Over heating after 20 min

Got an 86 B2000 after 20 min or so it over heats. All new gaskets, thermostat, and radiator cleaned and cap testet. Iam not running a heater so i could take out the thermostat. And i noticed that the fan on these pull air from thr radiator. Any one turn the fan the other way or put an aftermarket one on so the fan blows on the radiator to cool it. Truck runs good otherwise no coolent in the oil or anything for posible crack or warp in the head.

Iam not running a fan shroud either.

Mine did the same the exact same thing and turned out to be a cracked head. I replaced the head and was fine ever the next couple years untill the motor is giving out, going to rebuild or replace it now and keep the good head just incase this happens again. They are know for blown heads FYI.

John

check to see if the water jackets flow. i blew an engine because my water jackets had been clogged and i never knew it.

No fan shroud isn't helping but shouldn't cause an overheat after 20 min. If you run the motor with the rad cap off is there bubbles in the coolant? If there is that often indicates a cracked head. Is your gauge reading accurate?

I have had the same thing happen to me on my Mazda and other cars for that matter. Most of the time bleeding all of the air out of the cooling system has fixed my issue. Hopefully this helps

I bought a cooling fan today and i will try that. with the body drop the fan is a lot higher on the radiator and without a shroud i don't think it was cooling very well. no it does not bubble with the cap off. my temp gage works.

20 mins of driving? or idling?

You said it was Body Dropped right? With this said is the motor Higher then the Radiator? Like in one post above about bleeding the air out the line will be your issue if the motor is Higher then the radiator. And if it was a blown head I believe you would be able to tell it other then just running hot.

Also if you removed the thermostat, put it back in! Without the thermostat in the water neck to restrict flow, coolant circulates through the radiator TOO FAST, it doesnt have enough of a chance to cool off before entering the motor again. Also check out the water pump, the fins on the impeller inside might be so corroded that its not moving enough coolant around. Might also be time to go to a junkyard with a tape measure and grab an electric fan and shroud out of a car thatll fit your mazdas radiator. older ford taurus fans fit pretty nice on 4cyl toyota and isuzu radiators itd probably be nice for a mazda too