Subject: loss of radiator fluid enternaly
Question: 1990 mitsubishi montero, v6 3.0l I have recentealy replaced both cylinder heads and all gaskets along with the job, the truck is running great but I am looseing about 8-10 oz of radiator fluid a day, I can see no signs of external leakage and I am hopeing there could be another answer to the coolant loss, I seem to think it is leaking out of the intake manifold gasket, the other option is the headgasket itself, is there a way to find out without removeing the cylinder heads again?
Answer: Rodney, Typically if there was a leak in your head gasket you would be able to do a compression test. If your compression is below spec, than your problem could very well be your head gasket.

But typically if your head gasket was leaking, you would be showing some sign of if in your exhaust; such as a sweet smelling white smoke coming out of your tail pipe. If your intake gasket was leaking, that's harder to detect because that coolant may evaporate before gets through your exhaust.

I'd recommend first checking your coolant resouvoir overflow tank to make sure that has a good seal. Next, check all your radiator hoses (upper and lower), including your heater hoses for signs of leaking. You may be leaking fluid onto something hot, which would make the coolant evaporate before it has a chance to touch the ground. Check your intake manifold gasket for any sign of seepage. Finally, get a compression check done on each cylinder. If there was a leak at all from the head gasket, the compression check should indicate that.
Good luck!