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Coolant leak...

Discussion in 'General Chevy & GM Tech Questions' started by Jcloud, Jul 9, 2010.

  1. Jcloud

    Jcloud Rockstar

    I have a 1998 k1500 z71 and I have a coolant leak and not sure where it is coming from. When I'm parked on a flat surface it will drip down where the engine and transmisson meet. But when I'm parked on an angle surface it won't really leak. Any help is appreciated! Thanks
  2. Danow

    Danow Member

    I had the same thing on my 2001 chevy silverado. Never could find the leak. What I found was the water pump gasket leaking. The old gasket is the metallic with the small bead of rubber. I changed out my pump due to the age but the new pump had a better gasket. When I removed the old pump you could see where it was leaking by. I haven't seen a leak since I did this repair. The leak would be toward the back of the engine on the ground. It would just migrate there. Hope this helps you.
  3. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    The intake manifold gaskets can leak and dribble down the back of the motor and the "front" of the transmission.

    I would certainly try to find a more traditional coolant leak first-like Danow's leak.

    Try to get a mirror under there to find the actual origin of the leak. It is really tough sometimes-getting under a truck and staring up to find the leak.If you jack it up-make sure you jackstand and block it before you go under.

  4. Danow

    Danow Member

    I was told the same thing by some friends, so I took off the vortec housing and all for nothing. There are no water jackets in the intake manifold of the vortec. The leak seemed like it came from the rear of the engine. I would search and search until one day I saw a little wetness under the waterpump. The chevy engines with water jackets in the intake manifold did have problems. I also had a malibu with that problem. It had a two part intake manifold. You have to remove rocker arms and push rods for it. All due to the Dexcool ( orange coolant ).
  5. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Danow-I'm relatively new to GM, but I'm 99% sure that the two piece intake manifold on my 1998 Suburban-5.7- does have coolant passages, and the gaskets are prone to leaking.
    The newest gasket sets are supposed to "fix" the problem.

    Look at this- it shows an horrendous leak on a Vortec(might be a 4.3, but a vortec)

    Like I said- new to GM, but the 5.7 does have coolant passages in the intake manifolds(almost all motors do new I think)

    This video shows the actual gaskets with passages that are for coolant
    Last edited: Jul 9, 2010
  6. Danow

    Danow Member

    I guess I am wrong about some of the Vortex engines but my 4.8 has no water jackets. I had removed it and took pictures of it to show a friend at work that told me that I was loony. : ) It is a one piece plastic body. He was still in unbelief but verified it with someone else.
  7. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    I replaced mine about 9 months ago with the newest fancy gasket set from one of the aftermarket gasket makers- #58000 something or other. It looked fairly rugged-so far so good- but new gaskets usually last 40,000-80,000 miles, so who knows.

    I had several coolant leaks-one after the other.
    1)Radiator leaked-replaced it
    2)Waterpump started leaking soon after I replaced the radiator-maybe the leaky radiator was keeping the pressure down and the increased pressure finally did in the pump seals??
    3)Intake manifold gaskets were leaking and dribbling back to the junction of the motor and trans-

    My 98 Suburban has 213,500 miles on it(I bought it with 195,500 3 years ago) so I can't complain. Very reliable and gets 21 mpg on long hy trips.If I had know a Suburban could get 21 mpg I would have bought one 15 years ago.My Titan and Tundra never got over 19mpg and the Pilot barely beat it(22 mpg), despite having almost 3 feet less interior length(we sleep in the Suburban when we travel-wife and one or two biggish dogs))
  8. Jcloud

    Jcloud Rockstar

    I took my truck to a shop today and had a pressure test done and they mechanic told me coolant just started pouring out of my engine and said he recommend me not to drive it anymore until it gets repaired. So there replacing my intake manifold gasket so hopefully that solves all the coolant leaks
  9. Danow

    Danow Member

    Good thing you found it. I should have pressurized my system to find the leak. I wonder how many of the Vortec engines don't have water going through the intake like mine. Since I changed out the gasket on my water pump I have been leak free. I am not a fan of the Dexcool ... my wifes Jeep Liberty has it also and it is eating into the block at her water pump .... so I have to remove it periodically and re-seal it. I guess I need to flush her system.
  10. Danow

    Danow Member

    My driveway is pitched up so naturally my leak would be at the back of the engine. I would see drips of coolant there but the leak was the water pump. At least I don't have to worry about the intake manifold ever leaking on my truck.

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