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Jeep Grand Cherokee Engine Swap Problems

A while back my Jeep Grand Cherokee began making a distinct tapping noise. After describing the problem here and receiving plenty of responses, the conclusion was a damaged lifter. After thinking things over, my dad and I decided that doing an engine swap would be the way to go, seeing as the old engine already had 176K miles on it. We ended up buying an engine from a 96’ Jeep Grand Cherokee, with 130K miles on it. Long story short, we finished swapping the motors today, went to fire it up…and of course it didn’t work. We tried it around 10-15 times, with nothing. Here are the details of the swap:

What parts we put put on from the old engine:
-We put the flywheel from the original engine onto the new engine
-Intake and exhaust manifold
-Accessories (power steering pump, water pump, AC compressor, and fan/fan clutch)
-Ignition coil
-Distributor (distributor, distributor cap, and wires)
-Wiring harness / ECU

What we observed:
The engine would sound like a normal cranking engine for most of the attempts, but it just wouldn’t want to start. A few times it sounded like it was about to start but quickly died. I noticed some smoke was coming back out from the intake (exiting near the air filter).

We really put a lot of time and effort into swapping this motor so I’m hoping we didn’t make some dumb mistake (we did check all the wiring and other connections). My first guess is that maybe we shouldn’t have removed the distributor from the old engine and put it in the new on, because although they were nearly identical they did have different part numbers. If this is the case, is it as simple as returning the old one or is there something else wrong.

Nikola Hrgic

Have you checked for spark and fuel delivery?

Did you time the distributor when you dropped it in? They just cannot be dropped in, they have to be timed. The engine rotated to TDC, and the rotor pointed to #1 cylinder is a first start. The distributor then must be adjusted to find a narrow band of timing between 10 deg BTDC to 25 deg ATDC to get the engine to start. Once running, the distributor must be further adjusted to proper ignition timing.

I think BustedKnuckles is on the right track here. You must install the distributor properly and then adjust it. Question: Are the year model for the replacement engine and the year model of the Cherokee a match? If not you may also have other problems because different model year engine and vehicles sometimes have a problem interchanging.

I also think the distributor change has disrupted the timing. You need to find Top dead center on the ignition stroke (which means you have to confirm all the exhaust and intake valves are closed). If you can’t figure that out, then tow it to a shop for putting the distrubutor in properly.

Well it appears that we were novices when it comes to engine timing. We simply put the new distributor in without doing any of the steps you described. Could you give me some tips or procedure method as to how we should make sure cylinder 1 is at TDC. By the way, we did try putting the rotor to the #1 cylinder, but the distributor won’t go all the way in. If i remember correctly, the flat head screwdriver-like end of the distributor is used to drive the oil pump, so we weren’t able to get it to fit into the receiving end.

Pull the #1 spark plug. Roll the motor till it starts to push air out. Then roll it till the timing marks line up on crank pulley and timing tab. Then point the rotor at the #1 terminal on the cap. Using a long screwdriver turn the oil pump the line up. Now put the distributor in,you may have to roll the motor a bit to get to drop in.
This may not be the exact way to do it on your motor. You should get a manual for your Jeep.

@oldbodyman: thanks a lot for the advice. I’m assuming that timing will still need to be adjusted afterwards with a light gun, or am I wrong?

May be with a light or a scan tool. You will have to check the manual.

Okay, the engine is out of a '96, what year is YOUR jeep?

@Caddyman: my jeep is a 98’ Jeep Grand Cherokee Laredo.

I just got the service manual for the car and all I can say is sorry for being such a novice. The manual describes, step-by-step how to put the new distributor in and everything. I’ll let you know if that was in fact the problem. Thanks for all the help guys.

We followed the service manual instructions on installing the distributor and it started up the first attempt. Once again, thanks for the advice.

Good for you!!