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1986 suburban smoking

This is a discussion on 1986 suburban smoking within the Technical / Maintenance forums, part of the General Discussion category; i have a 1986 silverado c10 suburban 700r4 auto with a Q-jet carbed 350. i bought it 5 months ago ...

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    1986 suburban smoking


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    i have a 1986 silverado c10 suburban 700r4 auto with a Q-jet carbed 350. i bought it 5 months ago from my neighbor whose owned it and meticulously maintained it since 92. it has 154,500 miles on it and as far as i can tell the motors never been taken apart aside from having the q jet taken off for repairs(still has original carb). it didnt burn any oil when i bought it, but now it makes large clouds of smoke, and fouls the drivers side rear plugs(5&7) almost immediately. we've only put 750 miles on it since we bought it, no smoke for 3 months, then tons from then on. i did put in a half dose of engine restorer and that stopped the smoke for a while, but now its back. I dont have my license, so ive only driven it 1/4 mile, and my parrents drove it the rest. dad did open it up a couple of times, but its only been taken it up to 75 mph.
    does this sound like rings, or valve stem seals that have rotted all the way out? i havent run a compression test yet, ill post the results when i do. also, its been smoking for about 150 miles, but i havent been able to tell any lost oil when i check it.

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    Re: 1986 suburban smoking

    also, i have the records for the first 3 oil changes, the book says to change the oil/filter every 7,500. the first 3 changes where spaced at 2 month intervals, and their mileages were, 5100, 8900, 12,500

  3. #3
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    Re: 1986 suburban smoking

    are definite that it is oil smoke and not steam (radiator coolant had a kinda sickly sweet smell when
    burned). with that many miles i'd expect the valve stems to be worn badly, no matter how meticulous
    the previous owner was.. when you check the compression, do a dry test first, then a wet test
    (squirt a little oil throught the spark plug hole). if the wet test give higher compression, then the
    rings are leaking too.

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