Now I wonder what's going on !!!

I'm happy to report that this vehicle is no longer making any noises except for wind noise and tire/road noise!

I had read that before taking a U-joint apart it's necessary to mark it so it goes back in the same way it came out for the drive shaft to remain balanced (i.e. there is a balancing weight welded to one side of the shaft). I did not read the same about the spline end of the drive shaft that goes into the transfer case and since the spline seems to be uniform around the shaft I did not think that made a difference. Obviously neither did the technician at Firestone because there was no mark there even though he had chalked a mark at the rear U-joint when he replaced that.

When I pulled the shaft out of the transfer case, about an ounce of fluid flowed out even though I had the rear end jacked up so that the bottoms of the tires were about four inches off the garage floor. Since the garage floor is gently sloped towards the door, I would estimate that the fall from rear to front on the Jimmy's frame would have been about two inches, indicating that the fluid level was slightly above the opening for the shaft. The red fluid also appeared to be quite clean! When I inserted the shaft back into the transfer case I inserted it obviously differently than when I pulled it out because there was no mark showing how it should go in.

So since those are the only changes between the before (noisy) and after (quiet) situations, I wonder if:

1) the noise could have been caused by an imbalance of the shaft the way the Firestone technician had put it back (assuming he took it out, I didn't see him do that), and when I put it back it went back balanced (by chance)?

2) or, if letting out a bit of fluid could have made the difference (not likely, in my view, since so little flowed out)?

I just assumed that he had not pulled the shaft out of the transfer case, but given this experience I now wonder about that. Also would the fluid be so clean if he hadn't replaced it? If he had replaced it, would they not have charged for that? I've thought of going back and asking these questions but I doubt they're remember now.

Any ideas?

 

So all you did was remove the driveshaft and then reinstall it?? Is it possible that you reinstalled it 180* different at the rear axle? If so, then that could explain the "repair".

The fluid loss wouldn't do anything.

 

No, sir, I attached it the same way to the differential - that's where it was marked with chalk. The chalk marks lined up before and they line up now.

 

after speaking with you yesterday about checking both shafts, did you end up removing the front shaft (to inspect the u-joint)?

 

Yes, bud, that's what I was saying - I pulled the front shaft out and inspected the front joint which moved freely and smoothly in all directions - then inserted the spline end back into the transfer case without any marking so I don't know how it went in compared to how it was in there before. Then attached the rear with the four bolts on the differential ensuring that the chalk mark that the Firestone mechanic had put there lined up. Now I have no noise!

It's possible that I rotated the front U-joint 180 degrees (or some other amount since I used no marking at the front) between the time I pulled it out and re-inserted it, but most definitely not the rear one when putting it back.

The important thing is that the noise is now gone, but am very curious to understand how it happened.

 

You may have one of the many mysterys of life. It would not matter if the yoke went into the transfer case in a diferent position than it came out. The good thing is that the noise is gone at least for now.

 

And I thought only computers did weird things!!! Go figure.

 

sorry, a possessed vehicle will put any screwy computer mishaps to shame.

 

Hello guys,

This Jimmy is still running without noises, but I've been experiencing a slight problem lately - don't know if it's tied to the work I did last year, or if it's something that would have happened anyways.

The differential case leaks a little near the bottom by the cover plate. I've twice tightened the sucker as much as I could (the bolts turned very little) without using an extension on the wrench for extra leverage to really tighten those bolts, but don't know if that is a smart idea!

I sure would like to stop that small leak without having to replace the cover plate, gasket and differential fluid. When I did this work last year, the cover plate looked good so I cleaned it really well and reused it, the gasket I replaced, of course.

Any ideas?

quickcurrent

 

If you did not inspect the cover and the differential housing carefully there may be a piece of old gasket material on there or something wrong with one of the mating surfaces. Don't over tighten. All you do is risk distorting the cover or breaking the bolt off. GRRRR
If you do not want to take the cover off use brake cleaner and a brush. Clean the area real well, let dry and apply a bead of silicone gasket sealer between the cover and the housing. If it works great. If not you can either live with the leak or take the cover off again.