Hey everyone. Been a while since I posted since I have been on my internship working 72 hours a week. Here it goes:

I have been monitoring my fluid levels on the truck and I have noticed that my overflow reservoir level has been very slowly (over a period over a couple months) going down and now it is around the "ADD" mark. My intake gasket is fine, I notice no white stuff in the oil nor increase in oil level (I am changing the oil today and I am hoping that that fact holds, I do not smell anything in the vents nor detect any leaks from the heater core, my hoses were replaced about 4 years ago and are still looking like new, water pump was replaced in December and I can't find anything wrong with anything else on the cooling system. Where could this antifreeze be going? The truck has been driving and being parked in 80-90+ degree weather over the past few weeks, so not sure what that could have to do with it. Thanks

Forgot to mention, radiator is full and some antifreeze comes out when I open the cap.

 

Run a coolant pressure check.

 

Can't really do that this week. Anything else I can check before I can do that?

By the way, the oil was dark brown/black in the pan. No white at all. It is like it vanished. I added half a gallon of 50/50 premix earlier to fill the bottle to about an inch under the overflow tube.

 

when mine was doing that it was the water pump. it only leaks while the engine is running so the drip was just getting blown away with the fan. pressure tested it and found it

 

Water pump was replaced in December and the weep hole is completely dry. I looked at it and it wasn't leaking even with it running.

This may be a dumb question, but does antifreeze evaporate from the expansion tank?

 

No, it does not. The only way it disappears is from a leak somewhere in the system.

 

I've heard of head gaskets making it possible to lose coolant out the exhaust, but I've never taken the heads off before to see how that works.

 

If its coming out of the exhuast you will see white smoke or smell coolant in the exhaust.

 

There is none. I barely see any smoke at all coming out of the tailpipe and that is from condensation on startup. There isn't any white smoke or coolant smell as far as I can tell.

Are head gaskets a common thing to fail on 4.3s? I realize intake gaskets are common, but I don't let this thing overheat.

 

Head gaskets failure is pretty rare on these motors. Its usually if you let it over heat and the heads get warped that its an issue. How old is your radiator cap? You might try throwing a new one on.