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Oil from dipstick tube

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 87GMC, Nov 27, 2003.

  1. 87GMC

    87GMC 1/2 ton status

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    My engine is pumping a lot of oil out the dipstick tube, about 1.5 qts for a 20 mile drive. I did a compression test and the #3 cylinder is way low. How do I tell if it's the head gasket or bad rings? I'm guessing if it's bad rings the cylinder wouldn't build enough pressure to cause that much pressure in the crankcase. So I'm guessing the head gasket is leaking the compression into the crankcase.
    Does this sound right?
     
  2. Confedneck

    Confedneck 3/4 ton status

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    the headgasket wont let compression past the RINGS into the crankcase, i bet youve got bad rings in 3...
     
  3. Okiemuddog

    Okiemuddog 1/2 ton status

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    Yup, got classic blow-by, my engine I just took out was doing the same thing. The only way to tell if it the head of the ring it to do a wet test, shoot some oil in the cylinder, if you get compression it is the rings, still no compression then it is the head. The oil will form a seal and let the cylinder compress if the rings are leaking, but if you can still not get compression the you have got a head problem.

    Probably time to start looking for another engine or looking into a rebuild.

    Krennen
     
  4. HarryH3

    HarryH3 1 ton status Author

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    That's a classic symptom of excessive blowby. /forums/images/graemlins/frown.gif Remove the oil filler cap with the engine running, and you'll probably be able to feel the breeze coming out of the crankcase. /forums/images/graemlins/eek.gif
     
  5. k20

    k20 3/4 ton status

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    Ive had that happen firsthand. Rings are gone, come to think of it, i think #3 was bad on mine. Anywho, if you have plans for a new engine, you can always do a temp patch of putting a breather on the valve cover in place of the oil fill cap. I did it, only prob is that everything under the hood gets a nice oil film on it. But it should last a while. If you dont have plans for it, go ahead and rering it soon before it causes other damage.
     
  6. 87GMC

    87GMC 1/2 ton status

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    Thanks for the help. Do bad rings usually damage the cylinder walls enough to need rebored or will a hone normally be sufficient?
     
  7. k5guyva

    k5guyva 1/2 ton status

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    Usually you need to bore the whole thing out. That is unless you like having to do it again. Cylinders wear in an eliptical pattern and that has to be bored out to match the new pistons.
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    Thanks for the help. Do bad rings usually damage the cylinder walls enough to need rebored or will a hone normally be sufficient?

    [/ QUOTE ]

    You will have to mic the cylinders to find out. I have found that many engines can be honed as they generally don't get out of spec unless something funky was going on. Many that I thought were screwed up came up in spec for out of round, taper, etc. I ran the hone down them, re-ringed 'em and sent them on their way!!
     

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