1999 Tahoe, 5.7 engine, 250,000 miles.

Been losing coolant for a while, with no sign of an external leak. I was told it was likely the intake gasket leaking....common, I understand....so I have just been adding coolant.

Now, its showing up more noticeably on the dipstick and in the pan. How do I determine if its the intake gasket or a blown head gasket?

Thanks for any and all help.

 

Compression check and have it done right away. Coolant in the oil will eat your bearings up if it hasn't already done so.

 

Most likely the intake. Head Gaskets do not fail unless the engine is severely overheated.

 

Head gasket would probably cause some running problems too.

 

Thanks for the helpful comments.

Being as:
Its a 250,000 mile engine.
I have run it for a long time knowing coolant was leaking internally.
I had a brief overheat episode a while back when that heater hose fitting on the manifold rotted and blew off.
It has recently started missing badly when cold, which I'm told may be a cracked head (see overheat above)
And, the dipstick is milky now constantly, also a recent development,

I have decided to just put an engine in her and be done with it. Lucked up and found one with 79,000 miles on it, and a warranty. The main deciding factor for me was the mileage and the unknown of how much wear I had caused by running it with coolant in the oil for an extended period. If the head turns out to be cracked, it would be the only viable decision.

Thanks again for the help.