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1988 4.0L Renix Rebuild

avnsteve

NAXJA Forum User
I'm tearing down a renix to rebuild. I have pix of what I've done so far and will post them soon. If anybody wants to ask any questions along the way, just let me know what you need. Also, and more importantly, anyone that wishes to offer any tips and or guidance, I'll be posting my questions up on this thread as well. I'll be sending out the block, crank, cam, and head to a machine shop for clean up and inspection. It doesn't appear that the block has been bored and you can still see the marks on the cylinder walls from the last honing, let's hope everything else is good too. My intention is to rebuild it as perfectly stock as possible, not a stroker or HO. I figure it was good enough for 200k miles, why not go for another 200k...
 
I have one that was running fine when it was pulled at 167,000 miles that I had shipped down from Wisconsin recently. The owner replaced it with a V-8, stored it for 3 years planning a stroker, but then he sold it to me. I am planning to do a partial tear down, cleaning, inspection and replacement of all the seals and gaskets at a minimum. Not sure how far I will go but not planning to go the full route like yours. I will be watching for your posts.:cool:

May upgrade and replace a few things like the oil and water pump while they are easy to get too!
 
I pulled mine and took it to a local race/machine shop to get a complete rebuild. The only thing I re-used was the block, crank, valves and head. They assembled the motor after all of the machinening and pressured it up. They punched it out 40 over, decked the block, milled the head, and reworked the valves.

$1700 total and 1 year 12k warranty.

I'm a mechanic and could do it myself but hey 2 weeks later I was driving it.

The head
dadsjeep35dg.jpg

engine assembled
engine1bt9.jpg

engine2wb9.jpg
 
Man, oh,man, That looks nice!!!!!

Just a quesion. Why didn't you go with a after market exshaust header?
That would reallly look great and run nicer with all the work you did to the engine?

Still, looks great.

Pigpen
 
that's xjtrailrider's engine in the pics, i haven't posted mine yet, but I am using stock because that's what i have, and upon inspection, there's no cracking, nor warping, so penny saved... I do plan to have the exhaust coated (ceramic) to help keep temps down in the bay a little...it's only about $100 here locally from what i understand
 
Pigpen said:
Man, oh,man, That looks nice!!!!!

Just a quesion. Why didn't you go with a after market exshaust header?
That would reallly look great and run nicer with all the work you did to the engine?

Still, looks great.

Pigpen
Yes that's my daily driver that I am doing a resto-mod on. Its basically stock(4.0,AW4,NP231), but it will get a few goodies which include 3.73 gears, a 29 spline 8.25, posi-lock front disconnect, and HD rear springs and a spacer in the front to level it. I already have a HD tranny cooler, tranny temp gauge, and a few other goodies. It runs good enough I don't need headers. I still run the stock manifold in all of my XJ's, I've found that the money is better spent other places. But everyone has a different opinion.

I have 4 XJ's so I wanted one of them to be nearly as stock as I could allow myself to go. This 90 used to be my Dads that he bought brand new, he passed away a few years ago so it is a tribute to him.

Some before and after shots
dadsjeep21ob.jpg

dadsjeep6su.jpg

I also replaced all of the RENIX input/output sensers/devices etc. and the fuel injecters/pump, distributer, pressure regulator, if you can think of it it is new under the hood or under the Jeep.

Here is another shot of the finished motor, I've got 8k on it now, it runs great.
90engine1dl8.jpg
 
Last edited:
avnsteve said:
that's xjtrailrider's engine in the pics, i haven't posted mine yet, but I am using stock because that's what i have, and upon inspection, there's no cracking, nor warping, so penny saved... I do plan to have the exhaust coated (ceramic) to help keep temps down in the bay a little...it's only about $100 here locally from what i understand


I live a few hours south of you and can not find a ceramic coater here can you post or PM me with a name and contact info?
 
avnsteve said:
I'm tearing down a renix to rebuild. I have pix of what I've done so far and will post them soon. If anybody wants to ask any questions along the way, just let me know what you need. Also, and more importantly, anyone that wishes to offer any tips and or guidance, I'll be posting my questions up on this thread as well. I'll be sending out the block, crank, cam, and head to a machine shop for clean up and inspection.

I'm going through the same thing as we speak. I have a '90 motor I am going to rebuild for my '88 Laredo. Family and friends (who can afford new cars every two years) ask me why I am bothering with an almost twenty year old vehicle, and I reply with "Because I CAN!!!". Sure beats sinking into a couch watching American Idol with potato chip crumbs all over your belly...
Good luck with your project, have fun and take lots of pictures as you go. Lets us know of any good tips you discover along the way!
 
When you guys have your engines apart like this, and are ready to shell out $8K (quoted from xjtrailrider) - why not port and polish the cylinder head? There is more power than you can imagine to gain from that (from what I've heard the stock heads are pretty restrictive).
 
NXJ said:
When you guys have your engines apart like this, and are ready to shell out $8K (quoted from xjtrailrider) - why not port and polish the cylinder head? There is more power than you can imagine to gain from that (from what I've heard the stock heads are pretty restrictive).

My rebuild is an exercise in Keep It Simple. Once I install this BONE STOCK engine, and run it, I'll probably use the other one to build up a stroker, I may or may not install it, but will definitely build it
 
Daddycajun117 said:
If I wanted to do a basic rebuild, what kind of parts would I need and about how much would it cost. I have an 89 XJ 6cyl with 193K

I did some shopping on Ebay, got a "master rebuild kit" for $400 on a "make offer" deal (comes with a lot of stuff, mostly bottom end), a reground crank with matching bearings for $99, and some specialty tools. Going to have to spend some money at a shop to, at the least, get the new pistons pressed onto the rods and the cam bearings pressed into the block. Add in the engine stand and crane I brought, along with the u-pull-it engine, I am just about at $1000.
If all else is okay, the rest is all blood, sweat and knuckle skin. I know the money goes out quick on a project like this, and it can get close to the cost of a purchased rebuilt, but for me it's a hobby. My current engine is getting me around for now, so I am not pressed for time (fingers crossed).
 
Not to hijack your threadbut, I need to get my head done, 88 4.0L, nothing really wrong just wanna port and polish it, valve job and get it cleaned up. About how much should this cost me at a machine shop? Assuming I pull the headmyself and replace the rocker arms, springs and the rest?
 
1985xjlaredo said:
Not to hijack your threadbut, I need to get my head done, 88 4.0L, nothing really wrong just wanna port and polish it, valve job and get it cleaned up. About how much should this cost me at a machine shop? Assuming I pull the headmyself and replace the rocker arms, springs and the rest?

i have a quote from a shop here in Austin that will take my filthy head and vat it, magnaflux for cracks, and install new stems guides and seals etc for $200...
 
avnsteve said:
i have a quote from a shop here in Austin that will take my filthy head and vat it, magnaflux for cracks, and install new stems guides and seals etc for $200...

Same thing here in my town was $150, thats if the valve guides are good and with a basic valve grind, no 3 angle stuff.
 
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