NV3550 Problems - Grinding noises while coasting

[Dukes69]

Hey Folks, maye you can shed some light on this subject.

2002 TJ 44,000 miles
4.0
NV3550 Tranny

A couple months, before a Moab trip, the tranny started to make some grinding noises, usually in 4th or 5th, while coasting (clutch in) at about 45-50 MPH. I could take it out of gear and put it in different gears(with the clutch still in) and the noise would still be there. There is no grinding noises while accelerating. But there is a slight noise when I apply a SMALL ammount of pedel.

I changed the Diff's fluid, noise remained. Changed the t-case fluid, noise remained. Changed the Tranny fluid, noise went away.

COOL!!


Fast forward to now and the noise is back, same as before. Tranny fluid has maybe 3-5k ok it, as do all the other fluids.

The Fluid that is in there now is the Penzoil syncromesh stuff. I was thinking about going to the dealer ship and buying their stuff, but wanted to as everyones opinion first.

What do you think?

Thank you
Chris

[blkTJ]

What do you think?

something's broke.

hehe, sorry, couldn't resist. :yay:

[Dukes69]

something's broke.

hehe, sorry, couldn't resist. :yay:

Thanks Brian . . . Tremendous help as always!!

[JeepJunkie]

mine sorta makes a whirring noise when i coast clutch in, sounds like rattling berings sorta...

just a guess but is the clutch fully engaging or disengaging?

[nagal]

This sounds very familiar but for the life of me can not figured out from what.

I'll search around and see if I can find out where I heard this before.

[blkTJ]

Thanks Brian . . . Tremendous help as always!!

no prob. I try to help out whenever possible.

[Bachman]

I think they all do that...when mine was new I took it into the dealership and they replaced the tranny and it made the noise too???. Now days I don't even hear it anymore. You could always just turn up the radio!

[NAILER341]

take the damn thing back! it is still under warranty. let them figure it out!
CHRIST!

[Dukes69]

take the damn thing back! it is still under warranty. let them figure it out!
CHRIST!

Yeah, I guess. I just dont want to have to pay the $80 diagnostic fee just to have them tell me that they wont warranty it becuase its modified. I guess its worth a shot. The noise went away when I changed the fluid to the Mopar stuff, but it has now come back. It is less noticeable, however, since we got rid of the full doors.

[NAILER341]

i'll bet it is synchronizers taking a crap.

[Dukes69]

i'll bet it is synchronizers taking a crap.

It shifts like a dream. I'm pretty sure the syncros are fine. Sounds like a bearing or gear mis meshing problem.

[rick]

The gears don't actually change "mesh", they are always riding against the same gears regardless of which gear you are in (well, except for reverse) - only the synchro teeth hold it "in gear" by mating the shaft that the synchro ring is connected to against the gear that you are shifting into. See here for a more coherent explanation:

5 speed trans - how stuff works

This thing helped me understand why my trans was making worse noise in 5th than in any other gear - 5th is out on the end of the counter shaft which means the rear bearing (which was shot) had much more load on it in 5th. I'm guessing this is a possibility for your 3550 also, just that it obviously is not so bad to make noise all the time. I'm curious why this only happens with the clutch in, but I'm thinking maybe if the bearing were just a little loose that it might chatter with the clutch in but not necessarily make noise under load?... I think if the synchros were going it would pop out of gear because the little dogs that hold the synchro ring against the gear start to get rounded off and lose grip. Does it ever pop out of gear?

[Dukes69]

Does it ever pop out of gear?

no, no poping out of gear or shifting problems. I would hope a 45k mile NV3550 wouldnt be fugged up . . . but I guess its possible.

[Bachman]

Chris, let us/me know what the news is on that tranny. Mine seems to be doing the same thing. After the t-case went out the tranny started making noise. I would like to have some idea what this is going to cost...

[Dukes69]

Chris, let us/me know what the news is on that tranny. Mine seems to be doing the same thing. After the t-case went out the tranny started making noise. I would like to have some idea what this is going to cost...

I just saw that you posted the same problem. I have NO clue WTF this is. It seems to go away with a fluid change, but comes back in a week or 2. Maybe I'll bite the nut and take it to the dealership and see what they say.