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My '04 Silverado and my brother-in-law's '00 Suburban both have 5.3s and both have magical disappearing engine coolant. No coolant leaks in hoses, radiators, coolant tanks, or water pump. Has anyone heard of or seen this problem before. Are there any known coolant passage flaws cast in these cylinder heads. any help or info will be greatly appreciated.
Tommy T.
hows the oil look?
I just changed the oil and it showed no signs of coolant contamination. However there was sludge in the oil filter probably due to the three times it got hot. I checked the plugs also and they looked normal.
I have worked on a few 5.3s that the wter pump gasket was seeping and it would not make it to the floor to show signs of leaking.
I guess the water pump only leaks when its hot and or under high rpm conditions?
I ended up buying a pressure tester from Napa for my 02 avalanche. The coolant loss was driving me crazy, nothing would show up while idling or parked overnight. It ended up being the back of the water pump, where the impeller fits flush against the housing. It only did it under load while you driving. After buying the adapter and presurzing the system it leaked like a sieve.
They were leaking and the fluid would dissapate before it made it to the ground. Just look for spots where coolant has been running down.
New pump or can it be resealed?
New pump
Thanks, I'll double check with an overnight pressure test and go from there.
i just replaced mine in the SS. the gaskets were leaking slightly, and id only see a couple drops on the ground,, but the whole underside of the engine was soaked, but not yet dripping. .my coolant wouldnt go low.. so i just replaced it.. if you need a water pump for an engine, or if a 6.0 would fit, hit me up.. ill sell u my extra one for what I paid for it.
Umm....the 04 might have head issues. Pull a valve cover and look in there as you will likely not see it in the drained oil. Where is Steve?
Water pump to block gaskets are super common and only leak when COLD after sitting all night. Since the Dexcool has so much alcohol in it it evaporates and dries up off the floor and engine block and leaves no puddle in many cases. Look for pecker tracks on the front of the block, usually on the RH side of the engine, down towards the cross-pan harness.
HAHAHA!!! I am not laughing AT Steve, just the reference. I will bet that it is the dreaded Castech 706 head.Quote:
Originally Posted by GasGuzzler
Dude--don't mess with anything else--replace the heads. Trust me. Also, while you have the heads off, clean the tops of the pistons cause they will more than likely be pretty gross.
what is wrong with the 04 5.3's with 706 heads???? i would like to know.
Google Castech Heads and see what you get.
What would you use to clean the pistons? Think I remember someone talking about using Kerosene.Quote:
Originally Posted by txarkitekt
they had a problem with the casting and the coolant would seep through the pores of the aluminum...and you would have yellow oil/coolant build up all in that valve cover... i replaced 2 sets when i was a tech at gm.. even if one side is leaking we would replace both....
Ooops and Steve's was the only one I ever saw.Quote:
Originally Posted by MYSHTBX
thanks for the info. we don't do alot of gm where i work and i haven't heard about the 706 heads until yesterday. so looks like i need to start another parts list.
We've had 3 trucks with Castech heads in the last week, one of my motors had them
the ones we had were on tahoes