2000 JD 990 4wdr problem

[wr400]

I was pulling a 9ft drag with my 990 in 4 wheel drive an noticed some noise from the front end. Four wheel drive stopped working now. This tracter has 175 hours on it. Never been on pavement an is clean. I dropped the oil in the front end only to find it is clean with no metal shavings. Pulled the drive shaft an no broken coupler. In 4wheel drive the front just chatters now.
How bad can this get? I was pulling on some slick clay when it happened.

 

[mfreund]

Sounds like there is a problem in the differential. Here is a exploded parts diagram

John Deere - Parts Catalog

 

[kebo]

When you pulled the driveshaft to the front axle, did you have the front end jacked up? If so, I assume you tried turning the input shaft by hand. If you tried that, what happened? Both tires rotate? Just one tire rotate? Neither tire rotate?

 

[AKfish]

I was pulling a 9ft drag with my 990 in 4 wheel drive an noticed some noise from the front end. Four wheel drive stopped working now. This tracter has 175 hours on it. Never been on pavement an is clean. I dropped the oil in the front end only to find it is clean with no metal shavings. Pulled the drive shaft an no broken coupler. In 4wheel drive the front just chatters now.
How bad can this get? I was pulling on some slick clay when it happened.

The problem might not be in the "pumpkin" or differential. You might have a broken axle or a problem with the planetary gears in the wheel assembly.

Good suggestion from kebo - jack it up and with the axles supported - spin the driveline and each wheel. Both with 4x4 engaged and not. Listen and feel for grinding, clunking, etc... that can help to isolate where things have gone wrong.

Keep us in the loop.. good luck.

AKfish

 

[wr400]

with the front jacked up both wheels turn! No noise but they do turn oppisit of each other.
Jeff

 

[kebo]

with the front jacked up both wheels turn! No noise but they do turn oppisit of each other.
Jeff

So it would seem that the front axles and differential are ok. The two tires will rotate in opposite directions due to the open differential.

I would jack up all four tires, put it in 4x4 and in low gear. Crank it up, ease the clutch out, and see what happens and if you still hear the same sound. IF the front wheels don't turn then, something maybe damaged or broken in the transmission where the front driveshaft gets its power from. IF all that works, then see if you can listen where the sound is/was coming from.

 

[wr400]

Jacked the tractor up No strange noise coming from any where! Went to dump the front diff oil an it was under pressure! How or why? Came out nice an clean but what is causing pressure an could that have been the problem. I looked all over for a vent but couldnt seem to find one. Any ideas?
Jeff

 

[wr400]

Jacked the tractor up No strange noise coming from any where! Went to dump the front diff oil an it was under pressure! How or why? Came out nice an clean but what is causing pressure an could that have been the problem. I looked all over for a vent but couldnt seem to find one. Any ideas?
Jeff

No body has any Idea to why the front end is building up pressure? Or if there should be a vent to relese it?

 

[irwin]

No body has any Idea to why the front end is building up pressure? Or if there should be a vent to relese it?

That's a good question. Do you have the service manual? If the manual doesn't answer you could try contacting Deere via their main site. Some questions haven't been asked yet here.

I had a 770, yes it's smaller but it's very similar. I don't remember any vent on the front pumkin..but that doesn't mean there wasn't.

 

[wr400]

Ok here is a update! Finally got to dig into it. the plate the holds the axel in the tractor was loose cant see it couldnt tell the bolts were loose but sure enough they were an that is what was causing the problem with the MFWD.

Guess the axel would pull a bit an cause the drive shaft to slip.
Any way all is good.