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Discussion Starter · #1 ·
Well I have started rebuilding my 2.5L and thought I would start my own build thread. I am sure a lot of people are wondering why anyone would put any effort into building a 4 banger but I guess the only answer I have for that is that this will be my first complete engine overhaul and I now have 2 worn out 2.5's and a boat load of parts to play with. I would love to have a 4.0 but I don't and I really haven't been all that disappointed with the 2.5 anyways. My jeep is mainly a trail rig so I don't really need a lot of top end speed or anything. I will be taking this motor rebuild kind of slow, I am in no hurry I just want to get everything done right so hopefully I can get a ton of miles on this motor. I decided to do a complete overhaul because I bought my Jeep knowing the motor was basically shot... Had a ton of blow-by puking an oily froth into my air box. I got sick of smelling burning oil and what not so I bought a used motor and threw that in, racked up a few miles wheeling in the woods and after about a summers worth It started doing the same blow by thing and eventually spun a bearing. I guess now I just want to start with a fresh motor for this summer. I thought maybe I would start a thread about the rebuild process to share some experiences and learn some things from you guys as well.

Here is the original motor that was in my Jeep when I bought it making the trip from shed to the garage. I figured a sled would work for this:)


Getting the motor from the shed to the engine stand was enough work in itself.... I picked up this 1000 pound engine stand at Harbor Freight for $39 I am really impressed with it for the money:thumbsup:


Here is a picture of my Jeep from last summer...

I don't have any pictures of the motor tear down because of some computer problems that I was going through but I figure just about anybody could tear a motor apart anyways! The only problem I had was when I got down to sliding the pistons out they would not come out of the top because of the ridge created from many many miles and wear, so I thought no problem I will pull the crank and slide them out the bottom.... Well the piston slid right out of the bore but they will not come all the way out of the block. I didn't have a ridge reamer and I knew I wouldn't be using the same pistons so I was able to finagle my fingers in there and break the piston rings off of the pistons and slide them out the top past the ridge.

I dropped the block, head, crank and piston/rods off at the machine shop the other day. Got a call from the machinist today he said close to $700 for all the machining and parts, that includes going through the head, boring, turning crank, new timing chain and gears, cam and lifters, oil pump and complete gasket set. I guess that isn't so bad considering you can pay $400 and up for a junkyard motor.

Well that is all for now but I plan on going into a lot more detail and will be able to get a lot of pictures when I put the thing back together. I will no doubt have some questions so I hope you guys can follow along. Should get my stuff back middle of next week or so:cheers2:
 

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Good on ya for keeping the 2.5L!

I plan to keep mine, swap in an AX15, 8.8, regear to 4.88s and call it a day. :thumbsup:

The 2.5L is as capable as anything else offroad when geared correctly. The engine is easier on parts as well so less trail repairs. It really does make a world of difference on the trails.

Good luck with your build man! When my 2.5L goes I'll probably just rebuild it.

And remember... The 4banger only whines because it wants more!:2thumbsup:


Jake :tea:
 

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Discussion Starter · #4 ·
Good on ya for keeping the 2.5L!

I plan to keep mine, swap in an AX15, 8.8, regear to 4.88s and call it a day. :thumbsup:

Thanks, and yeah I am looking for an ax-15 too! I think to do the swap you need a bell housing from a Dodge Dakota?.... I think that is what it was..
 

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1)You'll need a 96-98 2.5L Dakota bellhousing. (Yeah, slim pickins on the years huh?) OR An Advance Adapters adapter plate.

2)An external master/slave set-up.

3)23 spline input shaft for your T-case. (2.5L T-cases have a 21 spline)

4)A 4.0 T-case shifter (Different size than 2.5L shifter)

5) And if you have a lift, probably new driveshafts. (The AX15 is about 2" longer than the AX5. May cause issues with stock driveshafts.)

I think that covers it all...

I have one of those bellhousings sitting on my garage floor now. Here are some pics...

Truck it came out of.


Sticker.


Bellhousing.


I hope that helps you some for future reference. I felt as if I had struck gold when I found that darn thing!

Good luck with the build my friend.:wave:

Jake :tea:
 

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Thanks Jake! I own a Dakota...Too bad it has a 318 in it!
Yeah, the 2.5L Dakotas are rare jems indeed!

I looked right past that truck probably ten times before I opened the hood looking for another part and bam! The same 2.5L engine we have was in it!


I would just keep my eyes and ears open for the parts man. As long as your AX5 isn't kicking the bucket there's no reason to buy a bunch of junk you don't quite need yet. Just keep an eye out for the parts in the junkyards :thumbsup:

Jake :tea:
 

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I like your choice. I had the original 2.5 in my '93 YJ for 109K then had to rebuild. The motor now has 238K without any issues. My advice would be to assemble the motor youself, re-check all internal clearances (shops can make mistakes too!), use plastic-gauge for bearings, feeler gauges for ring gaps, rod clearances, thrust, etc. Get a manual, it will give you the tolerances for each component. If you have any suspect parts, have it checked-out, re-do's are costly. When it comes to questionable parts, remember, IF IN DOUBT THROW IT OUT. Take your time and learn, you'll keep the knowledge forever.
 

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Discussion Starter · #11 ·
I like your choice. I had the original 2.5 in my '93 YJ for 109K then had to rebuild. The motor now has 238K without any issues. My advice would be to assemble the motor youself, re-check all internal clearances (shops can make mistakes too!), use plastic-gauge for bearings, feeler gauges for ring gaps, rod clearances, thrust, etc. Get a manual, it will give you the tolerances for each component. If you have any suspect parts, have it checked-out, re-do's are costly. When it comes to questionable parts, remember, IF IN DOUBT THROW IT OUT. Take your time and learn, you'll keep the knowledge forever.
Thanks for the advise. I am going to assemble the motor myself. I think I have a pretty good idea on how to get it all together about the only question I have is how to use that plastic-gauge stuff. Could you tell me more about that stuff? Thanks a lot.
 

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Simple: Buy the size range required for your clearance to be measured. Insert the clay strip from inside the paper in between the crankshaft journal and the bearing cap with the bearing installed. Torque to spec. Don't move the crank! Then just remove the cap/ bearing and compare the width of the clay strip to the markings on the paper. Repeat this for each crank journal and also check each rod bearing clearance. Don't forget to use feeler gauges for checking the side clearance of the rods and the thrust clearance on the crank.
 

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Discussion Starter · #15 ·
Anybody know if any certain ring compressors are better then any others? I heard of some that are more or less just like a sleeve that is made for your particular bore but I don't know if I can find one of those. My motor is getting bored 60 over. I had concerns about taking it this far but the machine shop said no problems at all.
 

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Ring compressor that has worked for me and is in expensive Google Image Result for http://www.comparestoreprices.co.uk/images/sy/sykes-pickavant-piston-ring-compressor-medium.jpg
I wouldn't worry about a ring expander. The rings can be spread apart over the piston top, twist slightly, place one end in the desired groove and gently lace the rest of the ring into the groove. The important thing to remember is to avoid dragging the rings over the piston, creating nicks or scratches in the softer aluminum. If you do accidentally scratch the piston, use a de-burring pad to clean it up. Install the oil rings first, then work up the piston. Before doing all this, place each ring in the cylinder you will ultimately have it in, and verify the end gap. Don't worry about the oil rings, these gaps are huge.
 

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< I am sure a lot of people are wondering why anyone would put any effort into building a 4 banger

original intention for the Jeep was a light 1/4 ton recon vehicle to replace the horse and mc. V8 hollywood image saturated the popular press like so much BigFoot killer truck propaganda.

the beauty of a 4 banger is the minimum weight. true you can't wisk a loaded trailer up interstate hills with the same verve and bravado, but that's why God invented big trucks... and why folks put truck axles on their V8s when they tear up spyders.

if everyone wanted a Harley, there would be no dirt bikes...a knife to the heart.

the Jeep as it was intended to be was an American VW Bug. (not a penile extension to swash around in public)

gearing up for social collapse and $4+/gal. gas, I personally want a faithful little mule, not a feed sucking show Clydesdale.

the power junkies can have their fun with my blessing, but when it all comes tumbling down (shouldn't be too long now) I'd want to land on my feet under the radar.

you won't sell that argument to the consuming masses, so don't even try...but there's a jewel of wisdom hidden in the fabric of the original military spec.
 
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