My new to me 82 CJ with a 258 is overheating. We recently replaced the original radiator because a previous owner must have patched a crack on the upper hose neck with JB Weld and it wasn't holding so well. After replacing the radiator, a short drive of only 2-3 kilometers and the coolant would start boiling over into the overflow bottle and we'd leave most of the coolant on the street, because it would overflow from the bottle.
We replaced the radiator cap with a new one, swapped out the thermostat and the water pump, all without any change in the symptoms.
An interesting thing though, with the radiator cap off, while the engine is running, if you pump the throttle a little, instead of the coolant level dropping, it gushes out after a moment. Normally, I'm accustomed to seeing the level drop a little.
So, we're thinking that the pump may be turning the wrong way. We've ordered a new one that turns in the opposite direction, to see if that helps but the impeller on the new pump turns in the same direction as the one it replaced. We're assuming that maybe it was the wrong pump to begin with, that maybe a previous owner had installed the wrong pump. The fan and pump turn clockwise but it appears by looking at the impeller that this is the wrong direction.
If a different water pump doesn't solve the problem, then we'll get a combustion gas tester, to see if there are combustion gases in the radiator, which may indicate a blown head gasket. We've not seen any white smoke coming out of the tail pipe, nor are we seeing any changes to the new coolant. Mind you, the coolant hasn't been staying in too long and we keep having to replace what ends up on the street. Also, when we filled the coolant system with a vacuum system, we didn't detect any symptoms that might have lead us to believe that there was a problem with head gasket or the block. A pressure tester at the radiator cap shows that the pressure gets up to 20psi within a few minutes and this pressure just pushes all of the coolant out of the system and into the overflow bottle, which then overflows onto the street.
So, suggestions, words of wisdom?