When are you overheating? Stoplight, highway, etc.
A couple of things to check-
- air in system?
- are you still running the thermal clutch fan (stock)? If so, this may be bad. Had the same problem on my Wagoneer at one point. Even though the fan "tested" fine, it wasn't. New fan dramatically reduced my engine temps.
no. Is it possible to have a cracked head and not have fluids swapping. Such as water in the oil and so on?
Yes it is possible and likely a cracked head will not dump coolant into the oil.
But a cracked head will not overheat the engine in 3 minutes from cold. It will over pressure the cooling system.
my first guess is either the wrong head gasket or it is on backwards. that's about the only thing that could do it in 3 minutes. Even if the water pump was dead (no belt) it would take about 8 to 10 minutes to get to over heat from cold.
1981 Jeep CJ7 4.0 HO, AX-15, D300, D30, D44, SOA
1977 Chevrolet C/10 step side 454 TH400 3.73 posi
Well put block sealer in and let set for 24 hrs. Put new bottom hose/w spring in today.......Started it up burped the system and all was good for about 2 hrs....and then...... same old crap started heating up fast. Head gasket on right and it was overhauled before I bought the jeep about two months ago.....Any ideas where to get another head for a 79 258 AMC inline 6 in AZ:
the fact that block sealer had an effect might indicate that the head is cracked and pumping compression into the cooling system giving you the air pocket. if you have a coolant system pressure tester put it on the radiator cold and start the motor and see if it indicates static pressure simply from starting the motor. another way would be to lower the coolant level in the top tank and run the motor til the thermostat opens and see if the temp stabilizes without overheating, it cant build system pressure without the cap. uh, dont get burned/scalded if it burps when the stat opens.