The first Universal Truth is that the last guy to work on it (or girl, I don’t judge) was a complete hack.
The second is that there really is no such thing, largely because of the first Truth.
There are others, but they generally lead back to the first couple.
I set out to change the radiator in the new-to-me MJ, in part because it was crusty as all hell, and in part because it apparently had a very sudden and severe overheating problem.
I’m willing to excuse the last guy did this one, but the shiney part is from the bolt spinning uselessly. The nut on the back is secured in a rubber bushing, but the two are now two distinct pieces. Eventually I gave up and just pulled the two Torx screws securing the whole bracket.
I also had a water pump for it because I figured why not. I was actually surprised at how clean it looked. It can’t be original. But I put the new one on anyway. I suspect it’s been weeping but it’s hard to say because of all the goo coming from the thermostat housing and valve cover gasket.
It wasn’t seated properly in the housing, preventing the sealing surfaces from touching. Instead of sitting it in there properly, they just used a ton of RTV to “seal” it, with it looks like the old torn gasket still in there. And it kinda worked, I guess.
But while I was doing that I noticed that the air box clips were all undone. Instantly suspicious, I popped it open, expecting so see a squirrel nest, or something else under the filter... Except in reality all that was in there was an oily schmoo along the bottom of the box.
The guy said the oil had been changed shortly before the overheating incident, and it looked pretty good, so I was just going to let it get to the next even change interval, but seeing no air filter meant it got changed today too. And while I was doing that, I had another WTF moment.
For something that lives in oil vapours and should be getting wiped clean fairly regularly, why is there RUST on my dipstick? How? Before you ask, there was no sign of coolant in the oil, which is a good thing.
However I’m less sure about the coolant itself. The cause of the severe overheating is because there was only about a quart of coolant in the system. And it was murkier than all hell.
That sample is the last of the third gallon of clean water I dumped through the block. Hurk. It had that odd smell of artificial smoke flavouring to it. It didn’t seem like there was oil in it, but when it’s that bad, it’s pretty hard to say.
The “suddenness” of the overheating pretty clearly is because the truck came with an idiot light instrument cluster. The PO changed it out for the full cluster. This is all well and good, but they didn’t change out the sending units. As such the oil gauge simply pegs itself because the signal it’s getting instead of a pressure is either “yes” or “no”. Ditto for the temp gauge. It reads zero if it’s not overheating, then instantly pegs itself the second it overheats, except without a polite accompanying light. Then eventually the engine just gives up in protest because no one noticed the heat. And with near zero coolant, there’s almost none of the typical overheating symptoms.
This is how I’m leaving it for the night. New water pump, thermostat, gaskets, serpentine belt. The radiator’s still in its box. I’ve got a full set of tune-up/ignition components that’ll be at Napa for me tomorrow. Hopefully that takes care of the hard starting. I really can’t trust any of the fluid or wear items on it now.
I still have to do something about the questionable brakes and the whole whack of vacuum leaks I accidentally discovered today. Like this one:
It’s a PVC elbow failing to seal off a tube that’s about 1/2 the size of the rubber elbow. This leak alone was about a 300rpm drop in idle speed. Crazy.
As to the second Universal Truth... I’m about $500 deep in parts and already, and this is just to make it run properly.