JD175 Hydro (1988 model) Hydro transmission problems [Archive] - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information

: JD175 Hydro (1988 model) Hydro transmission problems

08-08-2008, 11:36 AM
I just got a John Deere 175 back that I had bought new in 1990. I sold to a neighbor about seven years ago and he never even started it, just let it sit in the weeds.

After new fuel, sparkplug and oil/filter change the Kaw engine runs great, but the tractor doesn't want to move when I push the hydro lever. It will sometimes move a few inches (either direction) with the throttle full on and will move several feet if engaged while the engine is idling (???). It will also try to move more if I rock the chassis hard from side to side.

The tranny will engage and work like it is supposed to if I push the tractor by hand to get it rolling first, but will quit moving forward if I let it slow down very much.

The drive belt isn't slipping and the mower blades work fine when engaged. The Hydro unit is full of oil.

The guy I got it from might have pushed it around without using the hydro release lever.

Anyone know if this is a serious problem that will require replacing the Hydro unit, or maybe something simple that I might have overlooked? If it does need a new Hydro unit, what model would it be and where would be the best place to find a cheap one?

08-08-2008, 11:54 AM
Are you sure the belt is not slipping?.... all the symptoms indicate a belt problem...

The tranny will engage and work like it is supposed to if I push the tractor by hand to get it rolling first

This tells me the tranny is OK. If he pushed it around without disengaging, he would have stripped gears if anything, and which case you'd know it. Did you change the oil in the tranny?... maybe worth while...

also, check to see if the brake lever is not stuck... and of course check the fwd/rev lever action on the tranny...

08-08-2008, 12:45 PM
The fan on the side of the Hydro unit spins equal to the engine rpm at all times. The belt feels tight and has a decent amount of tension from the tensioning spring/idler pulleys.
The brake isn't stuck or binding. Tractor rolls freely when pushed and the automatic ‘return to neutral when brake is applied’ function works correctly.
Hydro oil isn't supposed to be changed per the owner’s manual and I doubt the previous owner did anything to it since the tractor literally sat in the weeds without being started for the last seven years.

I will check the linkage (and everything else) again. Does the Hydro release rod that sticks out the front of the unit have any kind of adjustment?

08-08-2008, 10:52 PM
Did you change the oil in the tranny?... maybe worth while...I think I found the problem. Even though the hydrostatic fluid level showed to be full, I added a couple ounces of 30-weight motor oil. It seemed to work better so I added some more. I added about 8-ounces total and it seems to be moving almost like it should. The oil level is about 1-1/2 inches above the full screen now which means about 6-onces of oil went somewhere in the hydrostatic housing. This also explains why rocking it side to side would get it to move more than sitting still.

The oil seems to be a little thin.

Now I wonder if I should take the chance of breaking it beyond all repair by changing the hydrostatic oil. Is there anyone on the forum that has actually changed the oil in a 30-weight using hydrostic unit that can give me some advice?

08-11-2008, 06:27 PM
Should I change the hydrostatic transmission oil even though the user's manual says not to? The oil is 20-years old. Will it need any additives?

*It is running perfect now...

08-12-2008, 10:50 AM
I don't see any risk in changing the hydro oil if you can (I assume there's a oil drain plug on the bottom). I use 10W-30 and 30W in my Wheelhorse hydro and have changed it 5-6 times since I bought it. Only issue I have sometimes is that it takes a while for the air to work its way out when I change the oil. It has a small diameter dipstick tube that you have to pour the new oil down and it has trouble burping the air out as the oil goes in.

08-12-2008, 11:39 AM
there is a sticky about changing the oil in a K46 hydro at the top of this forum. though your hydro may be different a similar method would apply. remove it from teh tractor, flip it and drain it out. goto the manufacturer's site and get the specs, then refill it with teh proper amount of recommended oil. reinstall.

you say the oil looks thin, maybe it has a thinner weight oil or maybe it has had water in it. either way, teh best course of action for something so neglected would be to change ALL fluids, plugs, AND belts. even if they look ok, they are likely very degraded.

08-12-2008, 02:03 PM
what davidg said...

08-12-2008, 02:33 PM
what davidg said...

Maine Willy
08-12-2008, 08:34 PM
For what its worth, I bought a 175 new in 1986 ( or 87?) and when I went in for the first service, they told me the Hydro oil did not need to be changed as they had done in previous years. It implied they used to change the hydro oil previously, so it seems to me that changing it is something that has been done before. Why do I remember this after 22 years? because I had a hard time with NOT changing fluids in any equipment.
Regarding what fluid ot use, My suggestion is to ask a JD dealer. When I talked with them about chaning it (even though not required) they said it took a special oil.

08-12-2008, 09:36 PM
Today I asked the local John Deere service tech about changing the hydro oil, but he gave me so many wrong answers that I don't trust anything he said to be correct.

He didn't know the differential was separate from the hydrostatic unit or that it used different oil.
He didn't know the hydro unit didn't have a drain plug.
He didn't know the service manual said to use 30-weight motor oil in the hydro and 90-weight in the differential.
The tech didn't know the hydro unit had a large fill tube or how to check the fluid level in either the hydro or differential.

When asked, he said the hydro unit didn't take any special additive or friction modifier, but he was wrong on so many other items that I doubt he actually knew what he was talking about.

He also said that John Deere put the warning in the owner's manual to “not change the hydro fluid” because they thought the tractor's other parts would be worn out in a couple years; long before the oil would need to be changed in the hydro unit. He said John Deere never expected any of those tractors to be running at five years (his opinion of how long hydro oil is functional), much less twenty years.

His basic premise was the tractor was old and therefore should be discarded because it had lasted longer than what he thought its useful life expectancy was. It didn’t seem to matter to him that it was still working just as well as it did the first time I used it when I bought it twenty years ago.