ANTIFREEZE DISAPPEARING - NO VISIBLE LEAKS - 1989 GMC Sierra

HI. This issue has many causes. i will list the most common causes below.

Coolant consumption::: Possible causes______


1. Check the head gaskets. The gasket may be leaking.
2. Check The Intake Manifold Gasket. This gasket may be leaking, worn, or damaged
3. Check the cylinder head for worn or scorn cylinder block.(This will require total breakdown of the engine)

4. Check the water pump seal for leaks as well.

Now that we have covered the basic check points for coolant consumption, i would advise to concentrate on the head gaskets if there are no apparent leaks on or around the engine itself. If the head gaskets are worn, the leak can be introduced to the engine internally, causing the engine to burn off the coolant. this is noticeable by removing the oil cap, after a hard drive. you Will notice steam that will escape the head as soon as you remove the cap. If this is the case, your problem will be with a failed head gasket.

IN a severe case, you will notice white plums of smoke escaping from the tail pipe during acceleration.

It could be a very slight leak or it could be a bad head gasket or even a cracked head.. If the engine has ever over heated - that could eaily damage the head gasket or head.. You need to get a compression test done to diagnose the problem..

Best of luck !!