Cooling System Problem

[wxman]

While driving my 1989 (first gen) truck a few days ago, I noticed that the heater wasn't producing any heat at all. Shortly afterward, the temperature gauge climbed almost to "H" (i. e. , much higher than it usually runs). I pulled into a gas station and opened the hood. Coolant was overflowing from the coolant reservoir and the radiator was stone cold. I eventually had to be towed home.



We've since changed out the thermostat thinking that it was preventing coolant from cirulating through the radiator. However, that hasn't solved the problem. It appears that the water pump is functioning OK. It also appears that the coolant is being forced into the overflow reservoir instead of the block and/or radiator, and eventually even overflows the reservoir when we run the truck.



Does anyone have any idea what this could be or what to look for?

 

[Lil' Dog]

I said pardon??...

Oh boy... I had an 89 but the thermostat was the problem without any overflow symptoms.



Overflow is a symptom of (gulp ) either a head gasket leak or a problem with the early series 6BT's, cracked head. The large 9mm injector holes are a sore spot for these trucks if you juice em alot. Now I am not here to rain on your parade, but I would do all the checks to determine if it is indeed the head.



Run it without the thermostat for a good day and see if you still get overflow. If so, then a leakdown test of the cooling system would be next, if it leaks down then off comes the head if no leaks are detected in the heater or pump/hoses.



I truely hope for the best.



J-eh

 

[Dfeland]

I think that I would put a new radiator cap on first just to make sure that its not blowing off pre-maturely. Good Luck.

 

[wxman]

Thanks for the responses. The local Dodge service department thinks it is a blown head gasket. I have an appointment next week. I just hope it's not a cracked head!