'70s D series, doesn't move, no hydraulics

[10berryd 0]

I recently bought a 18 hp automatic Wheel Horse. The seller said last fall it seemed a little slower so he changed the hydro oil and filter (Fram PH16.) This spring it would not move when he started it. He thought the pump was bad. 

 

When I got it home I had it parked on a slight hill while I was looking it over. I tightened the push valve to keep it from rolling. I noticed it crept very slowly. The next time I started it, I got some buzzing from the hydro motor and it even drove about 30 feet. 

 

I am now back to no response from anything hydraulic, including deck and 3 pt lift.

 

Anybody have any suggestions where I should start?

Dan

[pfrederi 18,382]

What does the fluid look like and smell like?  If teh fluid looks decent i would start with a new filter.  Frams are not noted for high quality and I am not sure PH16 is the right one. 

 

WH 102819 or Wix 51521.

 

Does teh coupler between the engine and teh pump look OK?

 

Still have a problem need to do a charge pump pressure test.  Do you have /access to a hydraulic pressure guage???

[10berryd 0]

Fluid looks fine. I bought some ATF and a Napa Gold 1410 filter. Tomorrow I'm going to pull pump and look at charge pump. I wasn't getting any pressure from the charge pump.

 

The coupler between the engine and the pump looks good.

 

Dan

[JamesBe1 82]

Dan,

It sounds like you are on the right track.  There are some threads/pics/videos around here to help you rebuild your pump.  You might get lucky and pick up a good used one, but they are getting harder to find.

 

BTW, you mentioned ATF.  The hydro systems usually run motor oil, but some people have been known to swap over to ATF.  You might want to doublecheck what you have in the system before you add the ATF.

 

If you don't already have it, this should help:

[10berryd 0]

Well when I pulled the drain plug on the hydro, the fluid slowly dripped out. Also, I found a leak in the hydraulic manifold that would cause it to drawn in air while going forward and leak fluid in reverse.

 

The piston pump and charge pump looked pretty good, Not perfect but not worn out either.

 

Is it possible to weld on the manifold? I was thinking about putting a small tack right on the pin hole. It appears to be leaking right where the line goes into the manifold pad at the rear of the tractor.

[JamesBe1 82]

Dan,

 

Did you remove the dipstick before you removed the drain plug?  Air needs to get into the system or it will drain slowly.  That might account for the fluid slowly dripping out.

 

Yes, I think the leak you found is probably the source of your problems.  I don't think you will hurt anything by tacking it with a welder.  In fact, you can see that the manifold lines are welded to the manifold pad (at least that is what I remember seeing).

 

I'm kinda curious as to what caused the leak.  Internal corrosion?  Vibration?  Either way, if you seal it, you'll probably be good to go.

 

If, by chance, you should hurt the manifold, I find that they often come up on ebay.

[10berryd 0]

Yes I removed the dip stick. The fluid was just that thick. Thanks for the help, I'll try welding it.

Dan

[Hodge71 665]

Dan The fluid should never ever be that thick. If its not ATF it should be 10W-30 oil. I have a bad feeling someone filled it with gear lube or maybe 20W-50 for some reason. I have heard of people doing that to hide problems with the hydro system. As these sytems age the tolerances get worse and the pump and motor heat up causing the tractor to slow...creating more heat and compounding the problem until they just dont move anymore. The extremely thick oil gets some more life from a shot system. Usually enough for the owner to sell it. Most people cant get the system hot enough with a test drive to get the system to act up but when they get home and use it.....BAM....it too late then.....        

Edited June 4, 2013 by hodge71

[wheeledhorseman 579]

As Jeff says, using thick gear oil is the redneck fix for a hydro that's slowing up or getting weak when hot but if a hydro doesn't perform properly with the recommende oil then something is wrong.

 

It could be that you've found the issue and that PO tried the thick oil trick to no avail and sold the tractor - at least he mentioned the slowing up bit. Maybe he bought the tractor like it and it worked well for a while but something puzzles me though in your description.

 

There are four manifold pipes, two are used by the charge pump, one for it to draw oil from the reservoir in the transaxle, the other to return excess oil from this pump which is 'wasted' back to the reservoir via the implement valves then back through a manifold pipe. The direction of flow is the same which ever direction the tractor is moving in and even when standing still with the engine running. An air leak on the induction pipe could / would cause air to be drawn into the charge circuit.

 

The other two pipes link the the hydro pump at the front to the hydro motor at the rear. Fluid flowing in these two does change direction for forward and reverse and theres no flow in neutral. If there was a leak on either of these then I'd expect oil to leak all the time, perhaps more in one direction than the other but as the hydro circuit is a sealed system and runs even in neutral at the charge pump pressure then it would be, I think a constant leak. 

 

I'm sure one of the others will chip in if I'm wrong on this.

 

Good luck. A number of us have done battle with these things.

 

Andy

[meadowfield 2,662]

To add to Andys post, if its been drawing in air to the charge pump or variable displacement pump, then i'd be very wary of either being damaged due to cavitation.... This usually shows up by seized pistons or grooves on the plates. Adding a thick oil helps with the leaks/ low pressure, but the increased viscosity leads to more chance of cavitation.

Good luck!

Mark

[pfrederi 18,382]

If you try to tack weld the manifold in place you will probably cook the o ring seals. I would disconnect the manifold from the hydro motor and drop the motor before I tried welding.