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Suburban 5.3L coolant leak into engine

10 messages,  Last post on Feb 27, 2009 at 5:04 PM

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#1 of 10 Suburban 5.3L coolant leak into engine by daves67 Mar 05, 2007 (2:50 pm)
I'm having a difficult time solving an internal leak of antifreeze into the top of the engine. It is getting into the valve train and apparently into the cylinders as well, but never gets into the oil pan. It uses about 1 gallon a week with no external leaks. Oil fill and PCV cover inlets are full of white/brown mix of water and oil. I've already changed the head gaskets once, about 6 months ago- they were leaking. Milled the heads flat, etc. Thought the problem was fixed but it came back in about 2 months. Any ideas? Replies to this message: arrie (Mar 18, 2007 9:24 am) daves67 (Mar 18, 2007 6:30 pm) arrie (Mar 24, 2007 6:30 pm) immrchevvy (Mar 27, 2007 6:13 am)
#2 of 10 Re: Suburban 5.3L coolant leak into engine [daves67] by arrie Mar 18, 2007 (9:24 am)
Replying to: daves67 (Mar 05, 2007 2:50 pm) Hi daves67,   It sounds like changing head gaskets fixed the problem for two months but the problem then came back, right?   Have you re-torqued your head mounting bolts after gasket change?   Arrie Replies to this message: daves67 (Mar 18, 2007 6:30 pm) arrie (Mar 24, 2007 6:30 pm)
#3 of 10 Re: Suburban 5.3L coolant leak into engine [arrie] by daves67 Mar 18, 2007 (6:30 pm)
Replying to: arrie (Mar 18, 2007 9:24 am) Hi Arrie, No, never did that. We did end up having the radiator rodded out, it was clogged with the GM coolant - the engine got up around 240 deg. before we had it fixed. Of course it happened after the new gaskets. I'm afraid that with 140K now on the motor, it may be best to just go through it, but there is no sign of water in the bottom end and the oil pressure is still around 45 lbs. Will the stretch bolts handle a retorque? Replies to this message: arrie (Mar 24, 2007 6:30 pm)
#4 of 10 Re: Suburban 5.3L coolant leak into engine [daves67] by arrie Mar 24, 2007 (6:30 pm)
Replying to: daves67 (Mar 18, 2007 6:30 pm) Hi daves67,   I'm not sure what you mean by 'stretch bolt' but what ever the bolt is it will handle the re-torquing. Re-torquing is sometimes needed for head bolts because the new gasket settles a little bit. This used to be a normal procedure and I'm quite sure it still is for some car engines. Re-torquing the head bolts simply means tightening them back to the torque they were set to when the head gaskets were changed. This does not increase bolt stress.   Arrie
#5 of 10 I had the same problem... by tivy Mar 24, 2007 (6:56 pm)
I had the exact same thing happen. I put in a bottle of Bar’s leak, which I think comes installed form the factory, and 50,000 miles later all is still well. I now think I could have done that in the first place and never changed the head gaskets. Replies to this message: bena8837 (Feb 08, 2008 7:22 am) kiawah (Feb 08, 2008 2:35 pm)
#6 of 10 Re: Suburban 5.3L coolant leak into engine [daves67] by immrchevvy Mar 27, 2007 (6:13 am)
Replying to: daves67 (Mar 05, 2007 2:50 pm) I am the parts department manager for a new car dealer in Virginia. Recently we had a 99 Sliverado with the same problem. It had the 4.8 liter motor, but is basically the same as the 5.3. There is an issue with some of these motors, cracks develop in the head underneath the valve cover and coolant runs out of these cracks and down the oil drain ports in the head, straight down to the oil pan. GM is doing nothing about this. The best fix is a new wngine, which is what we did. New heads are around $1100 each, and a new motor costs around $3000 (new Goodwrench motor). Alldata has more info on this if you have access. You can remove the valve covers and see where the coolant is running down the bottom of the head to the drains, it is clean there. If you pressurize the cooling system with the valve covers off, you may even be able to see it leaking. Sorry for the bad news:-(
#8 of 10 01 Chevy Suburban loosing coolant by bena8837 Feb 08, 2008 (7:22 am)
Replying to: tivy (Mar 24, 2007 6:56 pm) 2001 Chevy Suburban with 5.3 with close to 100,000 miles that is loosing coolant and can not find leak. Is anyone else having or had this problem. It's not loosing a whole lot but it is. There is no water in the oil. Replies to this message: kiawah (Feb 08, 2008 2:35 pm)
#9 of 10 Re: 01 Chevy Suburban loosing coolant [bena8837] by kiawah Feb 08, 2008 (2:35 pm)
Replying to: bena8837 (Feb 08, 2008 7:22 am) Well if it is leaving, it is either leaking on the ground, or into the passenger compartment (as in a heater core leak), or into the engine oil, or into the intake manifold. Into the intake manifold would then be spit out the exhaust and typically you notice it with white smoke (moisture) after the car has warmed up. The real concern is that you can ruin your cat converter, which is a costly problem.
#10 of 10 anti-freeze in the oil!! by 38370monte Feb 27, 2009 (5:04 pm)
350 engine what about the plastic intake? any one have any input on that

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