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Transmission Vaccum issues

Discussion in 'The Garage' started by 79CK454, Jan 15, 2005.

  1. 79CK454

    79CK454 Registered Member

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    Hey...New here Just bought a 79 Chevy 1/2 short box from a buddy of mine. He sold it to me thinking that the tanny was out. After lookin it over found out there was a vaccum hose on the tranny with a hole in it. I replaced the line and the part? ($10 fix) great......

    Well started it up, let it warm up topped off the tranny fluid and took off. 1st, 2nd, and 3rd shifted like it was new. Drove it about 10 miles, put it back to the shop to tweek some minor crap (shocks, rims & tires).

    Took it out. Only get about a mile sounded like it shifted to low. Blue/white?smoke out the dual exhaust. Would hardly run. Cripple home, oil had water or tranny fluid in it? Is this a head gasket issue? Vaccum issue? Any ideas I have not dug into into it yet. Worried!!

    Really strange, cause like I say it was fine for 10-15 miles with the new vaccum and hose? Any help would be much appreciated!!:cool1:
     
  2. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    vacuum modulator... motors sucking up tranny fluid...
     
  3. diesel4me

    diesel4me 1 ton status Premium Member

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    modulator????

    I might be the tranny vacuum modulator --the rubber diaphram in it might have failed,allowing engine vacuum to suck ATF out of the tranny and burn it in the motor...but I doubt it would show up in the engine oil,that sounds more like head gasket failure--the oil will look milky or like mayonaise in the valve covers or on the dipstick if water got in the motor from bad head gaskets or cracks...

    Somtimes a brake master cylinder leaks into the power brake booster and the brake fluid gets inhaled and burns in the motor ,causing lots of white smoke--usually it only does it a few times before your brake light on the dash will come on,due to the empty resivoiur in the master cylinder,and you'll notice the brake pedal will almost go to the floor...:crazy:

    Good luck!
     
  4. 79CK454

    79CK454 Registered Member

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    The part I re-placed wast the Vaccum Modulator

    I did check the dip stick looked almost milky caramel color. When the vaccum fails would would I still have oil pressure? I did still have oil pressure? Where should I begin.....New vaccum line and modulator? Thanks for the input!

    Chad
     
  5. Smitty

    Smitty 1/2 ton status

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    Check inside the vacuum hose on the modulator for transmission fluid. If it has fluid inside, change the modulator. As far as the water in the engine oil, I'd start checking for a blown head gasket. Good luck!
     
  6. Thunder

    Thunder 3/4 ton status

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    If your oil looks like a chocolate milkshake you have water in it. = Bad head gasket cracked head.
     
  7. 79CK454

    79CK454 Registered Member

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    What would it look like if the motor sucked in tranny fluid from the modulator going bad.... Or is that even possible? Thanks
     
  8. Smitty

    Smitty 1/2 ton status

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    The transmission fluid wouldn't get to the engine oil. It would be sucked into the intake manifold and would be burned with the fuel mixture. You'd notice a drop in the transmission fluid level and smoke out the exhaust pipe.


    It sounds like your main problem may be with the engine. You need to pinpoint the water and oil problem in the engine.
     
  9. diesel4me

    diesel4me 1 ton status Premium Member

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    take a sniff test

    If you bring it to a shop that does emission tests,they can tell you in a few seconds if your head gaskets are leaking by putting the probe they usually put up the tailpipe over the radiator cap opening with the cap off and engine running,any reading of hydrocarbons indicates a leak between the combustion chambers and water passages--could be cracks in head or block too....I've seen intake gaskets fail at the corners where they seal the water passages and leak into the lifter valley too--.

    I think I changed a set of head gaskets on one motor for nothing,when I saw the intake gasket was leaking--but I was 75 percent of the way there,so I just kept going,and changed them anyway--the motor ran great for about 3 weeks,then spun a bearing--probably due to being poisoned with prestone(anti-freeze eats bearing material after awhile!:blush: )...hope its not the case in your truck--I'd change the oil and run it,and see if it gets milky right away again--it might just be condensation from long storage that built up in the motor....:crazy:
     

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