Looking for an Engine

I'm looking for a replacement engine for my 1991 Laredo. I am seeing some engines posts that say "4.0L, VIN S, 8th digit". I get the 4.0L, but what's the rest mean and is it relevant to my search?

You had the 91 wouldn't start at first?

Um you can use just about any 91-99 xj 4.0 most others grand Cherokee, wranglers up 98. It's a big pool to choose from, the vin is just what identified the 4.0 that year, some manufactures motors it identifies the plant any type of engine - carbureted- tbi- injected. For the 90s 4.0 it's a just about all the same motor except for a few small change.

I have a 95 motor I picked up to rebuild for a 91-92 xj. Stuff like valve cover and sensors change but just treat it as a bare long block and swap all your accessories and other items over.
Other big change is how the oil filter mounts between the years, really doesn't matter. Usually when I swap a newer motor I just make sure to buy for that year motor or swap the housing if possible .

If you find a candidate I'm sure some one here can tell you that year and keeps quirks for transplant


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Would a 97 Grand Cherokee 4.0 work?

I think grand Cherokee swap until 98 ZJ, I believe 97 is good with a few things like sensors and possibly the head on the 97 not having the hole for the temp sender at the back of it. But all this can be worked around, the bock should be good to go, after 98 the GC WJ & TJ block change so Are not good for the xj


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You could swap heads around on the 4.0 cant you? or are the passages slightly different?

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 the 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)

I'd buy a running 2WD xj and steal it's sweet six cylinder goodness. On the plus side, most of them had 8.25s.

Gave $300 for the last one and it proved a good donor for tons of stuff. Sell the 2WD AW4 for half of the initial investment. Use the rest of it to store parts for future projects.

sinat01 said:

You could swap heads around on the 4.0 cant you? or are the passages slightly different?

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Yeah its all pretty standard with some minor qualifications for the years. Some blocks and heads have pins to line them up some don't, some heads are slightly different for sensors but the oil passages should all line up with the various years 4.0.

Cruiser54 just laid down the facts on the 4.0 interchange in the last post, follow what he says, if he tells you different on the heads follow his advice, he's the one to listen to.


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Overland said:

I'd buy a running 2WD xj and steal it's sweet six cylinder goodness. On the plus side, most of them had 8.25s.

Gave $300 for the last one and it proved a good donor for tons of stuff. Sell the 2WD AW4 for half of the initial investment. Use the rest of it to store parts for future projects.

Click to expand...

True, I've seen some cheap 2wd xj for sale essentially for parts.


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I've got a 2dr 2wd 4.0L 1993 in my yard if you want it.

Engine and tranny are good, I just needed the quarter glass for my rig. The truck is going to the scrap yard ASAP.