Drobertson

I haven't seen this problem on your posts. I was loading fencing material on my 2001 Dodge diesel it has a 4500 6speed manual transmission. I had it idling in neutral when I noticed it moving forward just a little....then more.then it moved 3ft ! I got in and pushed the cluch and it stopped. Drove home and noticed it didn't want to go back to neutral felt like it was in maybe 3rd worked it a little and it dropped in neutral again. This truck tried to go into gear while idling.

SIXSLUG

Sounds like you need some clutch work....No 4500 6 speed. You have an NV5600....

KATOOM

The truck was rolling while idling in neutral? There are many reasons why thats impossible...

Fordzilla

I didn't want to be the one to say it......Ben

Drobertson

Yes the truck was sitting still and idling in neutral ! It had been idling for about 10min. Then it kinda sounded like it was lugging down. Then it moved just a little..... then it moved a lot. I engaged the cluch and it stopped. There is no noise in the transntransm/cluch. When I drove it home and parked it it didn't want to go back to neutral it was stuck in one of the higher gears I worked it a little and dropped back to neutral .Coul Couldn't believe it myself

KATOOM

Burn it...!!!!

nothingbutdarts

Why don't you pull the drain plug on the transmission and look for signs of metal/brass, before you do that though, see what the oil level is in it!

AlpineRAM

I think he's gonna find a broken syncro that jams itself ... rare stuff, but I have seen trannys where that has happened. On other trannys with a split input-output shaft the bearing between them can also gall and do that for you.

Drobertson

iii

Drobertson

I bought this truck last September and only use it occasionally. Checked everything but the transmission. My mistake. Take the time to check all the fluid levels."Truck seems to be trying to move while in neutral..... CHECK YOUR OIL LEVEL". Your transmission is crashing!!!

AlpineRAM

Makes a bit of sense, bearings between gear and shaft galling up.
Sorry, but it sounds like rebuild-time for your tranny.
Even if it works so-so with added oil this is only a temporary fix.
All the forward gears except the one that is selected at the moment need to rotate around the shaft, the rpm of this rotation is quite high.
(EG in 6th the 1st gear spins at the same speed as it would if you drove the same speed in 1st... and you do not want to drive in 6th and have 1st gall up completely, a lot of stuff will break.)

KATOOM

It makes no sense that bad bearings would cause anything like this to happen... The input shaft would have to be physically connected to the counter shaft for any power transfer to make it from the engine to the driveshaft.

AlpineRAM

This is a constant mesh syncro gearbox- all the gears mesh all the time, power transfer to the shaft is enabled or disabled by the sleeve that slips onto the counterpart on the gear- the syncro is just helping to harmonize the shaft speeds.


If now let's say bearing #22 seizes to the shaft it is the same as if the power was transmitted from gear 21 to sleeve 97 and the center 98 then to the shaft. Everything dandy until you want a different gear, then you have 2 gear pairings applying torque on the same shaft- and block each other.
And as you also see in the schematic, the input gear #16 is co-axial to the main shaft #2, and they have a bearing between them. Sleeve #90 can connect input to main shaft for direct gear, so galling bearing #91 would put you into direct gear.

KATOOM

I gotta think about this but yeah I see your point...

AlpineRAM

The reason for the big bearing on top of the shaft looking as good as it does was the needle bearing in the topmost gear seizing due to lack of lubrication. As you can see there is coked oil on these parts, they got really hot, and the roller bearing expanded and got more preload until it crashed the cage..
Some parts and creative work later...


At the start of the problem it was just like the original poster described- idling in neutral, engine lugging down, vehicle trying to move. - OK there was a lot of noise from that tranny too, but it took less than 20 miles to go from a little lurch and a little noise to the state of the first picture.. In the top picture you see a broken disk on top of the shaft - the bearing spun so hard that it tightened the bolt holding it to the shaft got tighter until it crushed the disk..