Hi all, I recently picked up an 89 renix 4.0 4x4 MJ and it's running pretty consistently at about 250. It was originally closed cooling, but I accidentally popped the pressure bottle and decided to go ahead and just swap over to the open system with a new radiator and overflow bottle. I removed the heater control valve as well. So, fortunately I don't have to futz around with the closed system, but I'm still running just as hot. Here's everything I've tried so far:
I flushed the originally coolant, which was not particularly cruddy looking, but figured that was a good starting point. I think I did a pretty good job cleaning out the engine and the heater core. I've since ran a few changes of cleaner fluid and distilled water through it.
I replaced what looked like the original thermostat with a new stat. I boiled both of them and they appeared to open at 195 as intended.
I have checked my gauge and read the sensor with an IR thermometer and I believe them to be working and reading correctly.
I have checked my fan clutch and it seems to be in great condition as well as the blades and my ducts.
My efan was not originally running, but I have bypassed the AC low pressure switch to have it running all the time (turns on if I jump the temp sensor from the rad as well but i haven't ordered a new sensor yet), but that has not helped temps.
I did a dry compression test and got a 130 across all 6 cylinders (didn't have any oil at the time, but numbers seemed good so I haven't done a wet test yet)
I am reading about 190F at the upper rad hose and about 170F at the lower hose. Someone told me on a facebook group that I should be getting about 20F difference which seems right, not sure if those temps themselves are high or low though.
My tailpipe is shot and leaking like crazy, and there is a small hole where the muffler dumps into the tailpipe, but I assume this is irrelevant. As best I can tell there are no leaks elsewhere in the pipes or around the cat.
I just failed emissions with high CO. Not sure if that's correlated.
As far as I am aware there is no smell of exhaust in the bay, nor any strange noises.
I am suspecting my water pump is pretty corroded or my head gasket leaking exhaust into the coolant. I also saw a video talking about the harmonic balancer wearing out that can cause overheating as well, but by eye it looks fine, not sure if there's any other clues without pulling it.
Keep in mind I'm just a dingus with some wrenches, if I missed any critical info please let me know, or if there are any tests I should be able to do. I'll keep the original post up to date with anything I might have missed as it comes to mind. Any advice appreciated!
