loosing coolant

2000 GMC SIERRA

168,000 MILES • V8 • 2WD • AUTOMATIC

ALJOHNSONII

MEMBER
3 POSTS

I've been loosing coolant when you take the oil cap off there is a yellow milky subject around the cap. there is no indication of water in the oil. could it be the intake gasket or something major like head gasket, there's no water leaking out of the exhaust and no misfires.

Nov 19, 2008 at 7:54 AM

SQM

✓Experienced Mechanic
6,383 POSTS

Hello,

The yellow milky residue indicates there is condensation in the oil. It could be due to a head gasket leak.
Best course of action would be to perform a head gasket leak test. There are few different ways to check. One of them is using a head gasket leak test kit. This test uses a chemical that detects any combustion gases in the coolant. It can typically be purchased at your local auto parts store.

Here is a helpful video:

https://youtu.be/5zpNjYmmiYY

Since you are losing coolant, it will be a good idea to do a cooling system pressure test. This can help you determine any leak.

https://www.2carpros.com/articles/radiator-pressure-test

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

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