Balancer Wobble Concern

[DieselD62]

Hello All,

New to this forum and to the 6.2, but not to GM light diesels.

I recently acquired a 1984 C20 6.2 and while changing headlights the other day, I noticed that the harmonic balancer has a wobble that I did not like the looks of. Upon further examination at idle, it wobbled fore/aft by 1/8" and oscilated up/down by about 1/16" I know this not to be proper, and that it can lead to catastrophic crank failure, but can anyone here with firsthand experience tell me if what I'm seeing is cause for alarm? Being without a heated garage and January, I am loathe to do any repair work outside for an extended period of time. So with that said and my plan to nurse this along until a springtime serpentine conversion, would I be wise to do so?

Regards,
Dave

[john8662]

Dave,

Welcome to TDP forums! I haven't witnessed this first hand, but the for and aft wobble doen't sound good at all. I would go ahead and tear it down, clean out the garage or borrow a garage to work on it. The harmonic balancer is going to be used on the serpentine setup either way, so you're ahead changing it now, and finding out whats the matter.

Also, does your 6.2 have a presed steel pulley attached to the harmoic balancer? If so, I'd suspect the balancer. Later model 6.2's had a dampner pulley that was a two piece design connected by rubber that would fail as you describe, maybe your engine has this?

[DieselD62]

Hi John,

Thanks for the welcome, you guys are a well organized group. I have the pressed steel pulley. Looking at it more, the outer ring of the dampner is responsible for the vast majority of the fore/aft wobble and the hub of which seems to be producing the ever so slight up/down motion. Suspect enough- it's coming out.

I thought I had the pressed pully, but wasn't positive until I saw today an '85 6.2 with the cast design. It is the style held forward of the dampner by about an inch or so?

Thanks,
Dave

[C.K. Piquup]

Welcome from another Diesel Pager.I,too,went years(12)with light GM diesels before finding this community of fellow owners and info(not myths).About that balancer,don`t let it go,you need to get that fixed soon.Do a search on balancers here.I haven`t had one fail,but seems to be fairly common.

[DieselD62]

Hello,
Just today received the new balancer (14022671) to install shortly. Can anyone tell me the size threads and legnth bolt I will need to press this baby onto the crankshaft? I'll know soon enough once the bolt in there now is out, but reason I ask is to avoid walking to the hardware store to buy one, and I know it can't be done with the bolt holding it on now- too short. No guesses- I can do that.

Regards,
Dave

[john8662]

Here is what we all pretty much do to install a balancer on these engines. Go purchase another crank bolt (or borrow one from a parts engine). Then take a longer all thread bolt (carrage bolt worked for me) and weld it to the crank bolt, and use some washers and nuts for a crank balancer install tool. Here is a picture of mine (no it's not bent):

http://members.cox.net/acmdsl/www/truck/ipstudgears/01/800x600/P1070040-800.jpg


I seriously doubt you'll find this bolt at the hardware store, I don't know the exact thread type though.

[DieselD62]

Thanks for that John,
What you've done is good if you are in a serious jam to install the balancer at 2AM and no stores are open. Even if the bolt is an odd metric size, I can get it locally, and would prefer to know the size before lifting the hood. BTW, how long is that tool you made?

[FWBennett]

Cool tool! Maybe I'm lacking some imagination.. could you please explain how the tool works?

Just a tip on re-installing the balancer bolt - I believe the torque is 200lb - I have a 4x4 Suburban so I don't know if this will work for everyone but I have a crossmember just below the balancer and found that a 4" or 6" C clamp works good for holding the balancer - the head fits in the big hole of tha balancer while the adjustable part will fit under the crossmember - I can put my torque wrench on that bolt and crank away!

[john8662]

FWBennett,

The tool is very simple, one thing I forgot to mention is the big thick washer, its the same washer used on your crank balancer already. Anyways, you start the new harmonic balancer, it will start to go on the crank (line the key up). Once you get the balancer started on, you screw the tool in the crank, bottom the bolt out just finger tight. Then install the washers and one nut. you'll use the nut to drive on the balancer onto the crank. I just use a 3/4 open end wrench. I use the tool for a long as I have threads. Then install the crank bolt and pull it the rest of the way on. Just as stated above, 200 ft. lbs torque.

[DieselD62]

Ah, now that I've just today had the experiemce of installing a new dampner, the design of your tool John no longer strikes me as odd: One cannot easily purchase a 16mm x 1.50 pitch bolt 5 inches long with full length threads. My apologies for impugning it's design as 'emergency fix'

I've also answered my own question as to the size of the bolt which is helpful for anyone wanting to make such an installation tool.

Below is a picture of the old balancer original to the engine with 141,000 miles on it. You'll note how the ring started to 'walk' off the back of the hub at various points creating the wobble.C:\Documents and Settings\Dave\My Documents\Photos\Pre-Stage\6.2Dampner5 As for the up/down oscillation mentioned in earlier threads attibuted to the hub, that I found was not the case as the old balancer removed as the new one went on: without any hint of abnormal play. The only explanation I can offer is the way the hub was machined from cast as another photo reveals the inconsistency of the hub's bevel relative to the machined face that sees the rubber which could have created something of an optical illusion. C:\Documents and Settings\Dave\My Documents\Photos\Pre-Stage\6.2Dampner3

I couldnt be happier with the new balncer's (Ebay new smile.gif )perfomance- dead-on-balls true and would recommend outright replacement of a balancer for anyone who notices even the smallest wobble on theirs. Also, front seal replacement is a given at this time. C:\Documents and Settings\Dave\My Documents\Photos\Pre-Stage\6.2Dampner2
Regards & Thanks
:cool: Dave

[DieselD62]

Why is it the pictures of the old & new balancers are not posting? can only moderators post pictures?

Dave

[john8662]

Dave,

Pictures to be posted in the forum have to be present somewhere on the internet and linked in the forum. I notice in your post that you selected images that are stored locally on your hard drive. The files are not uploaded to the forum to be viewed.

There are several ways around this, they all involve finding some webspace somewhere to upload your images and then link them here in the forum. I use free webspace (a 10mb web space) provided by my internet service provider for having cable internet. Most ISP's offer this service, its just a matter of configuring it. Another option is to sign up for an account with www.imagestation.com (http://www.imagestation.com) its a free service provided to post images on the web, was created for people with Sony digital cameras. But anyone can have an account, their service is very so-so, but it's free.

Anyone here in the forums can post images in the posts, good luck, I'll be interested in seeing your images of the balancer!! Glad that you got it worked out, I ran into the same problem, hence the tool, it comes in really handy, I didn't come up with the idea by myself either. The owner of this page (More Power) made the design and posted a picture of it on the page, I just re-created it from what I learned.

[DieselD62]

Thanks John,

See the following link for 5 pictures of the old and new balancer. http://www.imagestation.com/album/?id=2130496623
Thanks & enjoy!

Dave Little

[john8662]

Your balancer looks exactly like the one I pulled of my 86 6.2. Most of the balancers I've been pulling lately look like that, with the rubber sucked into the balancer, or, the rubber is really cracked.

[DieselD62]

Yes, the rubber appears exactly as it was when the balancer was removed at 141K miles. How many miles did you have before changing out balancers? I was of the opinion that I did not have much time left based on the way it was oscilating so as soon as the new one showed up from Texas I changed it.
One thing I noticed was the lack of holes on the outer ring of the new balancer even though the part numbers matched, I had some concerns, as I still do not know why this was done, or which balancer is the 'update'
:cool: Dave