SOHC EJ25: Valve stem seals?

Discussion in 'General Motoring' started by duncanmcrae, Sep 19, 2007.

  1. duncanmcrae

    duncanmcrae Guest

    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
     
    duncanmcrae, Sep 19, 2007
    #1
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  2. duncanmcrae

    Todd H. Guest

    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., Sep 19, 2007
    #2
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  3. duncanmcrae

    houndman Guest

    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
     
    houndman, Sep 19, 2007
    #3
  4. duncanmcrae

    AS Guest

    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!
     
    AS, Sep 19, 2007
    #4
  5. 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.
     
    Clifford Heath, Sep 19, 2007
    #5
  6. duncanmcrae

    duncanmcrae Guest

    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
     
    duncanmcrae, Sep 19, 2007
    #6
  7. duncanmcrae

    houndman Guest

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

    VF
     
    houndman, Sep 20, 2007
    #7
  8. duncanmcrae

    alf Guest

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

    A.
     
    alf, Sep 20, 2007
    #8
  9. duncanmcrae

    duncanmcrae Guest

    yes.. and I understand that
    a) compression rings are ok (given the compression test)
    b) rings, any rings, require major surgery.
     
    duncanmcrae, Sep 20, 2007
    #9
  10. duncanmcrae

    houndman Guest

    what is the oil consumption?
     
    houndman, Sep 20, 2007
    #10
  11. duncanmcrae

    duncanmcrae Guest

    I think its about 1l/1000k.. haven't actually quantified it, but I
    need to top up (250-500ml) every couple of weeks.
     
    duncanmcrae, Sep 20, 2007
    #11
  12. duncanmcrae

    Kim W Guest

    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
     
    Kim W, Sep 25, 2007
    #12
  13. duncanmcrae

    Al Guest

    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
     
    Al, Sep 25, 2007
    #13
  14. duncanmcrae

    houndman Guest


    what other causes could there be?

    VF
     
    houndman, Sep 26, 2007
    #14
  15. duncanmcrae

    duncanmcrae Guest

    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?
     
    duncanmcrae, Sep 26, 2007
    #15
  16. duncanmcrae

    duncanmcrae Guest

    (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

    http://i113.photobucket.com/albums/n229/dennis_8047/Subaru Motor/Drivers_valvetrain.jpg

    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
     
    duncanmcrae, Sep 26, 2007
    #16
  17. duncanmcrae

    Kim W Guest

    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
     
    Kim W, Sep 30, 2007
    #17
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