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Exhaust Smoke

Discussion in '80-Series Tech' started by otis22, Mar 18, 2004.

  1. otis22

    otis22

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    I have a 1996 80 with approximately 110K. I do regular oil changes with redline 15w-40. I notice that every morning starting up, smoke comes from the exhaust pipe for about 20 seconds. It doesn't smoke under startup or during operation in other conditions, its only when its been sitting for a while. Its hard to determine if it really white or blue, I would say somewhere in between. The smoke has a heavy gas smell to it. My radiator is clean with no gunk and the oil usage and appearance is normal. The car does knock from time to time under light acceleration. Can someone give me some insight as how to find out if this is a fuel/air mix problem or something more related to a mechanical failure in the engine. Thanks for your input Justin
     
  2. sjcruiser

    sjcruiser

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    Justin,

    Are you sure it's not water condensation (steam like) ? It happens to any cars when temp. is low.

    Frank.
     
  3. otis22

    otis22

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    Its definitely smoke as my wife drive down the street it leaves a residual trail for 20 or 30 feet that lingers in the air. I live in Los Angeles, so it doesn't get overly cold down here, but its something I did consider early on.
     
  4. turbocruiser

    turbocruiser SILVER Star

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    My experience with extra smoke at startup is that it relates to leaking valve stem seals; the seals leak slowly over time or over night and then upon startup the oil is combusted and causes smoky exhaust. Just a guess. HTH
     
  5. Gumby

    Gumby Supamod Staff Member s-Moderator

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    leaky valve stem seals if it is not condensation.
     
  6. otis22

    otis22

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    is a leaky valve stem seal a critcal repair or can wait until other maintenance needs to be done to the head? Thks
     
  7. turbocruiser

    turbocruiser SILVER Star

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    [quote author=otis22 link=board=2;threadid=13352;start=msg123544#msg123544 date=1079658216]
    is a leaky valve stem seal a critcal repair or can wait until other maintenance needs to be done to the head? Thks
    [/quote]

    Well, that depends; a leaky vavle stem seal is not likely to cause a catastrophic failure, on the other hand, it will gum up the works at least in that cylinder. You could start missing or running roughly as the spark plug gets fouled. You can also consume oil. If it were me, I would fix it but also fix anything at all that can also be fixed while you are in there so that you do not pay duplicate labor charges down the road. Others will probably say not to worry til its' worse. HTH.
     
  8. xl715

    xl715

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    I would make sure it's oil that is causing the smoke. If your valve stem seals are leaking and causing the smoke thats one thing, but to just say you have some smoke on cold start up, when your catalitic converter has not even fired off yet is one heck of a crap shoot. If you don't have the experience to diognose it yourself take it to the dealer and leave it over night so they can do a cold start first thing in the morning. Would sure pay off if it's just gasses that aren't being burnt by the cat due to it being cold!! Would hate to see you waste all that money to replace good seals, just my 2 cents!!
     
  9. Photo_Cruiser

    Photo_Cruiser

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    Thought I'd read this thread and turns out I have a similar condition....I've had it for the 1/1/2 years I've owned the rig....at startup in the morning, the exhaust is slightly smokey and has a pretty good whif of fuel or just really strong stinkin' exhaust. I'm a one banana mechanic..maybe two, so I've always thought it was in relation to the high idle at start, which I also have. After about 20 or so seconds the idle calms down, and the smoke ceases as does the smell...I am not attempting seals, but was going to either clean the throttle body, or go for the high idle fix...to rectify this...can a test be done to check the seals, or is it a tear into it type of thing...

    On another note...I don't know if any of you remember, but I had my engine, about 6 months ago, spit out a spark plug and shred some wires..fortunately the threads were not damaged on the head, and all is well now, but could this leaking seal ( remember I am one banana ), if it is a leaking seal, increase or change pressure or do some kind of something that could have caused my spark plug incident...If it is a seal, I'd want to fix it yesterday...ya know...this is my baby we're talking about...
     
  10. xl715

    xl715

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    Cruiser, a leaky valve seal would not be related to a spit out plug. Your description of the smoke is a lot more clear, it sounds like unburnt fuel that would normally be picked up by the catalitic converter and converted to carbon dioxide, however the cat only works when it is hot, thus the raw fuel smoke when engine is cold. My rig does it also, and the high cold idle would alow more fuel to pass thru, however I really don't think anything you did to try and stop this would really make that much diference. Lowering the idle may limit some of the fuel that is exiting the exhaust, however the cat is still cold and it would probably still have the smell/smoke.
     
  11. Lars

    Lars

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    I bought my 93 and drove it for a few weeks before things took a turn for the worse. Occasionally I noticed a little smoke at startup. It had an oil/fuel smell to it. One of the last times I drove it, I noticed the smoke at startup was now predominently steam and as I returned home from a 5 mile trip to the mall, the engine started idling roughly. I checked for all the symptoms of a head gasket failure and sure enough....... I was cursed.

    When I pulled the spark plugs, the #3 plug was fouled. Also, after taking the head to have it inspected, we discovered the #3 cylinder valves were leaking.

    Two symptoms and two different issues.

    If it were me, I would at least pull and inspect the plugs, maybe do a compression test or to do it right I would have a leak down test performed.
     
  12. anderaa13

    anderaa13

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    My 93 smokes on morning starts. Mine is oil smoke from leaking valve stem seals. It has been doing it for a year or two and I do have significant oil consumtion (1qt./1500mi). It's always had excellent maint, no overheating, etc. and compression was recently tested at right around 175 on all cylinders. I've pretty much decided not to worry about it unless it starts fouling plugs or consumption gets out of hand.
    aaron