25k on total engine rebuild 88 5.8 losing coolant somewhere suspect water pump shaft thought i seen a drop there. Pump was replaced 25k ago at rebuild new radiator, cap and thermostat and hoses bought the nice ford blue radiator hose set. Replaced overflow windshield wiper container. I was a gallon down when i twisted rad cap to safety position it purged some fluid then a lot of air pressure. I topped everything off including overflow container. A week later thought i should check after running truck a few minutes. Definitely not enough time to open thermostat. Overflow empty cracked rad cap cold antifreeze gushed out then a lot of air pressure.
i borrowed a snap on rad pressure kit what is a safe pressure psi? To test was thinking what rad cap is rated for

 

where is all the air pressure coming from. Head gasket? Just did oil change 275 miles ago now a qt. Low both front and rear mains are leaking. Not happy

 

Fill the radiator with a cold engine.......... Start the motor ........ Let it sit there and run for 30 minutes with the radiator cap removed.........

Are you seeing air bubbles come out of the neck on the radiator ?


Hobo

 

You ran the engine for a few minutes, but as you say not enough to open the thermostat. As soon as you start the engine, the engine starts producing heat from the burning gas. Even though not enough heat to open the thermostat, the heat that the engine did produce would pressurize and work to the radiator via the bottom radiator hose. That is my take on that, you would have pressure in this situation even without a leaky head gasket.

You are eluding to a bad head gasket which you may not or may possibly have. Sorry about the leaky oil seals, where did you get the engine?

 

Still losing coolant. Engine rebuilt by austen-jordan grand rapids mi.
i tried getting a crate jasper i believe 350 hp they said no go. Even tried through another installer and they told them we already told this guy no go wont work. This back 2005, because speed density or carb motor cant remember.

So this 88. Xlt f250 4x4 5.8 been sitting behind shady car lot for years i stop in and he says rebuilding motor now wrist pin came out. Hung out at his shop before buying.
I did buy for 3k
To tow camper .
i drove around town highway 500 miles to break in motor before camping trip.
50 miles into trip knocking pull into friends house drain and add 2 qts. Lucus. Continue to silver lake sand dunes. Drive the living **** out of this motor as im not happy.
make it back home pull motor send to austen-jordan
They say wrist pin again
Just fix that? No everything new sealed power pistons, new cam for sd new rods, fuel rail, air pump, air injections, all external parts fuel injectors water pump thermostat ford racing valve covers accel dizzy accel coil heddman short headers. And and it runs like crap. Absolute from headers burning sp wires
oh yea
Started motor opened rad cap cold shows fluid to top of cap overflow bottle is empty
As engine warm some coolant overflows neck i use a cup to recover dump into overflow then add to rad as well . so kinda up and down a. Little maybe 16 oz. Did see some bubbles in the beginning thinking head gas but they stopped and never started again. When i shut engine down rad was full and overflow were both full . when i checked cold overflow bottle empty

 

I would cycle it like that a few more times (cold / hot / cold) over a couple of days to make sure all of the air is out of the cooling sytem.

Hobo