yanmar 186d trans

[jerrybob]

Bought a yanmar 186d earlier this week and played with it today. Seems to have a problem with the transmission. When I put it in reverse to back out of shop.....it didn't seem to engage for serveral seconds.....then it slipped into gear. Same problem when I tried the forward gears. After it engaged....I drove it to a neighbor to do some minor work on tractor. When I tried backing out of his shop......same problem. When I went to move forward....we couldn't get it to engage at all. After trying almost every gear.....we finally got it to engage in low range/low gear. I spoke to a local yanmar tractor guy......he thinks it has the wrong fluid in trans. He recommends draining, cleaning screen and replacing fluid with JD 303. He said if I cannot get 303.....to use Dextron 3. He believes my problem will be solved with the fluid change. Any other thoughts out there? I am new to tractors so any input would be helpful. Thanks

 

[California]

When I went to demo my YM186D it seemed slow to start off in any gear. But it engaged solidly within a reasonable time so I bought it.

After replacing the fluid and filter, it engages faster, but not quite as fast as the A/T in a car when you shift from Neutral to Drive. Yes JD303 is what Yanmar recommended 'back in the day'. Later tractor fluids include JD303 among several standards they meet. I use the inexpensive version from Autozone and I see TractorSupply gets theirs from the same source. Some here have suggested that automotive A/T fluid is better for cold climates.

Having some delay in the transmission is an intentional design 'feature'. After you let the clutch out, that starts a little hydraulic pump on the input shaft of the transmission and this fluid pressure then engages the little clutches inside the transmission, which starts the wheels moving. (The pump in the transmission is unrelated to the other hydraulic pump that powers the 3-point).

Similarly, shifting from neutral to L or R sends fluid to the internal clutches, but through a restriction orifice that moderates how fast the little clutches engage.

I suspect this designed-in delay is so the engine can start the inertia of a big tiller instantly as the clutch is is let out (direct mechanical connection), a moment before the fluid pressure builds up to engage the transmission's internal clutches to get the wheels moving. This is a very clever solution to a design challenge. On my older YM240, the torque needed to get a rotary mower spinning is applied simultaneous to starting the tractor in motion. I think this delay in the Powershift allows the equivalent of starting off in a higher (ground speed) gear. Or in practical terms, permits a smaller engine to do the work of a larger one.

Below is Hoyetractor's picture of the Powershift clutches. (1 and 2 in the diagram below). Half the clutch plates are splined to the central shaft, half to the outer shell. Applying hydraulic pressure to a piston next to the clutch plates pushes the drive and driven plates into engagement.

An automotive A/T is similar but has an additional component for smooth starts: the torque converter or 'slushbox', that has one fan driving another fan which is not quite a solid mechanical link. Yanmar's Powershift has no torque converter so there is a direct mechanical link all the way through the transmission after the clutches are engaged.

Very clever, Yanmar!

 

[1danny]

Bought a yanmar 186d earlier this week and played with it today. Seems to have a problem with the transmission. When I put it in reverse to back out of shop.....it didn't seem to engage for serveral seconds.....then it slipped into gear. Same problem when I tried the forward gears. After it engaged....I drove it to a neighbor to do some minor work on tractor. When I tried backing out of his shop......same problem. When I went to move forward....we couldn't get it to engage at all. After trying almost every gear.....we finally got it to engage in low range/low gear. I spoke to a local yanmar tractor guy......he thinks it has the wrong fluid in trans. He recommends draining, cleaning screen and replacing fluid with JD 303. He said if I cannot get 303.....to use Dextron 3. He believes my problem will be solved with the fluid change. Any other thoughts out there? I am new to tractors so any input would be helpful. Thanks

I would also replace the hydraulic filter, with an OEM filter.

Danny

 

[jerrybob]

Thanks guys......good info. Going to work on it today. Would I be able to buy a hydrolic filter at a local auto parts store?? Do you think they could match a filter??

 

[jerrybob]

Problem fixed.....thank goodness. The fluid was in terrible condition......milky....maybe had water in it. The screen was really a mess....lots of junk. Changed fluid with dextron 3, cleaned screen and changed hydrolic filter. Here's what what really interesting..............after completing work.....we started tractor and tried the gears. Nothing worked......very disappointed. We realized we didn't put the fill hole cap back on....my buddy said that wouldn't cause problem. Put cap back on.....trans works fine. All shifting worked great. 3 point works great. We couldn't believe it! Just to test our theory.....we took cap back off. Trans. wouldn't engage in any gear. Put cap back on......everything works great. Lesson to be learned here......cap must create pressure in system. In any event.....all works well now. I plan to run the tractor for a few hours......then change filter, clean screen and replace fluid with JD 303. Thanks to anyone who provided advice.....this is a great forum for tractor info.

 

[normde2001]

The Hy/Tran system is not supposed to be under pressure at that point.

 

[jerrybob]

That's what I would think as well........but what I mentioned is what happened. Cap on.....all is well. Cap off.....won't engage. Right now....the trans seems to be working great. Drove tractor home.....about 1/3 mile.....shifted into various gears.....all are working. Go figure.

 

[triker01]

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Problem fixed.....thank goodness. The fluid was in terrible condition......milky....maybe had water in it. The screen was really a mess....lots of junk. Changed fluid with dextron 3, cleaned screen and changed hydrolic filter. Here's what what really interesting..............after completing work.....we started tractor and tried the gears. Nothing worked......very disappointed. We realized we didn't put the fill hole cap back on....my buddy said that wouldn't cause problem. Put cap back on.....trans works fine. All shifting worked great. 3 point works great. We couldn't believe it! Just to test our theory.....we took cap back off. Trans. wouldn't engage in any gear. Put cap back on......everything works great. Lesson to be learned here......cap must create pressure in system. In any event.....all works well now. I plan to run the tractor for a few hours......then change filter, clean screen and replace fluid with JD 303. Thanks to anyone who provided advice.....this is a great forum for tractor info.

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hi jerrybob!



the cap you wrote about is it the yellow one on the rear end of the tractor?
you wrote about something called screen??


i found a stick behind the right fronttire do you know what that is for? trans or the hydr.

i found having problems with my sweeper to lift and sink or tilt it.... takes time....


thnx in advance!!

ps: god my gramar sux..... i used to be A-student in ENG overhere :confused2:

 

[jerrybob]

Yes....the yellow cap under the seat in rear was what I was talking about. Since my post......I have found out it just took a little while for the fluid to circulate.....pressure was not the problem. The stick you found on the right front axle behind the wheel is for 90 wt. gear oil.......lubricates your entire front end. As for trans/hyd fluid......look on the left side under the seat....should be a dip stick there for these fluids. Fluid should be JD 303.....dextron 3 also works well. The screen referred to is also on the left side near where your left foot would be if you were sitting on your tractor. The screen is behind a plate with three bolts. There is a cleanable screen behind the plate.....mine had some gunk in it. Hope this helps.......I really enjoy my 186d....hope you enjoy yours as well.:thumbsup::thumbsup:

 

[triker01]

Yes....the yellow cap under the seat in rear was what I was talking about. Since my post......I have found out it just took a little while for the fluid to circulate.....pressure was not the problem. The stick you found on the right front axle behind the wheel is for 90 wt. gear oil.......lubricates your entire front end. As for trans/hyd fluid......look on the left side under the seat....should be a dip stick there for these fluids. Fluid should be JD 303.....dextron 3 also works well. The screen referred to is also on the left side near where your left foot would be if you were sitting on your tractor. The screen is behind a plate with three bolts. There is a cleanable screen behind the plate.....mine had some gunk in it. Hope this helps.......I really enjoy my 186d....hope you enjoy yours as well.:thumbsup::thumbsup:

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thnx alot jerrybob!

im having problems with mine think it has leaked out a bit, so i have to find out whats what (i have inheritade my yanmar and i have no papaers) =)

its a handy little tractor.. for now its a blizzard outside so ill have to wait a bit before a go out:thumbsup:

thnx again jerrybob!