My daughter has a 98 f-150 STX Style side 4.6 auto with 150,000 miles on it, The problem we have having is its blowing antifreeze out of the coolant jug and the temp gauge will all of a sudden jump up to max hot then come back to normal all within a few seconds. it had a leak behind the intake and i bought some of that Bars leak stuff , the Bars leak had little shinny particles in it, and when i checked the oil i saw the small shinny particles on the dip stick!! does that mean i have a blown head gasket?? also the top hose seema to have alot of pressure in it. i changed the thermostat a couple days ago but no help.. Thanks for the help dave

 

It has most of the signs of a blown head-gasket.

I know when I was getting presser in the cooling system ,my gasket was blown.

Phil

 

X2 ....
compression check will probably verify

 

iam going to agree with blown head gasket....from your post it looks like you have coolant in your oil? do you have oil in the coolant overflow box?

 

Those are exactly the same symptoms mine had when the gasket blew. A hydrocarbon test will verify it. Also if I was you change both the left and right gaskets while you have the engine disassembled even if you think one side is ok. Good luck