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  1. #61

    Default Coolant Leak

    I said in my last post that I fixed it. It was infact the HEAD. I replaced the left side and have not had any problems. If you read all the post you will see that many including me have had all the pressure tests done and it had shown nothing. With the hairline cracks in the heads you can not diagnose the problem. All test come back ok. When I took my truck in to the Chevy garage, I told them I wanted it daignoised and when they called me to tell me they could not find anything, I told them to take the heads off and then look for a hairline crack. They told me I was nuts. Well they thought different after doing what I said. The left head had 2 hairline cracks near the drain holes. I put a head on the left side and have had no problems.

  2. #62

    Default

    its not on your head gasket About all I can suggest at this point is to get the cooling system pressure tested. That will reveal where the leak is coming from. Since the filler neck is part of the thermostat housing, it could be something as simple as a bad cap. A pressure test will tell for sure.

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  3. #63

    Default Coolant leak fixed

    This is in reply to the pervious post

    I never said in my last post that it was the head gasket, please read the post before you reply.

    I said it was my HEAD on the left side. I also stated that the garage had done the pressure test and found nothing.

    I have fixed this problem by REPLACEING THE HEAD on the left side. the head had a hairline crack in it (which is a known problem with the engine) that is not detected with the pressure test.

  4. #64

    Default

    Coolant leaks are peculiar. When they leak you usually smell it. Remember this is a pressurized system at boiling temperatures. Coolant modifies the boiling point (I'm a chemist, hang in there until the slam dunk). Under pressure, there's no boiling. What happens when you open the cap? You dropped the pressure to atmospheric - where the hot coolant can boil and you make a geyser. Don't try this at home.

    So. When you have a leak it instantly vaporizes as the coolant hits the air. And it wont leak until you are hot. You never see it but you smell it. Clean up the area where it might leak with soap and water. Soon your leak will show up as white residue as trace proof of the leak.

    There is a flourescence in yellow coolant. Or you can add dye. You can heat up the engine and turn off the lights, get out the blue light or UV light and look for coolant. Typical leaks are at the radiator cap crimps, bung valve, hose fittings, heater core, water pump and 'stat housing. Look at the hose at the clamps - they degrade fast right there. I haven't looked at my new rtruck radiator but my last truck radiator had plastic caps crimped to the core, where two replacements leaked.

    Internal leaks at the head gasket or cracked head show up in the oil like you said, but in the tranny cooler, it would be in the transmission fluid.

    Good luck

  5. #65

    Default 2001 4.3L v6 engine with coolent leak

    Quote Originally Posted by Rumpamuro View Post
    Well glad you found the problem, if any of these trucks were 4.3 v6s than i coulda explained to you exactly what was wrong with the coolant, but the v8s are usually good with coolant leaks. now i know and so do many other concerned truck owners.

    I have a 2001 4.3L v6 engine with a coolent leak. it comes down the back of the engine and leaks after I stop. every couple of months I have a low coolant message. I have been to one mechanic and he told me it was a gasket and the thermostat and want to charge more than a dealership to fix it. So far I drive it and can smell the coolant when I stop. Engine is not over heating and drips some coolent over night. Water pump is ok no leaks there and so far can't find or see another other spot its leaking from. Do you have any suggestions?

  6. #66

    Default coolant leak - update 18 months later

    Just a follow up on my coolant woes from the summer of 2009 that I posted about here. I had put the GM-branded sealant tabs (crushed walnut shells?) into my coolant and that stopped the leakage. 18 months later, up to 206,000 on the odometer, towed a trailer across the US twice, and it hasn't had any more problems. I've lost a *little* amount of coolant, but I've never had to top it off. I still have no idea as to the root cause, if I have some leaky gasked, hairline crack, or what.

    However, the original fuel pump finally went out on me last weekend (206k miles on it). I don't know why people make such a big deal out of replacing it, I was able to do it in two afternoons all by myself, even with dropping the tank. Trying to pump out as much gas as possible was by far the most work (got it down to 1/8th tank), after that it was basically a couple sets of fuel lines and two straps holding the tank up. I had no idea how heavy and unwieldy the tank would be, turned out to be like 20-30 pounds even with the leftover gas in it.

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