eddielane71488

I have recently procured a 99 WJ that has been overheated to the point of failure. It is 4.0 and one of the later ones at that (coil-pack ignition)

I also have managed to get an engine form a friend who labeled it as a 98 Cherokee 4.0 liter... It has a distributer, bit I don't have a sub-model of the jeep it came out of.

My question is, can I put that engine in my jeep, and how can I ensure that overheating will not be a problem?

P.S. Have already done the radiator, t-stat, upper and lower hoses. when the overheating started.

As explanation, I was stuck in slow moving traffic and could not get over to stop before it was too late...

dave1123

If the motor mounts are the same, you can put it in. It may be a problem getting it to run, however. You'd have to use ALL the electronics and sensors from the WJ, as well as the ignition system. I'd be willing to bet the reason for the WJ's overheat was a shattered water pump impeller. It was probably plastic.

eddielane71488

the only thing I was worried about the ignition system. taking a distributer block and putting the coil pack system on it...

I keep seeing something about the head being different, where the coilpack bracket mounts. Any idea if this is true?

eddielane71488

Is there a better water pump for these?

dave1123

Yes, there is. When I replaced the pump in my 97 ZJ 4.0, I went to NAPA and looked at what they had. The OEM replacement had a plastic impeller, but the Premium pump had a metal impeller. Guess which one I bought.

There was a little history here. The one I replaced had a bad bearing where you could move the fan blades about 1/2 inch up and down, but the seal wasn't leaking. When I removed it, there was a bright groove in the first cylinder barrel where the impeller had been hitting it, causing the noise I was hearing. When I started to install the new one, I tried to spin the impeller before tightening the bolts. It wouldn't spin. I took it back to NAPA and we inspected it, comparing it with 2 more off the shelf. It seems the impeller wasn't installed on the shaft far enough and the difference was only 1/16".

SO. If the pump impeller spins that close to the cylinder, which would you want in your engine?

Getting back to your engine. The cylinder heads may be different, however I'm told the older one is better than the newer one anyhow. The newer intake manifold flows more air, so I'd use that. Another difference is the oil filter location. My 97 had the filter mounted on an adapter just above the oil pan with the pressure sensor right next to it. My WJ has it screwed directly into the block and the pressure sensor moved to the side of the block near the rear corner. Use the WJ's sensor.

eddielane71488

Ok, so the motor mounts are not the same, the oil filter isn't the same, and the head isn't the same... I guess I'm going to have to find another option...

Thank you for your help!

wheelerboy12

Whoa whoa, no, not time to look for a different option, time to get to work.

You Can put that motor in your WJ, you need to use the WJ sensors, ignition, the head IS different, BUT the differences are a plus, the older model head outperforms, but the intake from your WJ is better so use it, There should be no difference in motor mounts, its a 4.0 use the mounts from your WJ they should bolt to the block just fine.

Good luck.

pwb

I also had that groove, but are you sure that isnt made in the factory? There should have been a lot of metal inside, but in mine it was fine.

dave1123

No, all you could find is some iron filings if the impeller was metal. That groove was NOT there from production. If the impeller was plastic, you'd find some plastic shards in the bottom of the block. Generally, they don't impede coolant flow enough to matter. If the groove is rusty, it's from a previous pump.

On the motor mounts, if the location and bolt pattern is the same, you could use ANY mount. I've been told that some use a different location and those won't fit. Wheelerboy seems to have done this before. I think the dipstick tube may be in the way of the coil packs, but I'm sure you can deal with that. Use the tube from your original motor. You might have to modify the support bracket if there isn't a bolt to mount it to.

eddielane71488

The WJ motor mounts will not bolt to to the block. The bolt patern and even the lateral location of the mounts is not the same...

dave1123

Okay, I know when I'm out of my league. When I originally told you that if the mounts were the same, meaning in the same location, you could use the engine. What the engineering decisions were to change the block, I haven't a clue. Maybe if you PM'd one of the older guys here, you could get the years of the engines that WOULD fit.

eddielane71488

in 1999 they redesigned the engine block. The engines that came before 1999 in the Cherokee class will not bolt up to the mounts post 1999...

dave1123

Okay, there you go. After doing some research myself, I came up with the same answers. Any 4.0 1999 and newer will fit.

It seems the problems with the later "Power Tech" heads cracking is caused by the ports being larger thus thinning the walls in the passages. This is just supposition on some people's part and should not be taken as fact.