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Go Back JeepForum.com > Models > Jeep Cherokee & Comanche Forums > MJ Comanche Technical Forum > 87 MJ 2.5L rebuild.

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Unread 03-07-2012, 09:16 PM   #1
greaseslapper
Registered User
1987 MJ Comanche 
 
Join Date: Feb 2012
Location: worthington, IN
Posts: 38
87 MJ 2.5L rebuild.

i had a previous post "I need help! FUEL PROBLEM". it ran great for two days, but this morning i lost the fourth cylinder and could not get it to come back. I pulled the plug out and found that the plug was covered in oil residue and it was cracked. so i replaced all the plugs and wires and still had no fire. i checked the distributor it was fine. its got a new head and everything form a new coil, fuel pump, filter, new valves, rocker arms/bridges, springs. it gets way to much fuel so i think the regulator is bad. but it needs a new rear seal and i need to check the crank shaft to make sure it doesn't have movement, so im just going to take out and rebuild the motor, and fix the throttle body. is there anything else i should do while i have the motor out?

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2.5 four wheel drive.
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Unread 03-07-2012, 10:19 PM   #2
Garvin
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1986 MJ Comanche 
 
Join Date: Feb 2005
Location: Wrightstown, New Jersey
Posts: 312
Before anything, make sure the surfaces are flat. Definitely a rear main and front main for starters. Might want to think about the freeze plugs also since it's easy to get to them with the engine out. Might as well check the cam bearings also while it's out. Not sure how in depth you're going into it but honing the cylinder walls and piston rings are also a good idea, that will up the compression with new rings and will up the power some from where it is now.
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[B]1986 Jeep Comanche 126000+ miles[/B]
Long Bed, Chevy 350 TPI (5.7L V8), AX15, NP231
Roll Bar, 15/38.5R16.5 Ground Hawgs, Bastard lift (Custom 3-link long arm system, 4.5" Rusty's front springs w/ 1.75" spacers and 6.5" RC shocks, SOA rear), Dana 60HP/Sterling 10.25, 4.10's, Recessed winch, more mods to come...

[B]1992 Jeep Comanche 174000+ miles[/B]
Short Bed, 4.0L I6 HO, AX15, NP231
In the process of doing a frame up restoration.

...RIP...
[B]1990 Jeep Cherokee XJ 207774 miles[/B]
4.0L I6, AW4, NP231. Tom Woods SYE and Drive Shaft, Rusty's 8.0" Long Arm Suspension Lift, 36/13.5R15 Super Swamper IROK's, Dana 30 Front, Tube Diff Guard, Dana 44 Rear, 4.56 gears, Ox Locker, disc brake conversion
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Unread 03-08-2012, 09:07 PM   #3
greaseslapper
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1987 MJ Comanche 
 
Join Date: Feb 2012
Location: worthington, IN
Posts: 38
Im going to take and have it bored and balanced, get new pistons, crank, cam, lifters. I just replaced the frount main and balancer. im going to buy a kit so it will have all that and freeze plugs.
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Unread 03-11-2012, 07:39 PM   #4
greaseslapper
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1987 MJ Comanche 
 
Join Date: Feb 2012
Location: worthington, IN
Posts: 38
well.. i tore the motor down tt the block today. oh yeah found the problem. found out why the motor has now power and why it sounded like a diesel when its running. turns out the cam was worn OUT! and bearings were so worn that the coper layer was GONE. in one of my posts that i had i said that it smoked..... thats because the cylienders are so worn that i could move the pistons.. and i mean MOVE THEM. so boring and balanceing and buying a rebuild kit is a definite. man i drained the oil and it was full of gas so yeah a rebuild is needed.
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