1998 GMC C1500 losing coolant

CROS0102

MEMBER
1998 GMC C1500
V8
4WD
AUTOMATIC
170,000 MILES

Ive been losing coolant everytime ive drove my truck. Theres no sign of leakage anywhere. No coolant in oil. No oil in coolant no over heating. All hoses are good and no sign of the water pump failin or leaking. The intake manifold shows no sign of leaking, I put a pressure test on it and over 8 hours no movment in pressure, engine was completly cold. There is a smell of it burning while running but theres no white steam or smoke. Just alittle of white smoke out the tailpipe and the usualy looking condensation.

is it possible for the coolant port or exhaust port to blow through to the other in the head and if it is possible what actions should I take. Will there be more damage to come.

3 Replies

PEAR69

MECHANIC
1,482 POSTS

The lower intake gasket is probably leaking coolant. The coolant is probably leaking onto the exhaust or a hot part of the engine -- this is probably why you cannot see the leak but you can smell it. This is a common problem with these engines. Run the engine up to temperature for 20 minutes or so and look for a coolant leak by smelling your way to it. I know it sounds a little crazy but it works.

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Monday, April 27th, 2009 AT 9:56 PM

CROS0102

MEMBER
2 POSTS

I just changed my lower intake gasket. Because they were leaking before inbetween the intake manifold and where in stis on the head. Now theres no leak to be found.

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Tuesday, April 28th, 2009 AT 9:01 PM

PEAR69

MECHANIC
1,482 POSTS

If the coolant were leaking into the exhaust port the exhaust would be smoking and you would also be able to tell by pulling the spark plugs and looking for an unusually clean plug. The engine would eventually began to mis-fire real bad.
If you recently changed the LOWER intake gaskets--there may be some residual coolant somewhere on the engine that burns off when it gets hot -- and -- the loss of coolant level may stem from not filling the system completely when you changed the gaskets.
Check where the the heater core hose plugs into the right front of the lower intake. Sometimes just a little coolant will leak there.
Double and triple check the oil for coolant. It is easy to over tighten the lower intake gasket causing the gasket to fail prematurely.
If all fails to find the leak, put a bottle of Barsleak Gold, or conventional Barsleak in the radiator. The ingredient in this sealer (ground up ginger root and walnut shells) seals small leaks when it flows into the leak and is exposed to air - outside of the leak. It will not harm the system in any way. It also works on small head gasket leaks.

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Tuesday, April 28th, 2009 AT 9:38 PM