Questions about my 2000 XJ

About 3 weeks ago I purchased my first new to me XJ. From a reputable used car dealer. The day after I took delivery I got the CEL. It came on after engine missing on a hot restart, #3 cly. misfire. Research led me to the heat soak problem. Installed insulators and still had the problem.
Took it back to the dealer for them to check it out, its still under their warranty.
They called me yesterday and said that they found the problem. Seems as though the head is cracked! So as a result they are going to install a new (remanufactured) motor, and it will have a 100k warranty.
Can anyone tell me their thoughts on whether this will fix the heat soak problem? :confused1
All the XJ's that I see driving around this area its hard for me to believe that they all have a CEL on.
I know the older ones don't seem to have this problem, but still are alot of 00 and 01s out there.
Thanks for your comments.

You got the 0331 head which has a reputation for cracking. You really lucked out as you now have a great year XJ without the cloud of a cracked 0331 head. Now just swap in a HP front axle and you good to go! BTW, your problem was not a heat soak problem, it was a cracked head.

Some say that the 0331 head will be OK if the milage is over 100K. What is on yours?

the 00 and 01 XJs had issues with the head used on the 4.0. you can try searching around about the 0331 head to get more details. it was an issue with the way it was cast. many many XJs with that head end up with it cracked. if they replace it with another engine with the same 0331 head, it may happen again. good fix is to use an earlier head, i forget the casting number. the other head is from the engine type that still had a distributor.

not sure if it'll solve the heat soak issue, i doubt it. maybe some else can chime in there.

Miles is at 96k.
Oh crap, whats up with the front axle?

2000-xj said:

Miles is at 96k.
Oh crap, whats up with the front axle?

Click to expand...

NOTHING!

2000-xj said:

Miles is at 96k.
Oh crap, whats up with the front axle?

Click to expand...

2000+ had low-pinion (LP) Dana 30 front axles. some people take this as a clearance issue and opt for the high-pinion (HP) Dana 30 from 99 and older models. its really not a big deal, dont worry about it. and welcome to the forum!

Thanks for the welcome and explanation on the axle.
This is a great place to learn.:rof:

snail said:

2000+ had low-pinion (LP) Dana 30 front axles. some people take this as a clearance issue and opt for the high-pinion (HP) Dana 30 from 99 and older models. its really not a big deal, dont worry about it. and welcome to the forum!

Click to expand...

Heat soak is a 99-01 issue in the XJ; TSB 1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK Date: 09/05/03 (supersedes 1802702 dated 09/06/02) Model Year(s): 1999-2004.

Essentially, the TSB fix is to wrap an insulator around the number 3 injector. Good luck with that.

To confirm if your problem is heat soak, drive the vehicle so it is good and hot, park and shut off the engine, then open the hood and let it sit for 30 minutes. If, on restart, the problem is gone or greatly diminished, then you have heat soak.

If you have heat soak install a timer for the auxiliary fan so it will run about 5 minutes after the engine is shut off. Muddeprived has a couple threads on his epic journey with heat soak. Search.

joe_peters said:

Heat soak is a 99-01 issue in the XJ; TSB 1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK Date: 09/05/03 (supersedes 1802702 dated 09/06/02) Model Year(s): 1999-2004.

Essentially, the TSB fix is to wrap an insulator around the number 3 injector. Good luck with that.

To confirm if your problem is heat soak, drive the vehicle so it is good and hot, park and shut off the engine, then open the hood and let it sit for 30 minutes. If, on restart, the problem is gone or greatly diminished, then you have heat soak.

If you have heat soak install a timer for the auxiliary fan so it will run about 5 minutes after the engine is shut off. Muddeprived has a couple threads on his epic journey with heat soak. Search.

Click to expand...

Talking about the heat soak, I did the fan timer thing & all is good.
But the actual cause of the heat soak, Is it the fuel boiling in the rail or, As the owner of a very good auto repair shop told me, Is it the Coil Pack getting hot!
He claims to have replaced the coil pack on a few jeeps that had the symtons & it cured the problem!

garr said:

Talking about the heat soak, I did the fan timer thing & all is good.
But the actual cause of the heat soak, Is it the fuel boiling in the rail or, As the owner of a very good auto repair shop told me, Is it the Coil Pack getting hot!
He claims to have replaced the coil pack on a few jeeps that had the symtons & it cured the problem!

Click to expand...

Fuel boiling in the injector more than the rail.

There have been posts on here of owner's replacing coil packs that had heat/stress cracks and were shorting to ground when hot. If you think that is your problem put it in fault mode then start spraying water from a bottle around the coil packs--should give you some interesting results if that is the source of the miss fire.

The timer's run about $30 with shipping, ELK-960 is a good one. How much is a coil pack going for these days?