I want to swap my 1989 Jeep Comanche 4.0 for a 1999 Jeep Grand Cherokee 4.0! Are the motor mounts and the block the same

[Gray]

B

[ghetdjc320]

The 99 grand Cherokee is a WJ and I don’t believe it swap easily. Aside from physically mounting it you will have to address electronics. 99+ are coil pack engines iirc. Renix intake manifold won’t fit either. It is also an obd2 engine. Nothing’s impossible but it’s far from a bolt in swap. 

[cruiser54]

CRUISER'S MOSTLY RENIX TIPS

HO INTO RENIX SWAP

OCTOBER 31, 2015 SALAD 56 COMMENTS

 

This swap is easier than some will lead you to believe. And generally Pooh-poohed by those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.

• XJ Cherokee and ZJ Grand Cherokee 4.0L engine blocks interchange.
• 2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.
• YJ and 1997-1999 4.0L TJ blocks will interchange in XJ/ZJ
• XJ/ZJ blocks, and the 2000+ TJ/WJ blocks do not interchange without significant modifications.

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.

Now that we know which engines we can use, let’s get down to business.

The HO and Renix have some differences but none that can’t be overcome very easily.

One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from an HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head at the rear for the sender.

You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use a new Renix gasket. Exhaust ports are identical.

An alternative on exhaust manifolds:

As far as exhaust, you can use the Renix exhaust manifold and be fine.
If you want to use the HO exhaust manifold, you must go with an HO headpipe and screw your O2 sensor into that headpipe. Standard Renix harness is plenty long to do so.
A bung can be welded into the HO manifold to accept the EGR tube.

You will need to use your Renix distributor as it is different than the HO design. See Tips #12 – Setting Your 4.0 to #1 TDC and #13 – Distributor Indexing to be sure you get the distributor installed correctly.

The flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.

The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.

As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.

 

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)

[ghetdjc320]

I swapped in a 96 XJ block which was the first year it was updated for “noise vibration and harshness”. It has more internal webbing along with a girdle for the crank mains. It was an obd2 engine but I didn’t reuse any of the electronics. I just wanted the block. Easy swap. My post was not intended to discourage you from swapping, you just need to know the WJ block doesn’t fit. 

[ghetdjc320]

7 hours ago, cruiser54 said:

. Since the intake ports of the HO are slightly different, you use a new Renix gasket. 

Somone had a renix engine in my 91 MJ eliminator when I bought it. It was just the block and head that were renix but it was running on the HO components. I know the renix intake manifold technically fits the HO head but it does not match up like it should and just installing the renix gasket doesn’t make up for the difference. 
 

 

[cruiser54]

11 minutes ago, ghetdjc320 said:

Somone had a renix engine in my 91 MJ eliminator when I bought it. It was just the block and head that were renix but it was running on the HO components. I know the renix intake manifold technically fits the HO head but it does not match up like it should and just installing the renix gasket doesn’t make up for the difference. 
 

 

 

It works fine. The HO gasket ain't that close to port size either. 

[ghetdjc320]

38 minutes ago, cruiser54 said:

 

It works fine. The HO gasket ain't that close to port size either. 

True, but the intake at least lines up. 

[75sv1]

Not an easy swap. And yes, I've tried and am trying too. The first issue is the motor mounts.  I have gotten this far. The  WJ vs the XJ/ZJ block, the offset of the diver's side vs the passenger side is flipped on one of the bosses. I created a spacer on one side and then had a mount cut and welded on the other(drivers side).  

     The next is the accessory driver. This one is holding me up. The bosses are there to be drilled and tapped. Still, not sure I want to go there. Also, the water pump, the bolt hole pattern is a bit different, and I think the pump rotates in the opposite direction. I am planning to keep the WJ accessory drive and use an electric fan. My problem is I swapped on a '95 head. There is a pulley that attaches to the head. I'll have to weld up a bracket to place the pulley. Overall I do not think it is worth all the hassles.