I had a guy come by today asking about Gen-III motors eating coolant. He has a friend with a 6.0L LQ4 truck. He only drives it a little each week, to and from the store mostly. However, he also hauls his antique tractors with it. He has noticed that his motor is eating a little coolant, maybe a pint-quart a week. No puddles.

Is anybody else's motors eating coolant. I have beaten the p!ss out of many 5.3L Iron and Aluminum motors, Iron and aluminum 6.0's and have not had this problem before. Just curios to see what others have experienced.

THNX

 

weird... coolant leaving without puddles is a symptom of a leaking headgasket

 

Mine has gone down about an inch or so since I filled it during my last cam-swap this past August...

That raised a flag with me, but I'm not too concerned right now.

 

That's whay I thought, but he's not losing as much coolant as you would think if the head gasket is the problem, and he has not abnormal cooing system pressure issues, another good sign of HG problems. I wonder if his water pump is going. I had one going on my LT1 once, and it never left a puddle, but I sometimes smelled coolant. It was weeping out the weep hole at the bottom of the casting, and not enough to puddle, it seems it would evaporate pretty quickly..

 

Mine did it for about a month, then it quit and had no signs of leaking.

 

There is a TSB out on the coolant cap not sealing. Mine did the same thing until I replaced the cap with a Stant one.

 

Tsb??

 

Technical Service BUlletin.

 

TSB

Engine Runs Hot, Overheats, Loss of Coolant (Polish Filler Neck/Replace Radiator Cap) #00-06-02-001 - (Jan 5, 2000)
Engine Running Hot, Overheating and/or Loss of Coolant (Polish Radiator Filler Neck and Replace Radiator Cap)
1999-2000 Passenger Cars and Trucks

with Composite Radiator End Tank

Condition
Some customers may comment on one or more of the following conditions:

Engine running hot
Engine overheating, and/or
Loss of coolant/low coolant message
Cause
The radiator filler neck may have an imperfection in the sealing surface.

Correction

Important
DO NOT REPLACE THE RADIATOR.


Using a piece of 400 grit wet/dry sandpaper backed with a flat piece of wood, polish the filler neck sealing surface using a circular motion.

Replace the radiator pressure cap with a cap of the same part number as shown in the GM Service Parts Catalog.

 

if you still suspect head gaskets, there are a few simple things you can do.

hook up a scantool and watch misfire counts at cold startup. sometimes the coolant in a cylinder will be enough to cause misfire at startup, but not enough to set the DTC P0300 (misfire detected)

another thing. most auto parts has a kit to test the engine coolant for traces of combustion gasses in the coolant system.