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Oil Leak

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sickquad, Jan 9, 2004.

  1. sickquad

    sickquad 1/2 ton status

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    I have a new GM 350 crate motor with a small oil leak coming from the back top of the motor. It's not the oil pressure sender unit and it doesn't look like it's the distributer gasket. Can it possibly be the back intake mainifold gasket? I used the black silicone when I sealed the front and back of the intake manifold. I am not sure if there is a oil passage that goes up to the manifold? Any ideas? It seams to me right now that it can only be the intake manifold.

    Thanks
    Chris
     
  2. oatsk5

    oatsk5 1/2 ton status Premium Member GMOTM Winner

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    I have been told that on t he newer 350 its a common problem with the intake gaskets so you might start there i no thats not the best news but thats my thought . /forums/images/graemlins/thumb.gif
     
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    It is probably either the intake manifold or the valve cover gaskets. I have had problems with the cork type valve cover gaskets with my new 406 and they were leaking terribly right after I put the motor in and thought it was the intake too. Then I noticed the valve covers looking wet( oily wet look) and noticed a little oil puddling around the intake bolts. I quickly tightened all the valve cover bolts, found that they got very loose, and no more motor leak after that. The book said 5 to 8 lbs for the bolts but it wasn't tight enough.
     
  4. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Did you use a gasket on the back of the intake, or just the sealant? Could be if you used a gasket with the sealant, that you overtightened the intake, and crushed the gasket. That would definitely cause a leak.
    -Harrison
     
  5. sickquad

    sickquad 1/2 ton status

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    I didn't think of the valve cover gaskets, could be drooling down. I'll take a look at it.

    I didn't use the front and rear rubber gaskets that came with my intake gasket set. I was told to throw them out and use the black silicone only.

    I really don't want to have to take my intake manifold off, but I think I may have too if it's not the valve covers.

    Another question, what is the best gasket material? Cork? I know you can get rubber gaskets and also white fiber gaskets. I have always used cork and this is my first mystery leak.

    Thanks
    Chris
     
  6. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    A lot of people have trouble with leaky valve covers and it runs sown the back of the motor and drips off the starter. Since you just used silicone for the intake ends I doubt that is the problem. The best valve cover gasket that I have heard is RTV hi temp silicone like what you used on your intake. The cork gaskets suck.
     
  7. sickquad

    sickquad 1/2 ton status

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    Yup, it was the valve covers. Tightened to 10 ft-lbs and no leak. Thanks for the help.
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    Yup, it was the valve covers. Tightened to 10 ft-lbs and no leak. Thanks for the help.

    [/ QUOTE ]
    Awesome, they can leak a suprising amount of oil. /forums/images/graemlins/blush.gif Check them again in a couple of weeks because I retorqued mine too but they came loose again. An easy way to tell if they are leaking is if you can see fresh oil on the starter or on the front driveshaft yoke. Thats how I tell.
     
  9. sickquad

    sickquad 1/2 ton status

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    Wondering if I can get some locking clips for the bolts if this is a reaccuring problem, maybe it's just the new gaskets. Similar to the locking bolts on headers.
     
  10. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I'm not too sure. I am going to check mine tommorrow and see if they are still tight. /forums/images/graemlins/thinking.gif
     
  11. 85scottsdale

    85scottsdale 1/2 ton status

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    My valve cover bolts just get loose after awhile, I have the T-Handle bolts though so it just takes opening the hood and turning them with my hand, I love those T-handles.
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Valve cover leaks are why I got aluminum valve covers. I paid $5 for them from a friend, and no more leaks! Aluminum valve covers ROCK!!

    Rene, aka TrustK5 turned me on to the aluminum covers back in his gas powered K5 days. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  13. lukebaby1

    lukebaby1 1/2 ton status

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    The best valve cover gaskets that I have found, and now swear by are "Earls Pressure Master". They are available through Summit Racing Part number EAR-29E03B. These things are great! No messy sealer has to be used, they are reuseable, and are pretty tough. I have three sets in use and have not had the first leak from those notoriously leaky old style small block chevy valve covers. They are a little pricey though at fifty dollars a set, but well worth it, for the headaches they save you from. The best way I can describe them is, an O-ring type gasket with a center aluminum frame. These guys definitly did their homework, when they came up with these. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/thumb.gif
     
  14. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Fel-Pro makes the same type gasket, and it's not $50!!
     
  15. audacious

    audacious Registered Member

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    i agree fel-pro is the way to go and i use the T-handles since mine still come loose from time to time when i run it hard. /forums/images/graemlins/k5.gif
     
  16. lukebaby1

    lukebaby1 1/2 ton status

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    Hey Tim, you wouldn't happen to know the felpro part number for that gasket thats like the Earls? I would like to check that out. I thought Earls had a patent on theirs.
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    Hey Tim, you wouldn't happen to know the felpro part number for that gasket thats like the Earls? I would like to check that out. I thought Earls had a patent on theirs.

    [/ QUOTE ]

    I don't have a part number, but it's called a Perma-Torque gasket, it's very common.
     
  18. lukebaby1

    lukebaby1 1/2 ton status

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    I checked out the perma torque, its not the same as the Earls, not as stiff, and uses a different material. No anti crush sleeves, like the Earls. /forums/images/graemlins/grin.gif
     
  19. sickquad

    sickquad 1/2 ton status

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    Just looked at the Earl's in Summit, I like them. Also just dug up a set of Edelbrock aluminum valve covers for free. This thing will not leak when I'm done with it.

    -Chris
     
  20. lukebaby1

    lukebaby1 1/2 ton status

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    I have used the edelbrock in combo with the Earls. They work pretty good just make sure that the mating surface on the Edelbrock's are smooth. Alot of them have these little round indented circle casting marks that you might want to sand down smooth. I found that (if you can find them) the 1980-84 corvette factory aluminium valve covers (which also came on the Z28 Camaro) work very well and seem to give a better fit than the edelbrock. Not to put down the Edelbrock which is good, especially if their free. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     

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