lxrubin

1997 XJ sport 4.0 4 dr. Need help to get car running and out of this dessert. Need advice on what might be the problem.

On the way into Moab, the car overheated, I think due to running the AC and electrical fan starting to go. I let it cool, checked oil+coolant for contamination, added water and I was off again. I did a Moab excursion without a problem, and on the way out of town, it started acting up. Would hesitate off idle, and start racketing. The racketing I think is lifters as it's on/off depending on load and doesn't get louder, just faster with rpm.
I started to hear a really bad noise I thought was one of the pulleys but after completely removing the serpentine belt, it ended up being the electric fan. I turned around and made it to a shop and they changed the fuel pump filter (part of pump asm). Apparently, they go when hot. The fuel pressure was checked before and after and went from 25psi to 52psi. I stayed in a motel and have since changed the plugs, wires, cap, rotor, coil, and crank sensor. The plugs were really bad, wires suspect. I checked the compression cold and all were 100-125psi. When warm #6 jumped from 115 to 135psi. It was too hot to verify the rest tho. I changed the oil & filter and there wasn't any coolant or other contaminants obvious. The oil pressure is low when the engine is struggling but appears to be normal once revving. Air filter appears to be clean, but ill change that out next just to be sure.

It hesitates a lot off idle, and I need to feather the clutch hard. Once moving it appears to have reasonable (maybe even normal) power.

I'm contemplating waiting until it's cooler and start driving it out of town since most of the issues are heat related.

Morat

So, did you fit a new electric fan? - and how is your mech fan clutch?

BlueRidgeMark

Ugh. That compression is really low. You may have toasted that engine.

But there might be hope. Was that crank sensor a Mopar or aftermarket? They are really picky, and aftermarket CPS have been known to be bad out of the box. All the way from completely useless to just running really badly.

Another suspect is the cam sensor in the distributor.

lxrubin

Turns out it was the radiator was cracked. The overflow was full so I didn't think to check the level in the rad directly. Fixed the rad and now shes running smooth. In Cali now near the Rubicon trail.

investinwaffles

Hopefully she didn't get too hot on you.
Just keep an eye on it and change out that e-fan and probably the mech fan clutch as well. Make sure the AC Condenser is clean and no bugs, mud, or road film on it so you get max air flow to the radiator.