1989 4.0 Rebuild

Hey out there, I have an '89 XJ, and its all pretty much original under the hood. Its getting to the point where front and rear seals are going, harmonic balancer too. I want and need to do a rebuild, but don't have the facility to do it or a second rig. So, has anyone out there priced a good solid rebuild or had one done? If so, any things to watch for or price estimates you can share so I know about what the damage will be? Thanks!

first, take note there are differences in the industry between rebuilt and remanufactured. Bottom line is rebuilt is minimal new stuff, and remanufactured is really gone over better and more things are replaced. to put it in a nut shell.

secondly IMO your cheapest bet is going to be to buy an entire new XJ and swap the engine over. I say this b/c i've seen XJ's for $ in the hundreds. Fully remanufactured engines IIRC are actually around $1500+ more like $1800. And junk yards, around here at least, think what they have is gold plated, and want a very high price for used parts, close to or almost to the point that you could buy it new for the same $.

or if you get lucky, find a person here selling a used engine for a sane price...

89custom said:

Hey out there, I have an '89 XJ, and its all pretty much original under the hood. Its getting to the point where front and rear seals are going, harmonic balancer too. I want and need to do a rebuild, but don't have the facility to do it or a second rig. So, has anyone out there priced a good solid rebuild or had one done? If so, any things to watch for or price estimates you can share so I know about what the damage will be? Thanks!

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Seals and harmonic balancers are maintenance items. Have you tested your compression?

Yes I have tested it, and it passed California smog tests with flying colors. After a lot of shopping around, I have found a few low mileage 4.0's for a swap and looking like $1300 for the engine, installation, as well as any needed parts when they do the work. The engine in it now is all original, and in my opinion as a guy who takes very good care of my stuff, was neglected by one or more previous owners as far as regular maintainence goes. Sucks that I get to pay for it, but I think it'll be worth it in the end..

so.....other than leaking from the front and rear, what is wrong with it? I harmonic balancer is like a 15 minute job, and seals take a little time, but the work and the parts are MUCH cheaper than an entire engine.

Just my 10 cents.

Stallacrew said:

so.....other than leaking from the front and rear, what is wrong with it? I harmonic balancer is like a 15 minute job, and seals take a little time, but the work and the parts are MUCH cheaper than an entire engine.

Just my 10 cents.

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Your 10 cents is worth thousands. I would reseal and replace the balancer if it were me.

Not to mention that since you dont have a second vehicle to use while your XJ is out of commission, you can just do this in the driveway one weekend with a standard set of wrenches and a harmonic balancer puller (which you can borrow from the parts store or buy pretty cheap).

If memory serves me correctly (or just give me til this weekend when Ill be doing it anyhow) for the front seal and the HB, you need to use the HB puller, it looks like a turkey foot, and you pull the HB (pretty straight forward). You've obviously already pulled the belt off and then you pull the 13( i think) bolts off the timing chain cover.

Then if your rear main seal (RMS) needs attention, then you pull the oil pan (before you replace the TC cover) and the 7th cap. replace that seal and re install cap (being sure to torque it correctly).

THEN you put the TC cover back on with it's seal (this way the oil pan goes onto the bottom part of the seal easier) and then the Oil pan, and then the HB (Oil pan and HB can interchange, it doesnt matter)

Then you replace the belt and tighten it........It sholud take.......4 hours?

I've never done a RMS from the bottom side, but a TC cover and HB are easy; the pan can be tricky and you just might need a few more hands....but it'll buff.

Be sure that when you remove the pan to use a gasket scraper to loosen the seized on gasket because that thing is HARD to get off and you can bend the pan lip if you arent careful.

Also, make sure ALL gasket surfaces are super cleaned off/ oil free. done use a scotchbrite, cause that would destroy an engine when inside I understand.....brake cleaner and a scraper are a good choice though.

If you have any other Q's then ask, or use the ever popular search function everyone always is raving about (I never do........just kidding, but for real it is hard to find what you are looking for on the normal search function here. I understand you can use google somehow, and I have used that before, but I dont recall how. Search for it, hahaha....good luck)

That's a basic overview of the job ahead of you, and I have condensed it and made it sound super easy (Not exactly HARD, just time consuming and in need of finese). Anyhow, I may have left out a small step here or there.

Let us know how it turns out.

cruiser54 said:

Your 10 cents is worth thousands. I would reseal and replace the balancer if it were me.

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ME as well. However when i go to replace the RMS i usually have to buy bigger tires and new rims because it all lead to installing a lift kit. And ill be lucky if i ever got the seal installed.

All that aside.You are gambling with an unknown engine.Can the person/people doing the swap gaurantee with some sort of warranty? You may be dealing with cut corners. I recently bought a used 4.0 from someone but tore it down in the garage and had it checked at a machine shop. I did have the ability to take my time though. Buyer Beware

the seals are easy and cheap. i myself would bite the bullet and change them out. look for a good rebuild candidate (not blown up or overheated) and tuck it somewhere safe and when that 4.0 ever dies (doubtful) rebuild the other one and throw it in. but thats just me. :dunno:

Stallacrew said:

Not to mention that since you dont have a second vehicle to use while your XJ is out of commission, you can just do this in the driveway one weekend with a standard set of wrenches and a harmonic balancer puller (which you can borrow from the parts store or buy pretty cheap).

If memory serves me correctly (or just give me til this weekend when Ill be doing it anyhow) for the front seal and the HB, you need to use the HB puller, it looks like a turkey foot, and you pull the HB (pretty straight forward). You've obviously already pulled the belt off and then you pull the 13( i think) bolts off the timing chain cover.

Then if your rear main seal (RMS) needs attention, then you pull the oil pan (before you replace the TC cover) and the 7th cap. replace that seal and re install cap (being sure to torque it correctly).

THEN you put the TC cover back on with it's seal (this way the oil pan goes onto the bottom part of the seal easier) and then the Oil pan, and then the HB (Oil pan and HB can interchange, it doesnt matter)

Then you replace the belt and tighten it........It sholud take.......4 hours?

I've never done a RMS from the bottom side, but a TC cover and HB are easy; the pan can be tricky and you just might need a few more hands....but it'll buff.

Be sure that when you remove the pan to use a gasket scraper to loosen the seized on gasket because that thing is HARD to get off and you can bend the pan lip if you arent careful.

Also, make sure ALL gasket surfaces are super cleaned off/ oil free. done use a scotchbrite, cause that would destroy an engine when inside I understand.....brake cleaner and a scraper are a good choice though.

If you have any other Q's then ask, or use the ever popular search function everyone always is raving about (I never do........just kidding, but for real it is hard to find what you are looking for on the normal search function here. I understand you can use google somehow, and I have used that before, but I dont recall how. Search for it, hahaha....good luck)

That's a basic overview of the job ahead of you, and I have condensed it and made it sound super easy (Not exactly HARD, just time consuming and in need of finese). Anyhow, I may have left out a small step here or there.

Let us know how it turns out.

Click to expand...

X2^^ with one addition-- I like to slip the balancer on the crank to aid in centering the chain cover before I bolt the cover home. There's not a lot of play in the bolt holes, but I've seen new seals off center and leak.

Concur - replace the FMS, RMS and HD - do it in a week-end.

Use the later (1996-up) oil sump gasket, since it's one-piece moulded rubber and will save you a good deal of wrestling while you're under there. Doesn't need RTV, either.

Opinions vary on whether to use RTV on the contact ends of the RMS or not - I don't. I've done several, and haven't had any leak. Everytime I've done one, the upper half protrudes slightly from each side of the upper saddle, so the crush is enough. Since I always soak a rear main in clean engine oil while I'm tearing into the job, that's probably what does it.

You can find my notes on the jobs here - just search around for them. It's easier than you think...

Thanks everyone! Its not that I'm not mechanically inclined enough to do this myself, the problem is that there is much, much more under the hood that was neglected before I bought the rig.. I may just do it and plug away at it one problem at a time and accomplish it much more cost effectively that way.. I'll keep everyone posted on how it turns out. Thanks again!