Big bang, now metal "rattling" sound...yikes!

[stiffler4444]

Hi all,

Yesterday I was taking my Pinz to work, driving a nice 50km/hr...and suddenly BANG..like a shot was fired at me and then a loud sound under my feet like a hammer tumbling in a dryer!
I immediately pulled over and got out to check for damage. Nothing physical was noted, and the engine was purring smoothly.
I was in regular 2 high and under no load.
My only guess, before I start tearing things apart, was my front drive shaft u-joint might have busted? What are your immediate thoughts? I drove the remaining 2 km's to work. The noise is definately speed related (i.e. the slower I go, the slower the "banging and rattling"), and does not affect normal 2wd operations.
I know I need to address this before it goes any further, but thought I'd throw this out for a few speculative guesses at where to start....

Drive shaft/u-joint?

tx Dave

[berger]

Is there any slop in the shaft or u-joint?

[stiffler4444]

Hi,

Haven't had time to look at anything outside of the obvious (fanbelt and underside). Will be doing so this weekend. It sounds and to me suggests it would be the ujoint. But it is definatley much more than loose.....

tx Dave

[undysworld]

Dave,

From your description of a big BANG, the first thing that comes to mind was when my alternator fan blew up. Although if that happened, I'd think your alternator light would illuminate, and it doesn't explain the hammer tumbling noise. If the fan blew up, you would see the damage through the front air tunnel.

FWIW, there are no "U-joints" in the front driveshaft. The only U-joints are in the propeller shaft which links up the tranny and the transfer case. If they let go, you wouldn't be moving anywhere, either in 2wd or in 4wd.

I'm guessing you did not notice any braking problems, or else you would have mentioned it. So I'll take a guess that the brakes are not the cause.

Which leaves me suspecting your front differential somehow suffered an internal failure. I'll assume it's properly filled with fluid?

Maybe try a few things:
Get it on a hill, and with the engine off, start rolling. If the banging occurs, it's not engine-related.
Jack the front axle off the ground, and engage the #3 locker (which should lock the front diff side-to-side). If the wheels do not turn the same direction together when you move them, the problem is likely in the front diff.
Then engage the #1 locker and set the parking brake. If the front tires can still spin, I'd be suspecting the front drive shaft or other internal parts within the torque tube.

[pinzinator]

I'm going to guess the differential failed. This is an example of why the Execution II kit should be installed.

[Jimm391730]

I'm going to guess the differential failed.

My guess too. The bevel gear shaft (which is what Execution II improves) problaby let the gears go, and they are bouncing around between the crown gears ("hammer in the dryer sound"). This would be very bad for the crown and pinion gears, I wouldn't drive it at all until you can drain the diff and look inside through the drain hole; you should be able to look straight up to see the main drive shaft, bevel gears, and bevel gear shaft ends. Or see that they are missing... or they block the drain hole so you can't see a thing!

Best of luck,
Jim

[stiffler4444]

Hi all,

Thanks for the responses......it has gone to that dark place I hoped it wouldn't go....but I did think of the front end gears as well.

Ok, well, next is to jack it up and have a look. Can't be good....oh no...can't be good........

[pinzinator]

Parts are available. Just hope the case hasn't been damaged. With some good jack stands and a floor jack you can have the differential out in a couple hours or so.

[stiffler4444]

Parts are available. Just hope the case hasn't been damaged. With some good jack stands and a floor jack you can have the differential out in a couple hours or so.

Sounds like a Saturday project to me. I the meantime, I'll start looking at parts/$$$, just in case it is the gears. And yes, I hope there is not too much collateral damage....

[berger]

Parts are available. Just hope the case hasn't been damaged. With some good jack stands and a floor jack you can have the differential out in a couple hours or so.

Sounds like a Saturday project to me. I the meantime, I'll start looking at parts/$$$, just in case it is the gears. And yes, I hope there is not too much collateral damage....

If you were closer, I would love to help you out with this....if it is the problem. Here's opening it ain't!

[stiffler4444]

Boy, do I wish you were closer too!!! Thanks for the willingness, you are far more eager than I am...

At any rate, every repair is an opportunity to learn......but some learning experiences are far more expensive than others.

I guess I presumed that if I buggered the gears, the vehicle would either lock up or drive as if it was chewing up some metal.....she moves smooth, with the horrible sound being the only evidence of a disorder...

But then again, I have not tried to engage the front locker......

Dave

[undysworld]

you can have the differential out in a couple hours or so.

I think this is an optimistic goal, especially for the front diff. But to be honest, I've not yet had to pull my front. But I don't want to be a killjoy, if others know more than I.

Nevertheless, I'd allow more time, just in case, and especially if you've never done it before.

[pinzinator]

It could take a long time, depending on tools and mechanical aptitude. Here is a good link on how a Pinzgauer differential works, the small gears in the center are what broke-

http://www.youtube.com/watch?v=G9wNbXZf ... re=related

[stiffler4444]

That's a great video, gives me a good idea what I'm looking at. Never had a case open before on a Pinz.

tx Dave

[milesdzyn]

A bore scope is the way to go before pulling the front diff assembly, just remove the top plug with the ring on it and inspect with the bore scope first. Best investment in a tool I ever made.

Miles