Replacing Harmonic Balancer

1987 4.0 138,000 miles. Harmonic Balancer is shot, rubber coming out and hitting the fan, slinging oil. I'm planning on replacing it this weekend. NAPA price $48.49 (Dealer was almost $200 !) also Napa has a "Kit" with the front main and timing chain cover gasket for $21.49. Is this everything I need?

I'm planning to check the timing chain for slop when I'm in there but these have been easy miles (no towing or off-road use) so I'm not planning on replacing it.

Read the forums, gonna try it with the radiator in place. Thanks for feedback.

You'll need a puller.

3XJFamily said:

1987 4.0 138,000 miles. Harmonic Balancer is shot, rubber coming out and hitting the fan, slinging oil. I'm planning on replacing it this weekend. NAPA price $48.49 (Dealer was almost $200 !) also Napa has a "Kit" with the front main and timing chain cover gasket for $21.49. Is this everything I need?

I'm planning to check the timing chain for slop when I'm in there but these have been easy miles (no towing or off-road use) so I'm not planning on replacing it.

Read the forums, gonna try it with the radiator in place. Thanks for feedback.

Click to expand...

Why bother the timing chain and cover? If the seal isn't leaking, leave that be too. Puller can be fab'd very easily. Break the crank bolt loose with a long wrench/break-over bar braced properly and bump starter. Rad can stay in place too. Timing chain is long life item, I'm still on the original +260k miles.

"slinging oil" w/138k is not a good thing.

I assume this is from the front only?

the puller recomemendation is a must

NAPA gasket kit SHOULD include crank seal in the TC cover. IF (and I do mean IF) the TC and gear set needs to be replaced at 138k, don't bother to stop with that, the engine is toast.

Are you leaking out the back as well?

Have you used any oil "leak sealers" ? These start your engine on a down hill slide.

Yeah, figured I'd need the puller. It's a strong engine with no noise, and good oil pressure and no leaks from the rear main. I can see where oil has been slung across the inside of the hood in a line which appears to have come from the front of the engine. . . figured it was the front main from what I've read - same as the crank seal? just haven't got in there to look where the oil is coming from but figured the balancer was wobbling and wore out some seal. . . .

OK, I am guessing that the seal behind the harmonic balancer should be replaced since there is some sort of oil leak which appears to be coming from behind it. . . Enough of a leak that the fan has obviously sprayed it onto the hood insulation. My instinct tells me that it won't go away by replacing the harmonic balancer. Right?

I have a tendency to save money by doing it myself, then blow it all on extra parts, "while I'm in there". . .

Do I need to remove the TC cover? I looked in the manual last night, and that certainly makes it more of a PIA. . .

If I have to pull the TC cover to replace the seal. . . It is as good a time as any to Pull the radiator . . . Replace the front seal, TC gasket and balancer. . . Then, convert from an open to a closed system, (I have a spare 3-core open-style radiator) flush and new hoses. I've been putting off this job. . . see what I mean about "while I'm in there". . .

Gonna make a parts run at lunch today. Opinions? Experience?

You don't understand, the part that's wobbling isn't bothering the seal. Removing the TC cover and radiator is not REQUIRED. Remove bolt, pull balancer, pry-out old seal, drive-in new seal, install new balancer/pulley. Don't overtighten the serpentine belt. Done.

XJXJ said:

You don't understand.

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Exactly! Thanks for making it clear. As soon as I mentioned a seal to NAPA, the wanted to sell me the kit with the TC gasket, so I thought the TC had to come off! I didn't know to call it a crank seal so they were trying to sell me a front main. . . I understand now.

I knew it wasn't necessary to remove the Radiator BUT the cooling system is due for a service AND I want to convert from the old style open system to a closed system SO, doing that at the same time would have made working on the front of the engine less unpleasant.

At that age a radiator is probably due because of scale buildup reducing the cooling capacity. I don't "believe" in the need for the closed/open conversion but since you already have the open rad, might as well use it. Of course, you'll get to re-plumb heater valve, source and mount an overflow bottle, and sort-out something for the e-fan sensor/switch. 'Never been worth it to me.

Don't forget to qualify and probably change the motor mounts if you do the rad. Slightly thicker unit can create clearance issues with the engine fan/clutch if the mounts are sloppy. Possibly severe damage if overlooked.

More room is good but it's not that bad either way. Find some bolts that thread into the hub of the old pulley and you can make a puller very easily with a piece of steel and some drilling. Lube the bearing surface of the new balancer/pulley with motor oil before installing. Loc-tite on the crank bolt isn't a bad idea either.

Remember what I said about overtightening the belt. If you're inexperienced, use a tension gauge/tool or risk damage to engine accessories and possibly your new balancer/pulley.

My opinion is to replace the seal. The Harmonic balancers sealing surface probably has worn a groove with that many miles. Since you are replacing the HB, then the regular seal kit should do. They do make one to cover the grove on the HB. As I remember you have to pull the seal out and align the TC cover to the crankshaft. A proper sixed socket works, but I can't remember exactly what I used. The kit also comes with some tab gaskets to lpace on the oilpan. I think at that kind of age, milage and that your HB has started to come apart, that your seal is more than likely damaged. Better to replace it, while you've got stuff apart. As you stated, also a good time to check the timing chain. They can go bad. The Jeeps all metal to they last longer. During the 70's, most manufactures used a plastic toothed main gear. These wore quickly. Still, it don't hurt to check. Good time to replace the thermostat. Get a Roberts Shaw or Mr. Gasket. Also, since you are doing the Radiator conversion, check out the Cherokee America site. They have some info on wiring the change in sensors. They also have a link to another site, that makes it work like originally. Also, in another thread, you mentioned Blow-Bly. That can put oil everywhere. Although you didn't say it applied to this vehicle.
Tom
Tom

What is the best method to re-install the balancer?

Tom,
I picked up the HB, puller, and a seal (which apparently doesn't require removing the TC) at lunch. I can check for slop by rotating the engine, and only if there is a problem am I planning to pull the TC. If it is easy enough to get at with the puller, I'll probably save the Radiator project for another weekend. I've used Cherokee America as an info source in the past (though I wish they would remove the old article on the 3" Pro-Comp lift - from experience, it sucks, I have thrown most of the components in the trash over the last year and replaced with OME). This one is starting to have a little blow-by which I will address soon. . .

XJXJ,
Thanks for the advice.

lumberxj89,
Installation of the HB is pretty straight forward, use the nut to tighten it back down, Do not drive it on.

Don't use the stock bolt to push the balancer back on unless you want to risk striping out the threads in the end of the crank. You either need the right tool or use a longer bolt with a nut and greased washers. Screw the long bolt in and then turn the nut to push it on.

What tool would you use to install the HD ?

Never mind my last post ... I didn't read the one above very well. Ok, longer bolt with a nut - pull the new HB up with the nut. Thanks much !

ssnsltd said:

IF (and I do mean IF) the TC and gear set needs to be replaced at 138k, don't bother to stop with that, the engine is toast.

Click to expand...

That's the worst advice I've ever heard. I'd love to know why a bad timing chain means the whole engine is "toast"

Replace the balancer and crankshaft seal. If it's slinging oil, that seal is leaking. No reason to replace what ain't broke, so don't remove the timing cover or replace the timing chain, and I see no reason to replace the radiator at this point either.