1990 f-250 4x4. 7.3 diesal / pumping water out radiator cap or overflow/changed thermostat and cap/no diff /no coolant in oil no oil in coolant runs smooth/no water detectable in exaust/ slight white smoke on start as always/ maintains pressure in radiator for days/ have bled air from block by pulling heater hose anfilling to coolant runs out/ any ideas /oh yes used the test kit for hydros in radiator color went only slightly to blue green/ rather then brilliant blue/

 

Sounds like the beginning of a break of the head gasket at the intake side of the cylinder.
That is the reason for the blow back through the radiator.
If it starts to run hot or blow white smoke out of the exhaust then the break is starting to widen.

You can drive the truck for a long time if you take it easy and watch the water/temp levels.

 

I'm not a big fan of the liquid head gasket stuff

 

it is best just to fix it right.

 

Dont use the liquid stuff that claims to fix head gasket and other leaks.. my bro-in law used it for his leaking heater core... by time we were done it cost him a water pump, radiator and heater core.. plugged everything up, still gets hot with big loads, never did before.

 

if a head gasket gets bad enough to cause a lot of white smoke out of the tailpipe would that mean that probably mean there was some coolant in the oil?

 

I would definately say possible, not to mention the strong possiblility of hydro-locking.

 

time to change the oil!

 

hydro lock is what???? sori but dont know diesal engines and way old to learn hihi but any help is gud even if its wrong its a learning experiance thanks

 

oh it pumps water out too fast to go anyplace or to try the head gasket repair stuff /just wanna good iundication its the head gasket and not somthing else