Have a 2000 Chevy Silverado Z71 Ext Cab with the 5.3 L in it. Bought it new in late 1999. Currently has 142000 miles on it and have been noticing that it is starting to each antifreeze. Anybody know of problematic issues with this vintage truck/engine/........? Definitely not an external leak. Have moisture on my oil cap. Used about 6 cups of water over a 2100 mile period. Thoughts?

 

Sounds like a blown head gasket. Do a compression test on each cylinder. Look at your exhaust tip after its warmed up and see if you notice an antifreeze odor. While its running look at the oil dipstick and see what it looks like.

 

Thanks Ruff. Pulled the plugs last night. All looked ok. Nothing major with the plugs. Drained part of the cold crankcase oil and everything looked normal. No seperation of oil and water as far as I could tell. No white smoke out the exhaust. Will try the compression check tonight.

 

Another problem with these motors is the intake gaskets, they tend to blow and leak some antifreeze. Either into the intake or on top of the heads and intake valley. It would evaporate it before you saw puddling. I know the 5.7L Vortec's do it a lot. Mine is doing it right now, I just haven't had a chance to change the gasket out.

Also make sure you have a 5.3L, not a 5.7L. It is a common mistake. You should see it on a tag in the engine bay. Or you could run your vin and see all of what your truck has.

Well good luck and when you find the problem let us know what it was.

 

Got red or green antifreeze in it? Red bad; Green good. Red is acidic...

 

WHAT ACID IS BAD FOR YOUR ENGINE? WHO SAYS THAT!! I am just kidding. For all of the other people out there, ACID IS BAD FOR YOU AND YOUR ENGINE!!

 

What you could also do Slim is have a radiator shop put a pressure nozzle on it and add some PSI and see if it squirts out anywhere. Like putting 60 PSI in a tire and putting it in water to see a small leak.

 

I bet it is the waterpump weepholes are seaping while going down the road. After driving a while does teh hoses have pressure on them after you stop and open the hood? Come to think of it my grandmothers 2000 model Chevy Silverado with a 5.3 is doing the same thing. She says it is not bad enough to worry about, but I am about to start looking into it. Let me know what you discover so I can have an idea too.

 

Well when the weep holes start leaking, that means the the seal to the bearings in the water pump are busted and its fixing to seize up cuz the antifreeze is soaking up the bearings. Remember how the belt sounds when you get antifreeze on it?? Well thats what happens. So the weep holes are made to fore warn of a water pump lock up. Other wise in the old days we would throw a belt and wonder why without checking the pulleys!! LOL

 

The '99 and up gaskets don't have a tendency to leak. Not being argumentative with you gpet - just letting the original poster know it's almost definitely not the problem.