Sorry cat lovers but my neighbor asked a question I could not answer,he has a 350b (1971) with power shift.The machine starts right away and after warm up it runs great for 10 minutes then becomes sluggish on forward,reverse and also turning.I did notice that the main hydraulic return box sight glass showed the oil as milky in color,would that explain the problems ?
Also aside from draining the hydraulic oil from the main box are there other points to get all the fluid out for a new change ?
He is a great neighbor so I will risk my deer questions in front of a pack of wild cats This is one place I have never been let down due to the immense amount of knowledge.Thankyou

John in the caribou (bc)~~~~~~~~~~~

I don,t know a thing about a JD but the milky oil sounds like it has some water in it for some reason.

Hi John,
don't know about JD's either, but, may be the oil return baffle is broken off inside the hyd. tank or a hose or line connecting the baffle has split. I had this on a 988 once with overheating and poor hyd. performance. Found the baffle hose had moved and return oil was spraying about and aerating inside the hyd. tank.
Or it could be water as suggested by SJ. If the oil is milky after sitting overnight I would suspect water but if it is normal oil looking and goes milky after the 10 mins. running mentioned then something is aerating the oil.
Hope this helps,
Cheers,
Eddie B.

All my experience with JD powershifts is farm tractors, not dozers, but your symptoms sound like one of a couple of things. A worn transmission pump that can't build pressure/flow with normal, hot oil, or possibly a high pressure hydraulic oil leak back to the sump that is aerating and/or rapidly heating the oil above normal temperatures so it's too thin (and also is wasting pump capacity). Oil temperature rise may key you into which is the most likely, and sometimes you can hear a high pressure leak if you listen at the transmission filler opening.

It would be a good thing to drain the transmission and change filters. Some have a couple of drain plugs to get all the oil out, so check for 'em. While you're there, there is usually a transmission pump inlet screen in the very bottom of the transmission behind a plug that can be removed to pull the tubular screen out for cleaning and inspection. The pump inlet screen plug is usually in the side of the bottom of the transmission so the screen lays along the bottom of the case. Frequently is a 1/2" female square in the center of about a 1 1/2"--2" plug. Can be really tight since everyone seems to make sure they won't come out;)

I don't know if the dozers have wet steering clutches/brakes, but when you find a lot of black crud in the filters and brass slivers in the pump inlet screen of a tractor, the brake disks are usually going bad on one side or the other. Of course with a dozer, it could be clutches too, but don't have any experience with that. The transmission clutch packs don't seem to just go to pieces like that, but maybe I just haven't seen one here.

Long term, it doesn't do the transmission pump a lot of good to be pumping this debris into the filter, so frequent filter changes are a temporary stop gap only and potentially could cost another tractor split to R and R the transmission pump instead of just the brakes.

Going through this now with a 4440 tractor.

To loosen the round plug with the 1/2 square in it, to gain access to the screen, hit it hard a few times with a hammer, and it should loosen right up.
Most people don't even know that this screen is there, if I remember correctly some of the large frame tractors, and 4WD's, have 2 screens.
What we would sometimes do, and I did to my 4020, was to put a couple of 'cow magnets' inside this screen to prevent metal from getting further into the system.
Over the years vibration would wear a hole in or crack the suction tube to the charge pump, causing it to loose prime.
Again, this was on ag tractors, and may not have been used on industrial units.

Speaking of Jd 350's, I have heard that the rollers from these machines will fit on D2's. Anybody know anything about this? I believe I saw this statement posted on this site or the ACME site about 2-3 years ago.

Just adding my experience with a 550A (1975) dozer. It had the problem of being very sluggish forward and back and turning slow; then not moving at all when warm. I took the engine, torque, and transmission out which is alot of work on a JD. After taking everything apart and replacing a few bearings and updating seals, I found the transmission pump pick-up screen completely plugged with what appeared to be brake lining material. I had to take the screen apart to clean it, then re silver solder it back together. At this point I bought a used service manual, also realized just how costly jd parts are. This was a difficult job, and I recut the trans shafts to double up on the fiber seals, due to wear from the old steel rings. The pump can be removed from underneath on this model, with puller bolts and requires lock-tite around the inlet and outlet ports when sliding it back into the case. I sold the machine after this and never did disassemble the steering clutches hoping to find the cause. Phil

If you haven't solved your problem I have A teck. manual For a 450 B
Which was ALMOST the same. if need be I will scan or mail you copy's of the pages pertaining to trans-

let me know

The early 550 used a "Twin Disc" transmission That probably should not of ever been released with all the problems these models had.
A 350 -450 had a very different setup that gave little trouble,as best I remember.

A JD350 dosnt have a powershift like the 1010,2010 or 450 it uses a Hyd. reverser just a small unit ahead of the reg trans. and your probably getting the water in around the gearshift boot the foot pedal is is not a cluch its an inching pedal that controls fluid flow be sure its not hung up if is is the reverser will got bad fast, the inching pedal should only be used when make a fast stop otherwise keep feet off

Lots of experience with hydraulic reverser arrangements (in farm tractors again:D

Does the 350 have a torque converter arrangement along with the reverser?
I believe the one in our 310 backhoe is a Borg Warner unit. It has electric forward/reverse solenoids instead of a manual linkage. The utility tractors had a reverser arrangement without a torque converter.

The linkage on the pedal would be a good start as Willie says, There cannot be much wear there or the control valve will not apply pressure to the clutch packs properly. We had one that commonly broke a roll pin which we kept wired in the pedal to valve shaft, so it couldn't fall out. With just a little more slack in the joint it would stop engaging the reverser packs.

There may be an adjustment screw for the speed of clutch engagement that can be opened up a little to make it more positive, but crud/water in the oil was usually the root problem there and after an oil and filter change, the pressure would be back up where it was supposed to be and the engagement needed to be slowed back down again.