JD 7800 Powerquad: metal parts in transmission oil

   / JD 7800 Powerquad: metal parts in transmission oil #1  

yamahahonda

New member
Joined
Sep 5, 2019
Messages
4
Tractor
John Deere 7800
Hi,


It seems that, unfortunately, our JD 7800 will need to have the differential and/or gearbox repaired. We were in the middle of changing the hydraulic-transmission oil and everything was going well until we removed the oil line on the front left side of the differential case. As seen in this picture:
We found metal parts in the oil - smaller pieces have come out together with the drained oil, while "T" looking part and few others were kinda stuck near the drain hole, so we were able to reach them and remove them with a magnet:
We bough this tractor around 3 years ago and we changed the oil and filters at that time. The tractor haven't even reached the 1500 hours yet (as written in the manual for the transmission oil change) but we decided to change it this year, since we are servicing the tractor and changing other fluids anyway.

We had some strange problems with transmission oil pressure in 2019 but changing the transmission oil pressure sensor appeared to have fixed them. Other than that, the tractor seemed to be working fine, all the gears, differential, PTO worked, we did not notice any weird noises or transmission behavior. The previous owner also told us that he did not have any problems with it. The hourmeter on the instrumental panel shows ~11,000 hours.

Anyway, the local John Deere dealer won't be able to come until the next week. Maybe someone have seen something similar and knows what part could have broken? The "T" metal part is somewhere around 4 cm in length. All the bits are hard and do not bend at all.

I've checked through the whole John Deere Parts Catalog for 7800 Powerquad with MFWD online and I did not manage to find anything that could resemble these metal parts.
 
   / JD 7800 Powerquad: metal parts in transmission oil #2  
Size of part may be deceiving but my guess is part in photo is a piece of roller brg cage that was designed to keep rollers separated on a tapered roller brg. Trans/diff contains several tapered roller brgs.
 
   / JD 7800 Powerquad: metal parts in transmission oil
  • Thread Starter
#3  
Thanks for the reply, Tx Jim.

Yeah, I can now clearly see that it is a bearing cone, I don't understand how I managed to overlook it while looking through the parts catalog.

Looks like this will be a big and expensive job, and, unfortunately, I doubt that me and my mate will have enough time and skill to do it ourselves.
 
   / JD 7800 Powerquad: metal parts in transmission oil #4  
I think TxJim Nailed it!
I would have the Parts guy bring out the bearing used in the differential and rear axle to compare. There are only 2 bearing cones for each.
You may have caught it before any real $$$ damage.
If I had to guess, it would be left axle inner cone bearing P/N JD8951
 
   / JD 7800 Powerquad: metal parts in transmission oil
  • Thread Starter
#5  
So, an update. Our 7800 has been at the JD dealer since last week, and I'm relieved to say that these metal parts were leftovers from a previous failure/repair. It seems that it was the differential that needed to be repaired sometime in the past, and whoever did it, somehow forgot to do a proper cleanup.

All the parts in rear axle and differential are in good condition. We did not have any major problems with transmission, but since the whole rear end of the tractor is disassembled anyway, we might as well have it thoroughly checked and replace some parts if needed. We also plan to change the brake discs, while we're at it.

Thanks guys for taking your time to reply to this thread.
 
 
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