Coolant Issues

[Bruins04]

Hello all

I have a 2004 GMC Sierra with the 4.3L engine.

My issue seems to be that it's burning coolant.

I have no visible leaks.

Pressure test holds.

My thoughts are that maybe the thermostat is not working correctly?

Any thoughts?

 

Thank you

[txab]

Check closely around the water pump for signs of leakage. Residue from coolant/water mix. WP gaskets are a common leak point. Pressure test it cold and hot if possible

[jaredlucky16]

Intake gaskets

[hzhardy]

If it is going into the combustion chambers you may be able get condensation on a cool object from the exhaust from the steam. This is usually a give away of a head gasket issue. Some time it will blow strait into a water massage and you will never get water in the oil. Also smell your coolant. If it smells like fuel twill confirm a blown head gasket.

[Bruins04]

Thanks all

It's not into the oil, (thank God)

 

Should I smell coolant when hot? (this a new one)

[hzhardy]

It does not matter, just use comments sense while opening the coolant system on a warm engine.

[aflesch]

You need to have a "block test" done. This test that can be performed by any reputable shop and will test for the presence of exhaust gasses in the coolant.

[hzhardy]

You need to have a "block test" done. This test that can be performed by any reputable shop and will test for the presence of exhaust gasses in the coolant.

 

I believe you can buy test strips from the parts store to check your coolant for fuel/exhaust presence, but typically you can smell the fuel byproduct in the coolant from exhaust gasses going into your coolant contaminating it.

 

I just would not want to pay a shop to find the obvious that's all

[txab]

+1 on the strips. They work

[Zembonez]

Another vote for a failed intake gasket. Had this happen on my last 4.3.

[txab]

Another vote for a failed intake gasket. Had this happen on my last 4.3.

 

After re-reading the OP and noticing it is a 4.3 not a 4.8, I'd agree to suspect the intake gaskets

[markw8]

They can leak to the outside without seeing anything on the ground. I had one.

 

Mark

[Bruins04]

Thanks for the input.

[caddytech10]

I too would suspect intake gaskets. I've done plenty of them on 4.3 and 5.7 Vortec engines. It is a very common problem with these engines. A lot of the time they will leak into the lifter valley so you can't see the leak externally. Usually it's not a bad enough leak to milkshake the oil. Only in real severe cases have I seen that.