Thanks

 

Is taking off the fuel rail as simple as unbolting the few screws holding it down and pulling it out?

Id like to clean up the heat shield and paint it and would also like to change injector o rings while im at it.

 

yes

 

Dukie has an insanely good write up with pictures i the sticky section. If you haven't done so already, changes your injectors while you're there so as to kill 2 birds 1 stone

 

Should I be worried for the injectors to not reseal if I dont replace them and just pull the rail?

 

x352468

Be firm and patient in removing the rail.

At the bare minimum replace the O-rings. Since you have a Renix I'd be worried about the injector bodies cracking and leaking just by looking at them.

 

When removing the fuel Raul on a Renix, be very, VERY careful not to break the MAP line to the throttle body.

 

What is the newest motor I can put in my 91 XJ?

 

XJ Cherokee and ZJ Grand Cherokee 4.0L engine blocks interchange.

2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.

XJ/ZJ blocks and 2000+ TJ/WJ blocks do not interchange without significant modifications. (1991 to 1995 YJ and 1997-1999 4.0L TJ Wrangler blocks will interchange in XJ/ZJ and visa-versa).

TJ/WJ 4.0L Engine blocks underwent clean sheet design changes effective in the 1999 WJ Grand and 2000 TJ Wrangler. These blocks are not interchangeable with XJ/ZJ engine blocks. The reason is motor mount bolt holes and belt driven accessory mounting bolt holes are in different locations, or not present at all, TJ/WJ vs. XJ/ZJ.


XJ: "Regular" (not Grand) Cherokees 84-01
ZJ: Grand Cherokee 93-98 (Gen1)
WJ: Grand Cherokee 99-04 (Gen2)
YJ: Wrangler 87-95 (Gen1)
TJ: Wrangler 97-06 (Gen2)

 

Up to 2001 XJ will work. Anything newer than 1996 will need you to figure out how to deal with the temperature gauge.

 

Can I run my gears without a pinion shim?
Reason I ask is cause when I have my backlash set right my drive pattern is way off to the toe end of the gears and my coast is way to the heel.
From what I've read that means I need to decrease pinion shim but I only have one shim in there now and it's the smallest I have

 

Are the races fully seated?

 

Well, I think I ran into my first major problem, and I don't think I am going to like this one. My wife and I drove the XJ up North about 100 miles to her parents for the weekend. When we got out after the ride up there, I noticed my coolant was boiling. The engine temp was fine the whole way up. (When we got off the freeway, I did notice that it went to the next notch after 210 but the fan was on and it went back down quickly.)
Well, after the drive home, when I got off the freeway, it sat idle at the light and the temp rose again, but this time it suddenly jumped all the way up and the "check gauges" light came on. I pulled it into a parking lot and popped the hood. The coolant was boiling again and the engine bay seemed extremely hot. We were only a few miles from home so I let it sit for about 10 mins and then started it up, it started poorly and didn't idle very well for a minute, but then it evened out. On the way home it drove fine and the temp was just a tick over 210.
The oil pressure sat at around 50 most of the way home as well.

My first guess is that it needs a new head gasket. I am really hoping the head isn't cracked.

What do you guys think? Thanks.

 

Yep, I even crushed the crush sleeve already and tourqed my pinion nut

 

try replacing the thermostat first sounds like yours might be getting stuck "closed". xjs typically run hot mine normally runs around 210 or a lil over in traffic or on the highway. As long as it doesn't boil over you should be fine. did it ever go into the red?