Intake Gasket

Discussion in 'Chevy Tahoe Forum (GMC Yukon, Cadillac Escalade)' started by 909, Apr 30, 2007.

  1. 909

    909 New Member

    Hi, new here. I have a '96 sub 4x4 350. I got it with a few problems and it's developed a couple in the past month that are really starting to agrivate me. Maybe you guys can give me some pointers to figure this out.

    First off, it developed an oil leak. Not the little drip every now and again, but the "Harley" type leak. You know, the kind where it stops leaking and you know you're out of oil! My neighbor is a mech. over at the local dealer. Says it's more than likely the pan gasket, says he's seen a bunch of them go bad for every main that does. All I know is that it's dripping from the hole in the trans inspection cover.

    Problem #2 is that today, I was topping off the oil etc.. and noticed, no coolant in the puke tank. Checked the radiator and it only took a couple cups to fill it but I checked it not long ago and filled the tank to the hot mark. Last time I filled it, I had just replaced the water pump so I figured it was still pushing bubbles out and sucked in all the fluid.

    So at more careful inspection, I see no frothing on the dip stick, but there is for sure a bit of oil in the coolant. I replaced the rad cap when I did the water pump, and now there is an oil residue on the bottom of the cap. I haven't pulled the plugs YET.

    From my experience on the SBC, the intake manifold gaskets used to leak all the time. I came up with a sure fire way to seal them for good, but the leaks were always oil, not coolant. Now besides this sub, I have zero experience with the vortec engines. I have a '94 K1500 that has 280k miles on a stock engine, but that isn't the vortec. I know this was the first year on 'em so I guess here is the real question. Can the water and oil leak be from the rear intake manifold seal? I had a similar experience on my corvette where the rear seal popped, dumped oil down the back of the block, where it ran into the trans inspection cover where it looked like a rear main leak. Does this happen? Where would I need to check for things? Should I do the head gaskets at the same time as the manifold? When the head gaskets go, is it because af a head problem (warped, cracked, etc...) or just crap quality gaskets?

    Your help is greatly appreciated....
  2. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 1000 Posts

    Every water leak on a SBC that I've ever had either came from a radiator, tubing or from around the water pump ... and I've replaced all three before.

    How many total miles do you have on your 96?
  3. 909

    909 New Member

    It has 170k on it. When I got it, it had 136K on it and I replaced the following:
    All fluids, oil, diff front and rear, flushed the radiator, fuel filter, trans fluid and filter, the cap/rotor, wires and plugs.

    About 1 week after owning it, the A/C was not cold so I replaced the O-tube, it had a leaky schrader valve on the high side so I replaced the schrader and cap, also replaced the check ball on the low side, drew a vacuum and refilled to spec. I was also getting a "check wallet light" and pulled the codes which indicated a misfire on the passenger side as well as that bank running rich which means that I changed out the fuel pressure regulator.

    Last summer, the water pump went bad so that's new and I replaced the hoses at that time.

    There is no visable coolant leak from the front of the engine but it's going somewhere. The oil coating the radiator cap isn't a good sign that it's just a coolant leak on the outside of the engine. The fact that the oil isn't frothy or grey is a good sign though but it usually means a head gasket. I just don't know if these heads tend to warp or not. The full gasket set to do both heads and manifold along with the TTY bolts is around $130 but I don't want to just throw money at it if there may be a problem with the heads themselves. This is my wifes primary transpo for her and the kids so any more than a weekend of down time is going to hurt. I can do everything inside of a weekend but i'm wondering if I need to have a new set of heads on tap and just swap everything, or just go after the gaskets.

    Also, something else comes to mind here. When I replaced the coolant on my '94 K1500, I did a rad flush. I inadvertantly flushed out the radiator sealant that the previous owner had added to it when I did this. There was a small pin hole in the radiator once I was done. Thinking that this couldn't be coincidence, I dumped in some sealer and the problem hasn't resurfaced in the past 2 years on the truck. Maybe some rad seal could have been in the system when I replaced the water pump, got flushed out, and now the leak is back.

  4. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 1000 Posts

    Having an internal leak is obviously the hardest to detect. I'd get some more leak blocker and see if that helps. How much water are you losing? How many miles until you have to fillup? If there was a problem, it's only going to get worse with time.
  5. 909

    909 New Member

    It seems to drain the resevoir about every 3k miles or so. Not alot. There is no visable fog coming out of the tail pipe other than what seems to be condensation burn off in the morning. I'll try the sealer and see if that helps it out. I was just hoping that it'd last a bit longer. We are moving and I have a 40x60 shop on the new property that isn't complete yet. One of my first projects at the new building was to pull the trans out of this and fix the oil leak. Then I could do the front and rear seals of the trans at the same time. Looks like i'm going to do the top end gaskets too.

    This pretty much sucks seeing that my non-vortech has an additional 100k miles on it, still makes good power, and has never been towed home.
  6. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    The Vortecs are known to have intake manifold gasket issues. Usually associated with lost coolant. When mine went bad, it was an external leak, and it was easy to locate with a pressure tester (Autozone borrows them out). Seals on the water pump went about the same time, so I ended up doing both. 1st thing I would do if it's using coolant would be to put a pressure tester on it cold, pressure it up, and see if it starts dripping.
  7. smokestack

    smokestack New Member

    Ive heard the same symptoms with a friends vortec..and it was just the intake gasket. Like Mrshorty said ive heard its a common problem with them. From the ones ive had go out the head gaskets will usually make noises and such. Might of just been my luck but in two cars i had head gaskets went bad and they made all kinds of awfull noises.

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