i have a 91 f150 4x4 with a 5.0L i recently had to do two water pumps in 4 months, after the second one the timing cover started leaking coolant externally as well as getting lots of moisture in the filler cap.
I figured it was from coolant getting into the oil from the timing cover. Yesterday i changed the t/c gasket and pcv valve (just incase) and it still gets moisture in the filler cap. If i pull the cap or the dipstick it pushes steam out.
The truck does not have overheating issues.
It also gets oil/water mix in the air box.
Could it be a head gasket without heating issues?

 

Think, cause and effect. You have been replacing water pumps, up until that time, no coolant in oil. I would say no problem with head gasket, your getting a leak past the water pump/ timing cover.......a bad leak....Take the truck out of service, drop that oil and hope the coolant hasnt corrupted your bearings yet. redo your water pump, you probably find your leak there. Put her back together and hope for the best, but if you have got that much coolant in your oil, you may have serious engine damage.......Good luck!

 

It was getting moisture in the filler cap periodically before doing the pumps as well.
When i drop the oil no coolant or milky oil comes out. But the inside of the filler cap drips with water when i pull it. And its like moyonaise.
But again the oil comes out clean.

 

In cold weather my truck has moisture under fill cap. Summer time its fine

 

What does the oil on the dipstick look like?, I bet you find "mayonnaise" on it too.

 

Only near the top of the tube, if i dont scrape the inside of the tube on the way out it comes out clean.
it has been fairly cold here, around 0*

 

Little update, took the truck for a 120km trip on tuesday, still mayonaise in filler cap. Took it on a 700+km trip wednesday and halfway through the trip when i stopped for gas i checked and guess what..............................

No mayonaise, not even a sign of moisture.

Could it be condensation from cool temps that needs a really long run to burn off?

 

Keep an eye on the coolant level and oil cond., you may just have lucked out!.............Good luck!

 

Yeah that sounds weird. Good to hear that there are no signs of moisture in there anymore. I have heard of engines getting moisture in them like that before, but they were only being driven very short distances, or used like a yard truck or something like that. You may have had too much built up in there to burn off without an extended trip like you took. I live in the South, we don't get low temps like that.