test" is even valid.

sorry to hear about your misfire code.

[johnceggleston]

if the compression in #1 is also low it may be a slipped t-belt. but if it's good then i would guess burnt valve.

 

if so, i would swap in another engine and drive another quarter million miles. assuming you like the car.

[GeneralDisorder]

Compression test doesn't tell you sqaut - you need to do a leak down test.

 

But with that many miles - just drop in a used engine and be done with it.

 

GD

[WoodsWagon]

Probably a burnt exhaust valve, I've done in a couple. You can chuck a head on that side off of any other pre 96 2.2, or you could throw in any 90-98 2.2l in and use your intake manifold on it. 96-98 you will need to grab the single port y-pipe for the exhaust.

 

Used engines for these are cheap, $200-400. With some basic metric tools, a rented engine lift and a mechanically competent friend you could have it swapped out in a weekend.

 

Use the fuel injectors off of the replacement engine on your manifold, and send yours out for cleaning. I suspected an injector on my 2.2 as i burnt an exhaust valve, chucked on another head, and a couple months later burnt another valve on the same cylinder. Granted I beat the piss out of that engine every day of it's life but still, to have it go on the same cylinder seemed suspicious.

[Fairtax4me]

Make sure it's not a burnt valve first. If it is just a burnt valve, pull the heads and have a valve job done, or slap a replacement head from a junkyard engine on it.

 

If you have a valve spring compressor you can do your own valve job pretty easy as long as you don't need new seats. But any machine shop can press new seats into a ripped down head for practically pennies.

[StructEngineer]

to those who are recommending an entirely new engine for a burnt valve, are you recommending this because putting on a fresh head may end up blowing out the tired bottom end?

[Rooster2]

to those who are recommending an entirely new engine for a burnt valve, are you recommending this because putting on a fresh head may end up blowing out the tired bottom end?

 

My understanding regarding putting in a used engine is advantageous, because his existing engine is super high millage at around 325K miles. At that millage, it is reaching the end of it's useful life and reliability. A used 2.2 in good shape for $200-$400 is a better value then considering a partial or complete rebuild on the existing engine.

[WoodsWagon]

A new head will never "blow out" a tired bottom end. However, a tired bottom end that has oil consumption issues can leave oil/carbon build up on the exhaust valve, causing it to hang open and burn. I chucked a replacement head on my heavily abused bottom end, and burned the valves out of it too. Now that's a chicken and egg situation, was that cyl running hot and burning valves and rings because it was running lean due to a faulty injector, or was it burning valves because the rings were toasted and leaking oil though because I ran it out of oil for a while?

 

A head either works or it doesn't. If the valves are leaking enough to affect combustion pressures, they will burn. They depend on a tight seal on the seat to dissapate the heat out of the valve into the head.

 

I'd chuck a used engine in, just because it would be cheaper if you count in all the parts you end up replacing when you do the headgasket and it's less work. The EJ22's are easy to slap heads on and off of because the headbolts are all external to the valvecover, but still, by the time you pulled a head in the junkyard, dropped the exhaust, pulled the intake, drained the coolant, removed and replaced the timing belt and swapped heads and new headgaskets, you could have thrown in an engine with 100k on it for the same effort.

 

It all depends on the body. If it's a rustbucket, like holes in the rockers and over the rear wheel wells, then don't bother. If it's in good shape, spend the $300 and a weekend and get it swapped out. It's not hard.

 

One other alternative is pulling the plug off of the injector feeding the dead cylinder. It won't harm anything, and it helps keep the cat from being cooked. All the other cylinders will run rich because of the extra air giving a lean signal to the O2 sensor, but I used to commute 80 miles a day running on 3 for a few weeks before swapping heads or engine. 30" tires and 3 cylinders kind of sucked, but it was probably making more power on 3 cylinders than the origonal EA82 made on all 4.

[GeneralDisorder]

A new or rebuilt head on a tired bottom end can result in higher cylinder pressure's and can cause more rapid failure of worn rod bearings, etc. Subaru's don't typically wear their bore or rings much - what gets them is the rod bearings.

 

At the mileage indicated - there's just no point in trying to fix it. Chances are that something else will fail sooner rather than later.

 

Used engine - resealed, new timing belt/WP kit. Easily doable for $500 or less.

 

GD

[axgutt]

I think I'll give the Seafoam a try this weekend. I know 1/3 goes in an intake, 1/3 in the oil filler, and 1/3 in the gas tank. I've read a few different things about which hose to use to suck it into the engine though. The problem is in cylinder #1. Should I go through the PCV valve?

 

Adam

 

What are the readings on the rest of the cylinders and did he confirm rings by testing compression wet? Would also try a leakdown test before considering the engine junk. I wouldn't assume bad compression rings unless others are also showing signs of wear and until he first checks out the valves. Might want to run some seafoam through the intake...maybe you just have a really gunked up valve..

[WoodsWagon]

Go through one of the capped ported vacuum sorces on the top of the throttle body. Pull the cap off, hook a vacuum hose to it, and use the hose to suck the seafoam out of the container. You'll have to manually open the throttle while it's running to get a vacuum signal on the ported vacuum line.

 

Don't put any in the oil, and putting it in the gas won't do anything either. It's most useful in the intake, and probably detrimental if you put it in the oil and drive the car.

 

Use a bottle of "Techron" by Chevron fuel system cleaner, it's the only stuff I've found to acually work for cleaning the injectors. Though, I'm afraid that horse has left the barn so to say as the injector on the dead cylinder was probably running lean for a while before the valve burned.

 

You can't bring burnt valves back from the dead with seafoam. 25psi indicates a serious problem with that cylinder, and not one seafoam will remedy in all likelyhood.

[Mike104]

"Don't put any in the oil"

 

I'll second that! I put some in my engine oil on my 99 and all the oil seals started to leak! It may have just removed the gunk that was keeping them from leaking but it was an expensive fix!

 

I use Techron as well in the gas tank every oil change. Cheap maintenance IMO.

[GeneralDisorder]

Agreed - you are throwing money away on Seafoam - save it for the replacement used engine .

 

Even then - it's not the miracle product people seem to think it is. The Techron stuff is ok for cleaning injectors - pricey too.

 

There just aren't many products that make any kind of sense from a "repair in a bottle" perspective. Techron can help over time though just pulling the injectors and having them cleaned is probably about the same price after you run enough bottles of Techron through to do a really good job. ATF or Rislone make excelent oil additives for *very specific* types of symtoms....

 

Under normal circumstance it's best to just run what the owners manual calls for with regard to fluids and leave the repairs to folks with wrenches.

 

GD

[StructEngineer]

As mentioned before just use one of the vacuum hoses on the intake. I would suggest adding it to the hose with a small funnel instead of sticking the hose in the bottle. You dont want to add too much at once so you dont hydrolock.

 

I wouldn't add it to the crankcase. Just run it through the intake. $8 and 5 min isn't a waste.

[eppoh]

There is another possibility- that is a broken or weakened valve spring. The only way to tell is to start with a leak down check, and listen for the leak in the intake or exhaust. If it is a valve leaking, pull that valve cover and look at the spring.

 

I have seen this once before.