Yanmar 1500

torahbeliever · Dec 21, 2011

I have a 1979 Yanmar 1500 purchased with no manuals or instructions. Beneath the seat there is a valve with a handle resembling a water spigot handle. Fluid is leaking from the stem of this valve and I need to know it's purpose and where to find repair information!
Thanks for your help! :confused2:

Scotty Dive · Dec 21, 2011

Definetly get a manual from Hoye or another site. Here is a link to the schematic:

Yanmar Tractor Parts: HYDRAULIC_LIFT

torahbeliever · Dec 21, 2011

Thanks!!!

Scotty Dive · Dec 21, 2011

Check the Yanmar section of TBN. There are a lot of folks who have your tractor. There a few VERY good and relaible parts dealers sprinkled across the US too!

Mechanos · Dec 21, 2011

From what you are describing... the valve you are referring to is the Rate-of-Drop" valve for the 3pt hitch. I have a JD 955 (a close cousin to the Yanmar, as I understand it) and I have this same leak. I have tried replaceing the gasket and o-ring in the nut that the stem protrudes through with no luck. Just yesterday, I ordered the internal o-rings for the valve itself. It's a relatively simple procedure to replace this o-rings... remove the the stem housing, remove the valve, replace the o-rings, put it back together. I'm hoping this will take care of my leak.

As it is now, fluid only leaks from the stem when I have an implement on the 3pt and it is in the raised position. When I lower the implement to the ground and remove pressure from the rockshaft piston, the leak stops.

torahbeliever · Dec 21, 2011

This describes exactly what I'm faced with. Thank you so much for your response and schematic.

Mechanos · Dec 30, 2011

Just following up... I finally got around to replacing the o-ring on my ROD valve and that took care of the leak. It is a very simple procedure... once you get down to the valve. I don't know about your Yanmar, but I had to remove the rear fender, the seat and the seat mounting bracket to gain access to the valve. The valve slid right out of it's bore with no resistance. With the new o-ring in place there was noticable resistance when the valve was reinstalled in it's bore.