-86 300GD Transmission removal, bad trust bearing.
never removed the transmission before on a G. got the 711.422 manual 5speed.
could someone give some quick pointers and tips before i dive into this. getting a friend over today, so thought i should use the manpower and take the gearbox down and up while he was here..
Hi
Accessing all the bolts without the correct tools (thin wall socket set with universal extensions) will be a problem as will the shallow headed bolts around the flange to the short propshaft ( thin spanners )
observe the correct position of the control rods linking the gear lever mechanism before removing and make sure the retaining clips are put back as they were removed ( masking tape with A to A B to B code to identify ends)
would be a good idea to examine the pressure plate and friction disc while you are in there ( any blisters or scoring will mean replacement assembly) and be sure to hang the thrust bearing properly on the carrier otherwise it will rattle on the spigot shaft when engine idling
.any sign of oil dripping from behind flywheel or splashed about inside the bellhousing could be failed crankshaft seal or back pressure from worn piston rings pressurising the crankase ( major problem )
service the hydraulic slave cylinder / flush the old hydraulic oil out of the system ( if oil is black you may have some corrosion internally in the master cylinder and slave cylinder if so you need to replace both
check all related pipe work for any degrading
good opportunity to service the diff lock mechanism ( easier access with G box removed )
Not just a case of fitting a new thrust bearing!
Happy New Year
Hi
4 speed G'box !
is there any float or excessive backlash on the spigot shaft which could indicate internal problems with the box
Hi
4 speed G'box !
is there any float or excessive backlash on the spigot shaft which could indicate internal problems with the box
probably a typo 717.422 5 speedGet-rag?
sounds like first motion shaft bearings to me...............
SK
I agree with Steve Kirk's comment, possibly input shaft bearing.
If you are currently using ATF oil in the gearbox, change to using the conventional mineral oil. Being a thicker oil, it may reduce the noise but no guarantees of cure; for that, only bearing renewal will do. Note: although I do not expect it, using thicker oil could give you stiffer gear selection but high mileage of your vehicle should compensate for that.
There are oil additives available with claims to reducing noise; in a few examples of where I have applied these additives my results have been' iffy' at best. In my opinion. these additives are fine when new bearings are installed and use of additives help fortify the standard oil but if noise issues arise at a latter date, it is usually too late. Then, the only remedy is to renew.
If the noisey bearing is bearable, live with it, it is unlikely to cause a mechanical issue unless the noise deteriorates drastically.
As some on our forum might say, turn the Radio on louder. 
As some on our forum might say, turn the Radio on louder.
LOL works for me.
Spider1V
i dont even got a radio yet! :D
but some oil came out when i steamed the tranny, and it is not ATF oil on it now. will try to change the oil before doing anything drastic though..
what kind of boxes would be a direct swap from other mercs? how much work to put in a auto trans?
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thank you so much for such a comprehensive answer.. the box came down alright.. checked the trust bearing, it was all good. but the dust cover for the pilot bearing was loose. hoped that was the source for the noice.. but no such luck.
i got a low rpm noise from the gearbox when idling, but when rpm are over 900 or clutch is engaged it is gone.. anyone got any ideas? input bearing perhaps?
will probably source out another gearbox if it is not a easy fix.. mine is a 711.422.