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  #1  
Old January 11th, 2019, 07:59
seanof30306@yahoo. seanof30306@yahoo. is offline
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Difference Between '96 and '97 Short Blocks?

OK, so I overheated my '96 XJ so bad it cooked the short block. #2 cylinder has only 20 lbs of compression and the walls are scratched to hell. Guess the rings are broken. #3 only has 40lbs, and I'm pretty sure the block is warped; it keeps blowing the head gasket between #s 3 and 4.

I can get a new '96 short block (pn 4798788) for $2,158.20. I can get a new '97 short block (pn 4883025) though, for $1,716.15. $440 would be a big savings, if it will work.

Will the '97 short block bolt in? Is everything the same?

Thanks,
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Old January 11th, 2019, 08:14
seanof30306@yahoo. seanof30306@yahoo. is offline
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Driveability Differences Between 0720 and 0331 Head?

OK, so the heater valve disintegrated on my '96 XJ with an 0720 head while I was driving down the highway. I didn't notice until it started skipping like hell. I scanned the gauges, saw the temp gauge was PEGGED and went to pull over. It shut off and wouldn't start. Wasn't locked up, just wouldn't start. Let it cool down and it started, but it was running rough.

I knew the head was cracked. Pulled it off and sure enough, it was.

Looked the block over and it seemed OK. Put WD40 in each cylinder overnight, and it didn't leak into the crankcase.

The only thing I could lay my hands on was a remanufactured 0331. This Jeep is a street-only vehicle, and is getting ready to just become my backup/bad weather driver, so I wasn't overly concerned about the smaller ports.

It ran perfectly with the new head, except it appeared to be down on torque. I take the same highway to and from work every day. With the 0331 head, the kickdown was engaging on slight to moderate inclines it never had on before.

I chalked it up to the head, but it now has a blown head gasket, 20 lbs of compression and serious scratches in #2 cylinder, and 40 lbs of compression and water leaking into #3.

Obviously, that overheat cooked the shortblock too.

I'm going t put a new shortblock in it. I need to decide what to do about the head. Do y'll think the driveability issues I saw after putting the 0331 head on were from the small ports in the head, or the damaged short block?

Thanks
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  #3  
Old January 12th, 2019, 07:07
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cruiser54 cruiser54 is offline
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Re: Difference Between '96 and '97 Short Blocks?

Quote:
Originally Posted by seanof30306@yahoo. View Post
OK, so I overheated my '96 XJ so bad it cooked the short block. #2 cylinder has only 20 lbs of compression and the walls are scratched to hell. Guess the rings are broken. #3 only has 40lbs, and I'm pretty sure the block is warped; it keeps blowing the head gasket between #s 3 and 4.

I can get a new '96 short block (pn 4798788) for $2,158.20. I can get a new '97 short block (pn 4883025) though, for $1,716.15. $440 would be a big savings, if it will work.

Will the '97 short block bolt in? Is everything the same?

Thanks,
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)
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  #4  
Old January 12th, 2019, 07:08
cruiser54's Avatar
cruiser54 cruiser54 is offline
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Re: Driveability Differences Between 0720 and 0331 Head?

Quote:
Originally Posted by seanof30306@yahoo. View Post
OK, so the heater valve disintegrated on my '96 XJ with an 0720 head while I was driving down the highway. I didn't notice until it started skipping like hell. I scanned the gauges, saw the temp gauge was PEGGED and went to pull over. It shut off and wouldn't start. Wasn't locked up, just wouldn't start. Let it cool down and it started, but it was running rough.

I knew the head was cracked. Pulled it off and sure enough, it was.

Looked the block over and it seemed OK. Put WD40 in each cylinder overnight, and it didn't leak into the crankcase.

The only thing I could lay my hands on was a remanufactured 0331. This Jeep is a street-only vehicle, and is getting ready to just become my backup/bad weather driver, so I wasn't overly concerned about the smaller ports.

It ran perfectly with the new head, except it appeared to be down on torque. I take the same highway to and from work every day. With the 0331 head, the kickdown was engaging on slight to moderate inclines it never had on before.

I chalked it up to the head, but it now has a blown head gasket, 20 lbs of compression and serious scratches in #2 cylinder, and 40 lbs of compression and water leaking into #3.

Obviously, that overheat cooked the shortblock too.

I'm going t put a new shortblock in it. I need to decide what to do about the head. Do y'll think the driveability issues I saw after putting the 0331 head on were from the small ports in the head, or the damaged short block?

Thanks
Do it right and get the correct head.
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  #5  
Old January 12th, 2019, 07:11
cruiser54's Avatar
cruiser54 cruiser54 is offline
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Re: Difference Between '96 and '97 Short Blocks?

Also Sean, you are the poster child for eliminating that worthless POS heater valve. It's unnecessary and can cause catastrophic losses of coolant.
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  #6  
Old January 12th, 2019, 14:25
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Tim_MN Tim_MN is offline
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Re: Driveability Differences Between 0720 and 0331 Head?

Quote:
Originally Posted by cruiser54 View Post
Do it right and get the correct head.
What he said.
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Quote:
Originally Posted by bimmerjeeper

I'm starting to realize people on the Jeep forums are highly expert mechanics .....
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  #7  
Old January 12th, 2019, 15:47
seanof30306@yahoo. seanof30306@yahoo. is offline
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Re: Difference Between '96 and '97 Short Blocks?

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Originally Posted by cruiser54 View Post
Also Sean, you are the poster child for eliminating that worthless POS heater valve. It's unnecessary and can cause catastrophic losses of coolant.
Yes it can!!!!

lol
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  #8  
Old January 12th, 2019, 17:47
Mr.Smith Mr.Smith is offline
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Re: Difference Between '96 and '97 Short Blocks?

I believe the Only difference between the two blocks should be a temp sensor port on the drivers rear top of the head on the 96 that will not be present on the 97, as the two sensors (thermostat and gauges) became integrated. Can be worked around pretty easy. If for some reason your 96 didn’t have it on the back of the head then they are the same. Good luck.
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