• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

destructive harmony

9

98XJ40231

NAXJA Forum User
Location
New Berlin, IL
Has anyone on here with the 4.0L ever had their harmonic balancer come/almost come apart? Mine started off about a month ago throwing the accessory belt. Then about 2 weeks ago, it did it again, then for the third time again today... going about 70 m.p.h. so i was like "oh, simple fix, the tensioner come loose again" cuz that's what i originally thought it was. well, as i'm trying to get my back-up belt on since it ate the one that was on it :smsoap:, one of my classmates (who drives a 95ish XJ with the 2.5L) stops to help me... well we get it back on, and i fire it back up and it immediately throws it again so we both like "well... f$*&" get to lookin and he notices that the balancer has slid forward and that was what was causing it to slip the belt... we get it to school (semi-legally) and after class and about 3 hrs. and almost $100 later it's fixed and running like new :cheers:
 
While having a failed HB isn't rare, it seems to happen quite often on 4.0 engines in my experience.
 
Matthew Currie said:
Have you noticed any change in later years? When I first started on the old XJ forum, it was a very common subject, but one seems to hear about it less these days, so I'm just wondering if they improved the rubber or something.
Click to expand...

Maybe they stopped using the crappy rubber insert and just made it a solid pulley... i don't see why they couldn't... and what makes it better is that i replaced that and it also solved the vibration at highway speed... party1:
 
98XJ40231 said:
Maybe they stopped using the crappy rubber insert and just made it a solid pulley... i don't see why they couldn't... and what makes it better is that i replaced that and it also solved the vibration at highway speed... party1:
Click to expand...

It wouldn't be a "harmonic balancer" without the rubber. It would just be a pulley. The rubber dampens the harmonics.:doh:
 
cruiser54 said:
It wouldn't be a "harmonic balancer" without the rubber. It would just be a pulley. The rubber dampens the harmonics.:doh:
Click to expand...

Exactly.

There are solid units used in some racing/marine applications, and you can always make a solid with the judicious application of a drill and screws/bolts, but that isn't something I would do.
 
On big trucks the balancers appear to be solid but they have a floating ring in some kinda fluid "inside" the dampener. I suspect some of the racing dampeners do too.
 
cruiser54 said:
It wouldn't be a "harmonic balancer" without the rubber. It would just be a pulley. The rubber dampens the harmonics.:doh:
Click to expand...

true, but if i remember correctly, the harmonic balancer is just a weight on the end of the crank that smooths the vibrations out... similar to a wheel weight kinda... correct me if i'm wrong. but like the small-block chevy V-8's just have a weight with no rubber and then the pulley bolts to the HB via 3 bolts... again no rubber... but like i said, somebody correct me if i'm wrong about the HB...
 
A suggestion: A quick 'net search will explain how the various forms of harmonic balancer work. The complex harmonics developed by an internal combustion engine in operation are very different from an out-of-balance wheel.
 
Pelican said:
A suggestion: A quick 'net search will explain how the various forms of harmonic balancer work. The complex harmonics developed by an internal combustion engine in operation are very different from an out-of-balance wheel.
Click to expand...

Correct. And each engine's harmonics have to be dealt with in different ways.
 
98XJ40231 said:
true, but if i remember correctly, the harmonic balancer is just a weight on the end of the crank that smooths the vibrations out... similar to a wheel weight kinda... correct me if i'm wrong. but like the small-block chevy V-8's just have a weight with no rubber and then the pulley bolts to the HB via 3 bolts... again no rubber... but like i said, somebody correct me if i'm wrong about the HB...
Click to expand...

Small block Chevy does have a rubber ring separating the inner hub and outer ring.

I sure would like to see Fluidamper make a damper for the 4.0.
 
I'm starting to suspect mine might be on it's way out. From those with experience, can a failing HB lead to some vibes only at idle? That is the only trouble I've had with mine. Last time I looked, everything looked intact, but the rubber is getting old and starting to look dry and cracked. I think I read somewhere that the rubber may start to poke out a bit from the face of the pulley when it starts to let go and the new one in those pics looks like that may be true.

I'd like to replace it now if it needs it. Don't want to have it fail on the road or trail. It's a 93 4.0 BTW.
 
american_zero said:
I'm starting to suspect mine might be on it's way out. From those with experience, can a failing HB lead to some vibes only at idle? That is the only trouble I've had with mine. Last time I looked, everything looked intact, but the rubber is getting old and starting to look dry and cracked. I think I read somewhere that the rubber may start to poke out a bit from the face of the pulley when it starts to let go and the new one in those pics looks like that may be true.

I'd like to replace it now if it needs it. Don't want to have it fail on the road or trail. It's a 93 4.0 BTW.
Click to expand...

Go for it. Rent a puller--the smaller ones you don't have to pull the radiator. If it doesn't come with an installation tool buy yourself a longer-than-stock bolt with a handful of washers. Grease up the washers on the longer bolt and use that to get the HB started on the crank, then remove the bolt, remove a couple washers, tighten it up some more, remove a couple washers, etc., repeat until the stock bolt can be used and properly torqued. Greasing the washers reduces the effort required. Beating the HB on or trying to start it with the stock bolt are not very good ideas.
 
I've never felt vibes from a bad dampener. What it's dampening probably wouldn't be detected by a human. Look at the rubber between the two pieces. Cracked, falling out? Replace it. They're only $44 at Napa and had a high failure rate. As for your vibes, look elsewhere like motor/trans mounts, exhaust contacting crossmember etc.
 
You must log in or register to reply here.

Similar threads

Bent
Contrary to what a lot of people believe...
Replies
3
Views
123
JohnX
JohnX
M
92 XJ ECU connector
Replies
5
Views
137
Rob Mayercik
R
R
thinking about getting an XJ again
Replies
9
Views
278
XJI6191
X
Root Moose
Cooling System Reset (2000 XJ)
Replies
1
Views
1K
Rob Mayercik
R
C
Seat repair
Replies
4
Views
1K
Glasply
G
Back
Top