YM1510 Power Shift Slipping

[dgeezer]

I've been lurking aeoind here a couple weeks, but now I need some specific help.

I recently purchased a Yanmar YM1510. I've only used it a few (maybe 10) hours. It was working great and then the transmission and/or clutch started slippong so badly that the travtor won't even move.

yesterday, with info from this site, I cleaned the hydraulic system screen and changed the oil in the hydraulic system. I am assuming that the transmission and rear hydraulocs are all the same. This didn't seem to make any difference. The tractor will still move a little but it acts just like a car with a badly slipping automatic. I drove it downhill a ways from my barn after changing the fluid but it wouldn't come back up the slight incline on it's own. I had to tow it back to the barn with my pickup. One other weird thing I noticed was when I accidentally left it in gear, the rear wheels were locked upand wouldn't turn at all.

is there any hope for my yanmar?

 

[winston1]

Is your clutch adjusted properly. If you put a mower or something on will the pto slip? If the pto slips I believe it would be your clutch. If it doesn't I think it would be in the power shift. When left in gear the wheels shouldn't turn.

 

[dgeezer]

I don't have any PTO attachments. I thought the same thing about testing the PTO and that would eliminate the clutch as the culprit. I've tried to think of a way to lock down the PTO shaft that wouldn't risk killing myself. I can forsee pipe wrenches flying through the air....

There is a bit of slop in the power shift linkage but I think that I should be able to find a forward gear.

 

[California]

Don't try to restrain the pto, that will kill you. You might try looking back at the pto as you let the clutch out.

Actually these will coast, in gear, engine off. It's not the same as a straight mechanical transmission. The clutches inside the transmission are forced into engagement by hydraulic pressure, and the transmission's pump (separate from main hydraulics) is driven by the transmission input shaft. If that input isn't turning, no pressure, clutches disengaged. This may suggest the regular clutch is broken somehow and is not driving the transmission.

I'm baffled by 'rear wheels locked up'. Anybody got any ideas?

 

[dgeezer]

Well, I did decide thattrying to lock the PTO would be a bad idea. However the PTO does turn when I engage it and then let out the clutch and it stops when pish down on the clutch. The tractor will move but any kind of load stops it. If I put on the brakes or drop the blade on the 3 point hich it immediately stops without slowing down the engine. The scrape lade would easily lift the front wheels if I hit a big root or let it dig too deep, before this problem started.

Ok, I see the hydraulic pump mounted on the engine drives te lift for the 3 point hitch and not the transmission. The lift works fine.

 

[HoyeTractor]

When you put on the brakes and the tractor stops moving does the PTO shaft continue to spin?

Aaron
Hoye Tractor Parts
Contact Us
(940)592-0181

 

[dgeezer]

I think so but I'm not absolutely sure. I will check this tonight.

 

[California]

Here's some theory that may help you troubleshoot:

The 3-speed transmission including the pto is all direct mechanical connection through the clutch to the engine, in principle identical to any stick-shift vehicle.

Then behind that 3-speed (in theory - mechanically the are all stuffed in the same container) the Powershift, a second transmission, is between the 3-speed and the rear axle.

One thing this implies is that if you can halt the tractor with the brakes, still in gear, and the pto is still turning, then power is being sent to both the pto and the Powershift but it isn't coming out the Powershift's output side. I assume its hydraulic-actuated clutch packs are the only part that could slip without horrible grinding noise and since the failure is sudden, this points to hydraulic pressure lost - a blown seal, bad pump, cracked housing, maybe just a blocked hydraulic passage.

On the other hand if the brakes halt the tractor (in gear) and the pto stops, then no power is coming out of the main transmission. Assuming it isn't noisy, then the main clutch is the only component related to the front transmission that could slip quietly while the pto stops.

This is all just armchair theorizing, I hope it helps a little.

 

[dgeezer]

Yes. The PTO keeps turning, and apparen.tly at the same speed whether the tractor is moving or not. It seems to have a slightly more positive engagement in re erse rather than any of the forward gears.

I can get the ttactoe moving in gear and stop it with the brakes and the pto keeps spinning.

btw, please excuse my spelling. This has all been posted from my cellphone on the farm...

 

[normde2001]

There is something called a "delay relief valve spring" that breaks and causes your problem. Not sure where it is but it's actually 2 compression springs, one inside the other, and they say it's a really easy repair.

Re: Slow Shifting YM276_
I have a 186D that had the same problem. I will discribe the fix on mine hoping yours will be similar. Sit on the seat and look straight down between your legs (not at yourself, the tractor)and under the cover is the power shift regulator case ( I have the column shift). At the rear of the case is a diamond shaped cover with two bolts. Remove the bolts and screw one into the end of the sleeve inside and carefully pull out the sleeve. Using needlenose or whatever means remove the relief valve and holder (there are shims inside, don't lose them). Behind all that are two springs, a smaller one inside a larger one. If you can get them out, you should see probably the larger spring is broken (compress it with your fingers, my had a hairline crack). Buy both springs (since they aren't expensive) from a Yanmar dealer. Don't buy one from the hardware that looks just like it (trust me). Replace everything the way it was, check the o-ring on the first sleeve you pulled out for damage and get one if needed. Hopefully you won't have to pull the whole case off. If you do, you need another gasket. This assembly regulates the pressure for the shift clutches and delays the shift so your neck doesn't snap while shifting. The broken spring prevents the proper pressure build up for shifting. I discovered this after the filter cleaning and oil change. I figured it out from my service manual. I hope this fixes it for you. It won't hurt to run it this way, it just won't shift well.

Skin