I have a 1989 Ram W-250 with the 360 in it. The motor runs good for the most part, but after longer trips i notice the antifreeze boils up back into the reservoir and out the overflow... It's done this since i got it, i put a new waterpump, thermostat, clutch fan, fresh fluid, and it still happens. The temp gauge never gets over half, anyone run into this before, any ideas? Only thing i can think of yet is headgasket, but really hopin this is not he case!

 

New thermostats can still be bad. Maybe try it without one?

 

Join the club. My truck has done this since it rolled off the showroom floor. The dealership and I would like to know if you solve this problem because they sure couldn't find the problem and after 23 years I haven't either. I live in a mountainous region and mine does this every time I come up the mountain and stop at the top. I have done everything I could think of. New radiator, radiator cap, thermostat, hoses, water pump, heater core, fan clutch, fan blades, and even a set of electrical fans. The truck never overheats while running but shut it off after any loading and the engine temp soars. I don't like it but i have accepted it as normal for my truck. Good luck.

 

Is it possible the radiator cap is letting go at a lower pressure than it should?

 

Maybe I misread what you mean so please clarify. Does the engine temp rise when it is doing this? Are you having to add coolant?

 

No, the engine temp gauge reads normal, and yeh i gotta add coolant because it drains outta the overflow on the reservoir. Thanks for the replies here, i appreciate them!!

 

Then to me it sounds like a defective cap (easy fix) OR a head gasket leak, leaking compression into a water jacket (not so easy fix), but a cap's probably $10 or so.

 

I'll for sure try the radiator cap, if it is the gasket that would be my luck lol

 

If the coolant is not being sucked back into the radiator as it cools It is probably the cap. If the cap doesn't fix it a pressure test will tell the story about the head gasket or a cracked cylinder/head.