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oil leak question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 79Cheyenne, Apr 11, 2000.

  1. 79Cheyenne

    79Cheyenne 1/2 ton status

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    I have gone through the engine and replaced every oil seal and gasket, and I still have an oil leak. The oil pan is dry around the gasket , the timing cover is dry, even the oil seal in the cover is dry but I have oil dripping down the front crossmember, it seems to be comming from the rear of the engine. Where is my oil sending unit and could it be the culprit. I'm about one more wasted weekend away from buying a crate motor[​IMG]. So please help

    thanks

    <font color=orange>1979 BLAZER Cheyenne[​IMG]
     
  2. Corey 78K5

    Corey 78K5 1 ton status

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    The oil sending unit is located on the block behind the distributor. Also if you have a auto tranny pull the flywheel cover off and look up between the block and flywheel with a flashlight (engine off) and check the rear main seal for leaks.
    Corey 78K5
     
  3. SVBlazer

    SVBlazer 1/2 ton status

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    Agree. As corny as this sounds, might want to check the front diff breather hose.
     
  4. **b**

    **b** 1/2 ton status

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    I just replaced the breather hose on my front diff...
    i think i still have a problem with an inner axel seal (drivers) though [​IMG]
    not sure if its still leaking or not...
    time to do a power wash i guess...
     
  5. Blazer1970

    Blazer1970 1/2 ton status

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    Valve covers, or the seal between the intake and the block at the back would be two of the most common leak locations.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  6. Blaze81

    Blaze81 Registered Member

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    Also might check the intake manifold bolts. I recently found oil puddling around the bolts on my intake. I had the same leak as you but couldn't find it till I looked on the intake. I just pulled them and resealed one at a time. leak GONE!!!.

    Tuck
     
  7. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I agree with the comment about the oil pressure sending unit. It is mounted on the rear of the motor, out of sight, and threads into the block. If it's come loose or the sealant(thread tape or pipe dope) has gapped, then you'll get a drip out of the orifice. One way to check is by watching your oil pressure gauge. Without a good seal on those threads, you may be experiencing what looks like low oil pressure......
     
  8. 79Cheyenne

    79Cheyenne 1/2 ton status

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    Since I have replaced the oil pump when I was in the oil pan, I have great oil pressure 45-60 psi. Its been solid bad weather to work on it, when the sun comes out Im going to replace the intake gaskets and the sending unit just to see if either one was it. While I am in this far any suggestions on what else to do?

    <font color=orange>1979 BLAZER Cheyenne[​IMG]
     
  9. SVBlazer

    SVBlazer 1/2 ton status

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    Well, if your that deep into the top end, might as well freshen the heads up. If you've got the time and $s, might want to have your friendly machine shop do some read head work. Do you have an aftermarket intake already? If not, now's the time. How about a new cam? These couple of items will truely liven' up the power...
     
  10. mudfanatic

    mudfanatic 1/2 ton status

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    on an old motor, you might not want to have your heads rebuilt, what if your rods have hairline cracks now but your engine is producing less HP and Torque than rated, it has all worn at the same rate. rebuild the heads and maybe have a rod break, or a bearing failure due to more down pressure than they're used to. However, if you want to take the heads off now might be a good time to put in a new cam, lifters and timing chain and gears, but i wouldn't go any more than stock cam on an old engine for the same reasons stated above.
    '77 K5

    <font color=red>mudfanatic</font color=red>[​IMG]
     

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