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Questions about swapping different year/model 4.0s

Yellowjeep1

NAXJA Forum User
Location
Tucson Az
I have a 01 witha cracked head and wiped cam bearings, I want to swap it for a pre 0331 head engine. I have read that the 91-01 cherokee and 93-97 grand cherokee blocks are the same, Is this true? What year Wrangler blocks will work? Other than the coil pack mounting you have to fab to use the 01's distributorless ign, is ther any reason an older motor wouldn't work?
 
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 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 have a 01 witha cracked head and wiped cam bearings, I want to swap it for a pre 0331 head engine. I have read that the 91-01 cherokee and 93-97 grand cherokee blocks are the same, Is this true? What year Wrangler blocks will work? Other than the coil pack mounting you have to fab to use the 01's distributorless ign, is ther any reason an older motor wouldn't work?

I have yet to confirm all of this independently - it's all reports from the field - so take it with a grain of salt...

- There are mounting differences (block-to-chassis) between the YJ/TJ version and the XJ/MJ/ZJ/WJ version. This can't generally be swapped.
- Within models, mounting did not seem to change through the years, so they may be swapped freely.
- ANY 6-242 head can be mounted to ANY 6-242 block, regardless of model or model year.
- The 0331 head up through mid-2001 was fit only for scrap - look for a replacement with the TUPY foundry mark under the oil fill cap, this is the revised head that should last. Available late 2001-2006, this can be retrofitted in place of an early 0331 head without difficulty.
- If you "roll back" to an earlier head (0630, 7120,) know that you may need to fabricate an adapter plate to use the 0331 exhaust header with the earlier head - with each revision, the size of the exhaust ports was reduced, ostensibly to improve catalyst light-off time. The "adapter plate" would actually be a block-off, meant to cover the bits of the port that aren't covered by the primary tube entry. This may easily be fabricated using decent mild steel (I'd go at least 0.090" thick,) use the correct gasket for the head on the head side, the correct gasket for the exhaust on the exhaust side, and make the exhaust holes in the plate match the holes in the EXHAUST MANIFOLD (not the cylinder head!)
- Further, if the above is done, brackets are usually readily fabricated from sheetmetal to support the coil rail, attaching them to the screws for the valve cover.
- While the 2686 head (1987-1990) WILL mate to the block, its use is NOT recommended, due to the shift in location of intake ports for the 1991-up model years. Easier to just get a later head.

Anything further you'd like me to dig around for?
 
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 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)




Refinement to information I've gathered, I see! I'm trying to get a source with whoever runs Jeep now, I'd like to get a set of prints for the production life on the 6-242 engine, and confirm this mess once & for all...
 
Thanks for your insight.I should be able to install a header to get around the exhaust problem. I 'm trying to keep this as simple.as possible, as I am probably be buying an out of state engine and shipping it in. Since I won get to inspect it in person, to check casting numbers etc. It seems the best bet would be to stick with a 96-9801 xj engine.
 
Thanks for your insight.I should be able to install a header to get around the exhaust problem. I 'm trying to keep this as simple.as possible, as I am probably be buying an out of state engine and shipping it in. Since I won get to inspect it in person, to check casting numbers etc. It seems the best bet would be to stick with a 96-9801 xj engine.
91-95 blocks are basically the same as well. I have a 94 block in my 98 for instance. I had to cut off the timing light boss thinger on the aluminum timing cover to clear the later belt path, it took 5 minutes with a dremel.

Exhaust is going to be fun, since you have an 01 with precats, you have 4 o2 sensors and 2 precats. I want nothing to do with that mess and trying to make it fit older engines so I just don't buy 01s or cali emissions 00s...

The only difference is putting a later motor into an earlier jeep, you have to tap a hole for the temp gauge sender in the thermostat housing because they eliminated the hole for it in the head halfway through 97.

Also, you may need to put an adapter on or mess with your exhaust system to fit 00/01 exhaust onto a non 0331 head. But yes it can and has been done.

5-90, I put a 94 XJ 4.0 into a friend's 87 YJ that came with a 4.2. It fit fine, though we did swap all the XJ accessories and such as well, all the bosses appeared the same when comparing them pre-swap. YJ/TJ motors are stupid expensive around here "because it's a wrangler motor" so I avoid that anyways, even though afaik they are the same, junkyards and private sellers alike think that anything that came off a wrangler is instantly worth big money. By big I mean that they want 800 bucks for a YJ 2.5L and 4-500 for axles while any XJ engine is 100-150 and axles are 100-130. It's retarded.
 
What if I went with a 98short block or rebuild this one, although I've heard they had block problems in00 and 01in as well, and found a newer head? Would ththe newer head have the same exhaust and coil mountings as the 01best 0331? What are the casting numbers of the newer heads TUPY foundry etc. Any other concerns?
 
What if I went with a 98short block or rebuild this one, although I've heard they had block problems in00 and 01in as well, and found a newer head? Would ththe newer head have the same exhaust and coil mountings as the 01best 0331? What are the casting numbers of the newer heads TUPY foundry etc. Any other concerns?

What block problems?
 
Remove and re-use ( or replace with new ) as needed or required from your original engine: Intake/Exhaust manifolds, motor mounts, throttle body, fuel injector rail, flex plate/flywheel, cylinder head, water pump, distributor-less ignition or distributor assembly, OBD engine computer sensors, fan belt driven accessories, and/or mounting brackets.

If your 2000-2001 XJ Cherokee has a cracked 0331 head, buy a good used redesigned and more durable TUPY 0331 head from a 2002+ 4.0L TJ Wrangler or WJ Grand Cherokee.*



Engine Block Casting Part Numbers:

3235444: 1980-85 CJ 258

8933002665, 53005535: 1987-1990 Renix blocks

53008405: 1991-1995 YJ, XJ, ZJ

3010341, 53010449, 53020569: 1996-1998 TJ, XJ, ZJ (except 1998 ZJ)

53020514, 53020515: 1998 ZJ

53010449AA : 1999-2001 XJ, 1999 TJ

53010327AB, 53010328AB: 1999-2004 WJ & 2000-2006 TJ
 
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I have yet to confirm all of this independently - it's all reports from the field - so take it with a grain of salt...

- There are mounting differences (block-to-chassis) between the YJ/TJ version and the XJ/MJ/ZJ/WJ version. This can't generally be swapped.
- Within models, mounting did not seem to change through the years, so they may be swapped freely.
- ANY 6-242 head can be mounted to ANY 6-242 block, regardless of model or model year.
- The 0331 head up through mid-2001 was fit only for scrap - look for a replacement with the TUPY foundry mark under the oil fill cap, this is the revised head that should last. Available late 2001-2006, this can be retrofitted in place of an early 0331 head without difficulty.
- If you "roll back" to an earlier head (0630, 7120,) know that you may need to fabricate an adapter plate to use the 0331 exhaust header with the earlier head - with each revision, the size of the exhaust ports was reduced, ostensibly to improve catalyst light-off time. The "adapter plate" would actually be a block-off, meant to cover the bits of the port that aren't covered by the primary tube entry. This may easily be fabricated using decent mild steel (I'd go at least 0.090" thick,) use the correct gasket for the head on the head side, the correct gasket for the exhaust on the exhaust side, and make the exhaust holes in the plate match the holes in the EXHAUST MANIFOLD (not the cylinder head!)
- Further, if the above is done, brackets are usually readily fabricated from sheetmetal to support the coil rail, attaching them to the screws for the valve cover.
- While the 2686 head (1987-1990) WILL mate to the block, its use is NOT recommended, due to the shift in location of intake ports for the 1991-up model years. Easier to just get a later head.

Anything further you'd like me to dig around for?

So if I understand this correctly, pretty big "if", I should hold onto the head and exhaust manifold for my '95 4.0 as they *should* bolt on to my '99 block.

By doing so I *should* be able to see some modest performance gains on the '99 due to the more freely flowing head and exhaust ports of the earlier version.

Assuming that I am correct so far in my thinking, can anyone forsee any complications from the OBDII system as a result of the head swap?
 
Shiny. Thanks! :)
 
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