SOHC EJ25: Valve stem seals?

My (Oz-built) '99 outback (US Legacy/liberty) is smoking like a chimney. Engine is SOHC (phase-2?)

It seems to be valve stem related.

1) Compression is good and matched, 2) There is no oil in water or water in oil. 3) mechanic says no obvious sign of any one plug fouled.. all look the same (which puzzles me a little)

Smoking (blue, oil smelling) is upon first acceleration after periods of compression braking or idling. Car has done about 120k kms; service history is somewhat unknown (we purchased approx 12 months ago.. the smoking problem has been slowly increasing since then).

My questions are: - Are valve stem seals a known failure mode on the ej25? I haven't found any other references to this problem... it is possible the car spent much of its life idle, as the mileage was low for the age (10k/ year) - Is it possible I've dropped an exhaust valve guide, given 3) above? Wouldn't this give me marginal compression on one cylinder? Can this be checked by dropping the exhaust manifolds?

Mechanic wants AU$3k to pull the motor and rebuild the heads (plus $$ if he finds more to do, no doubt) . so I'm looking for a somewhat less costly option.. (other than pumping it full of stop-smoke, 60-weight oil and trading it in at the nearest car dealer, which is what I suspect happened when we bought it)

Given a stem-seal diagnosis: - Can I change the stem seals without removing the engine? I know this is possible in general (compressed air, rope in cylinders etc), but wonder about accessibility on the boxer. I know this will involve removing timing belt, cams etc. I did the timing belt myself not too long ago (100k) and it wasn't a big hassle. - If I can't change seals in-car, can I remove the heads without pulling the engine? I'll send the heads off to a shop to do.

any thoughts appreciated.

duncan

Reply to
duncanmcrae
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For what it's worth, an independent here charged me just $1800 to rebuild both heads in my 2.5L H-4.

But that was after I'd spent $2200 in mostly preventive crap with him, and he flat rated some of the work because of the volume discount you could say. :-)

Wish I could help more, but I thought I'd throw that datapoint out at ya.

-- Todd H.

2001 Legacy Outback Wagon, 2.5L H-4 Chicago, Illinois USA
Reply to
Todd H.

I only think valve seals when there is blue smoke when first starting after the car has sat for a while. Not that familiar with the Boxer motor, and how oil drains back to the pan.

Oil burning while the motor is running, I think first that the rings might be stuck in the gruves, on an older motor. I think when a motor starts to wear, the PCV valve recycles and burns the oil vapors (blow by), and once it starts, and if it makes the rings stick, it will just get worse and worse. I got a motor that was burning a qt every 30 miles on the highway, up to 550mi/qt. Thinking the rings might be gummed and stuck. I poured a little crancase flush down the carb, pulled the coil wire, cranked the motor, to try to suck it into the cyls, and not burn it off. Let it sit overnite, and drove it the next day. Gradually consumption would go down, till it maxed at 550mi/, and I would stop treating it. Then it would start dropping off. One mechanic said ALL I was doing was getting Oil in the rings, and forming a temp seal..... I would Think I had a Ton of oil getting to the rings from the burning. Another said he used to pull the plugs, and squirt GM Top Oil in each cyl, and never thought of pouring it down the carb..

I was buying the flush at Sears, and when the labels on the can changed, it stopped working. I Think the label change may have meant a different supplier was suppling it, and a different mix of solvents, that didn't work. The car was old to start with, and I got another yr out of it, and got another car, so didn't worry about it.

Don't know how you would get the solvent in if you have FI, but there should be a way, or pull the plugs and squirt it in, but that would be a chore.

Ran into a guy I know last week outside Pep Boys, and he was adding a few qts of oil to a work truck. I started to tell him what to try, and he said a mechanic at a shop that had a few antique cars did something similar, that lasted a while.

VF

Reply to
houndman

From what you say, it seems to be valve seals related, because it is there only when there is good manifold vacuum. Being a horizontal, there is no reason for the problem to be present when first starting the engine.

Did you check the PCV function?

You could end up replacing the piston rings too.

Good luck!

snipped-for-privacy@my-dejanews.com wrote:

Reply to
AS

After we had a similar job done (in Bright, Victoria) to fix the DOHC head gasket in our Liberty, I was told by our new mechanic here in Melbourne that there's no need to pull the engine to do the heads. Just another data point for you, no idea whether it's true.

Reply to
Clifford Heath

Yes,, I forgot to add that. Both mechanic and I checked the PCV independently

I don't suspect piston rings, given the behaviour..

If it comes to that, I'm offloading the car or swapping the engine.

duncan

Reply to
duncanmcrae

I believe there are compression rings, and oil scraping rings.

VF

Reply to
houndman

also FWIW: Subaru dealership service in Naperville, IL quoted both head gaskets replacement for $1400-1500.

A.

Reply to
alf

yes.. and I understand that a) compression rings are ok (given the compression test) b) rings, any rings, require major surgery.

Reply to
duncanmcrae

what is the oil consumption?

Reply to
houndman

I think its about 1l/1000k.. haven't actually quantified it, but I need to top up (250-500ml) every couple of weeks.

Reply to
duncanmcrae

My 99 Outback, also Australian, at 205000 km is running like new. Unless there has been some trauma with the engine I would not suspect piston rings or valve stem seals. I would look for other causes. Kim W

Reply to
Kim W

My '66 Corvair had leaking valve stem seals.It was a horizontally opposed, air cooled 6 cyl. engine. The smoke was the worst when going down hill with no gas applied. The oil would pull into the cylinders past the seals. The seals were a rubber type that could not handle the temperatures. The problem was fixed by replacing the rubber seals with nitril seals. This became noticeable after about 60,000 miles.

Al

Reply to
Al

what other causes could there be?

VF

Reply to
houndman

Neither would I.. but I think we've pretty much ruled out everything except valve stem seals.

My only thoughts on why they may have gone bad: - previous owner had car sitting for a long time and they dried out (no pool of oil sitting on top of them like in an upright engine design). - I've dropped a valve guide (ie: random failure)

I have.. any suggestions other than PCV valve?

Reply to
duncanmcrae

(talking to himself..)

I've had a poke around a few service manuals, and it seems I should be able to change the seals without getting anywhere near the timing belt.. if the cam assembly looks anything like this

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Frmo the looks of this, I should be able to:

- remove cam covers - remove rocker assemblies - operate on valves. - 'installation is a reversal of the removal procedure'

Anyone know if this is the case?? If so, the job is fairly straightforward.

duncan

Reply to
duncanmcrae

Since you don't know the history of the car I suspect that its had a hard life and possibly poor or no service. My experience with older Subarus (EA

81) suggests that valve stem seals can contribute to smoke on start-up and on down hill coasting - but not enough to cause significant oil consumption. Replacing the seals in situ would be a very challenging job! Bye Kim W
Reply to
Kim W

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