just bought a 99 f250 xlt crewcab with the 7.3 automatic with 252000 miles on it, person i bought it from said his mechanic thinks it has a cracked head. he put 12,800 in repairs in the last two years- new tranny, transfer case, hubs, spindles, water pump, alternator, heads, hoses and tons of other stuff the dealer did. the truck is in great condition, just needs cleaned up. here are the symptoms; when i test drove it, i rode it hard and fast trying everything out making sure 4x4 worked and all that for about 15 minutes, when pulled into the lot the reservoir for the coolant had fluid spewing out from the cap. after buying the truck (
$4700) i drove it 100 miles home and it never leaked a drop, and now i haven't been able to get it to do it again. the heater will blow cold even when the engine temp gauge is in the middle of norm and then it will blow hot for a couple of minutes and go cold, then hot, then cold. i checked the upper rad hose today with engine running and warm, heater blowing cold, upper hose and heater hoses were cold, pinched off hose for a few seconds and i could feel pressure surging when released. chekced the fan clutch with engine warm and doesn't have much resistance to spin by hand, so I'm going to change that, had reservoir cap pressure tested 3 times, 1 time it dropped to 14 psi, the other two it relieved at 16 and maintained, so i put a new cap on it and drove it hard again, it didn't leak, but i still had the heater blow hot, then cold. any ideas on what to check or look for, anyone know of a good test kit to check for combustible gases in the coolant. thanks in advanced for the help, i hope i got a good deal.