Yanmar 186 lost all hydraulics and tranny power

tysmobiletractor · Jul 27, 2017

All hydraulics and tranny not working.
What do they both share in common?
New fluid. And there is pressure from a leak, so it seems pump is ok?
What can anyone suggest to check?

winston1 · Jul 27, 2017

I know the hydraulic suction screen is up high on the 186. Not sure the power shift pump pulls through it or not. Definitely something to check if you haven't. It is up high on the transmission case left side (sitting in seat) behind a 4 bolt flange. On the right hand side there will be a 3 bolt flange. o-ring seals the left, gasket seals the right.

rScotty · Aug 6, 2017

tysmobiletractor said:
All hydraulics and tranny not working.
What do they both share in common?
New fluid. And there is pressure from a leak, so it seems pump is ok?
What can anyone suggest to check?

Both the main hydraulics and the tranny share the same fluid and filtration, but have separate pumps. The hydraulic pump for the power shift is only medium pressure and is located internal to the transmission. It powers the the power shift clutches and provides pressure lubrication to the transmission shafts. You cannot access that pump externally, but you can measure the pressure from externally with simple gauges at the test ports.

The main hydraulic pump is a high pressure gear pump - and uses the same oil and filters as the transmission. This main pump is located on the right side of the engine just forward of the paper spin-on cartridge type hydraulic filter - which you should definitely replace every few years or so. Normally that main pump only runs the three point hitch lift, although there was an "extra ports kit" available for powering the optional power steering kit and a loader. Pressure from that pump can be checked via a 1" port under the seat. Expect about 2000 psi, so be careful. That pump also has a relief valve which I think is back in the transmission case and it is possible that the relief valve is stuck. But even if it were, the power shift should work normally.

I'd check first that the fluid level is proper, remove and clean the cleanable wire filter that Winston mentioned, replace the spin-on filter...and if things still don't work right it is time to check the pressures in both pumping systems. Then look at the high pressure relief valve.
These systems are all pretty durable; chances are that you can fix it with basic maintenance.
luck,
rScotty

tysmobiletractor · Aug 6, 2017

Great post. Very helpful. Thanks.
I'll be looking into it soon.

winston1 · Aug 6, 2017

rScotty, when are we going to see some pictures of the 165D your restoring?

rScotty · Aug 7, 2017

winston1 said:
rScotty, when are we going to see some pictures of the 165D your restoring?

Thanks for the reminder. I do need to put some pictures together and probably begin a notebook as well. It as the one we bought new many years ago and was immaculate. I had loaned it out to friends when a flood swept through our valley and the tractor was found downstream. Lots of flood repairs here have slowed the restoration, but I did get some of the electrics done this summer. Engine doesn't turn, but that might be in the clutch housing. Transmission seems OK....
rScotty