How to tell if Harmonic Balancer is bad??

[cywagoneer]

Riding in the jeep feels like an $80 massage, I suppose its a bad thing right? Before I change it out with one I have lying around, is there an easy way to tell if its bad? I know the carb needs tuned and I haven't found any obvious vacuum leaks. The shake is noticeable in P, N and D, although more noticeable in D.

This board is getting busy isn't it? Seems like we can get two pages of posts in one day. I guess it's a testament to the knowledge of the posters here.

Thanks.

[jode]

I think you are barking up the wrong tree. How can a balancer go bad unless the rubber gasket either breaks or allows the outer ring to slip? If it completely comes apart, it is easy to tell that is the problem by inspection (visual) plus the ring that is separted will bang and clank around as the engine turns. I have had one break (the outer ring was COMPLETELY disconnected from the engine on my 401) but for it to slip without coming completely apart doesn't make any sense to me.
You might wnat to try to isolate a different problem.
However, s'posing your balancer was, indeed, bad, you should be able to see if the rubber was cracked by a visual inspection with a good flashlight. Also make sure that there aren'tsigns of any sort of cracking or anything.
just my humble opinion.

[Crazy_Jeepman]

We should isolatewhen the vibration occurs, if it happens only when driving then it will be a driveline issue. If it is vibratting when at idle then it would be a engine balance problem, such as harmonic balancer, broken flexplate, or torque converter. I have seen the outer ring of a harmonic balancer spin and not come off. It is very possible to have happen. This being the reason high $$$$ balancers are available for race cars. ;)

[cywagoneer]

I think it is an engine balancing issue. At idle in Park the entire vehicle shakes. It is not nearly as noticeable once you are cruising along, but once you stop at a light it's there again, very rough idle, I usually put it in Park again just so it doesn't shake quite as bad. I just put a different(used) engine in and it's been like this from initial start-up.

So you think balancer, flex-plate or torque converter. I can take a look at the flex plate and see how it looks along with the balancer. What is a good way to check the converter. I am not leaking any fluids and the tranny shifts smoothly.

I have an Olds with the 3.8L and when the balancer went bad it did not fly apart. Infact without the serpentine belt running the accesories you wouldn't have even noticed it was bad. It did get progressively worse over a couple of days before I had it replaced.

[porkchop]

What do your engine mounts look like? Another thing to check is the vacum line that comes off the intake and runs your brakes. When it is in park there is a small leak and then when you step on the brake it draws more vacum which causes it to shake more in drive with your foot on the brake. This happened to me and it ended up being a crack line to my brake booster. These are just a couple easy things to look at.

[gbarrett]

I had a torque converter do that once. One of the weights came loose. At idle, it felt like it was shaking apart, but at normal driving speeds, it kinda smoothed out.

[RichCal]

If its really an engine balance problem, you'll have a smooth barely-pulsating flow at the exhaust pipe, even when the shaking is the worst.
Do you?