1991 Manual B2200 Overheating

My boyfriend drives a 91 b2200 and it seemed to start overheating badly recently. Its overheated in the summer before, but never this bad. His water pump is good, he replaced the thermostat and fan clutch already, he also flushed the radiator with distilled water and replaced the coolant. and even though its gottenbetter, it is STILL overheating, just not as quickly. It takes about 10 minutes. The truck has no other issues other than the rear main seal needing to be replaced, and a rough/low idle sometimes. We were thinking maybe its a blown head gasket or maybe the new fan clutch is bad? Or maybe the thermostat was faulty?

We just have no idea what else it could be.

Please help! We are at our wits end.
This truck is my boyfriends dream, we don't have alot of money, and its really stressing us out. Any and all suggestions are appreciated!!!

I also had overheating of my 1988 B2200, but mine wasn't the head gasket, it was just the radiator getting old and not shedding heat well. I installed a new 2-row radiator into mine, and now I'm below half-way up the gauge, and that's with AC on and Interstate uphill, Arizona summer.

A cylinder leakage test can pinpoint if the head gasket is bad/leakage through head gasket. Is the truck smoking white smoke out the tail pipe? Any oil in the coolant, or any coolant in the oil (appearance)?

Welcome to the forum alexusl0l.......

Keep a close eye on the oil color......if the oil is new, it should stay golden colored for a few weeks at the very least......longer if you don't drive it much. If the oil is old, it will be a black or brown color. If there is coolant in the oil, it will be a milk chocolate color, and there will be a whitish colored film inside the valve cover and inside of the oil fill cap.

If the head gasket is blown, you could also get some bubbling out of the dip tube inside of the radiator overflow bottle.

If none of this is happening, then get a new radiator......as Cusser has stated. As they get older, the sediment begins to clog the lower portion of the radiator cores.......the only way to fix it is to have the radiator professionally cleaned.

In my area, most of the radiator shops have gone by the wayside, maybe a few in central downtown Phoenix, as the cost of brand-new radiators has dropped.

The radiator gets clogged by solder bloom. It's corrosion that grown on solder. Plus corrosion from aluminum parts in the system and rust from steel/iron parts in the system. This happens inside the tubes with the white calcium like substance that slows the water and keeps the tubes and fins from transferring heat. In northern climates where salt is used on the roads the mixture will corrode the fins. They are very thin and actually have louvers on them. This corrosion will degrade the heat transfer.

The repair at a radiator shop involves them running it through a vat of heated caustic soda in water to loosen the corrosion then flushing it then taking the top tank off and running a stainless steel flat rod down each tube then putting the tank back on, re soldering the necks, pressure testing then flushing again, then paint.

It will be like new. I used to work at a radiator shop for 14 years. I did thousands and it's cheaper than replacing the radiator. But not by much.

There is one advantage to a radiator shop and that is you can have a thicker core installed in the tanks. Like a 2 row or three row HE (high efficiency) core installed. These have a higher tube and fin count. The tubes are smaller and closer together and more fins also. These will cool much better.

Other than that the price of new ones dropping like Cusser says is the best option.

Always check the thermostat. It can stick partially open even if it's new.

Good post. And do not run without a thermostat, it's there to get you to operating temperature (less wear) quicker. And that will not cure a hot system anyway if the thermostat is "good", should only - and if - be used as a diagnosis tool. And with Mazda and Stant thermostats not being expensive, not really worth the effort either.