Hydraulic PTO issues ..... flow divider???

[RickB]

At first I simply thought about a leak at the pto valve.. but the air bubbles thing.. it's deffinately getting in on a suction side.. not on a pressurized leak / side.

soundguy

A vigorous leak from the clutch assembly spraying oil around the inside of the housing and agitating the oil will aerate it nearly as well as a suction leak.

If both the remote valves and PTO clutch supply is drawn through a common suction and remote flow is not affected materially, there isn't likely to be air getting into the suction circuit until the entire body of oil is aerated. A worn pump or leaking pressure circuit will be exacerbated by heated oil. A suction problem will likely exist at most all oil temps, and may well be worse with cold oil.

 

[Soundguy]

I think I might run a remote thru an open hose into a bucket at the point the pto fails to see if the remote has the bubbles too.

that should be telltale given your analysis.

soundguy

 

[Mechanos]

I think I might run a remote thru an open hose into a bucket at the point the pto fails to see if the remote has the bubbles too.

that should be telltale given your analysis.

soundguy

I will try that this afternoon.

I am now leaning away from the oil temp having any affect on things since I can shut the tractor off and let it sit for a few minutes after the PTO quits and then fire it back up and the PTO will work for a while again. The oil is still virtually the same temp as it was when the PTO quit the first time. I am thinking that letting the tractor sit for a few minutes gives the air a chance to get of the oil. I sure hope this is it.... but I won't know until next week when the new rubber couplers come in and I have a chance to get them installed.

 

[Mechanos]

The new rubber couplers for the suction line came in today. Picked them up after work. Drained the oil and pulled the old couplers off and installed the new ones. The old couplers were hard as a rock whereas the new ones were soft and flexible.

Since I had to drain the oil to change the couplers, I removed the strainer out habit.... anytime I drain the oil, there is no reason not to go ahead and check/clean the strainer. Since there is very, very little run time on this batch of oil... only an hour or two with most of that time spent diagnosing the PTO problem, I was quite shocked and concerned at the amount of tiny metal flakes found on the strainer and in the amount of oil that drained out of the transaxle after pulling the strainer. There was a fair amount. I know it's hard to quantify "quite a bit", but it is way more than should be ther after just an hour or two of operation. Other and one or two laps around the property, all of that time has been spent with the tractor sitting still while I worked on the PTO issue.

I went ahead and put it all back together and tried the PTO.... same results as always. Well, I guess there was one little twist that was different this time. Normally, the PTO would engage at around 100psi or above. I was reading 110psi on the gauge with the PTO turning. When I cycled the PTO lever off, it took an extended period of time for the pressure to drop to zero instead of dropping immediatly like it had been doing. When I cycled the PTO lever back to the ON position, the circuit built 110psi, but the PTO would not turn.

Based on my findings tonight, I'd say that there more than likely something internal that is jacked up. Given the amount of metal I found in the strainer, it has me thinking that the PTO clutch pack is wasted. I feel that I have no choice now but to remove the transaxle and disasseble it for inspection. :mur:
Either that or drive it off into the pond and forget I ever bought it. :laughing:

 

[dfkrug]

Given the amount of metal I found in the strainer, it has me thinking that the PTO clutch pack is wasted. I feel that I have no choice now but to remove the transaxle and disasseble it for inspection.

That's a good guess. At least you won't have to split the tractor in two,
in the conventional sense. The frame rails are just bolted to the sides of
the gearbox. I would like to see how the PTO clutch/brake system is built,
internally.

 

[Mechanos]

That's a good guess. At least you won't have to split the tractor in two,
in the conventional sense. The frame rails are just bolted to the sides of
the gearbox. I would like to see how the PTO clutch/brake system is built,
internally.

Might as well consider it splitting the tractor in two....

Actually the frame rails are bolt to the sides and to the front of the transaxle. To get to the bolts on the front of the transaxle, I'll have to remove the hydro trans. To remove the hydro, I'll need to remove the driveshaft. To remove the driveshaft, I'll have to remove the fuel tank. Then there is every one of the linkages that connects to anything on the transaxle. I'm not sure ... but it might even be worse than splitting the tractor in the conventional sense. It's more like disassembling the tractor to remove the transaxle.

Since I don't have Japanese hands or Japanese tools, I'm probably looking at 15 to 20 manhours just to get the transaxle removed from the tractor. It definately going to take some time, test my resolve and test my ability to not to put a gun to my head.

 

[dfkrug]

To remove the driveshaft, I'll have to remove the fuel tank.

As I recall, when you remove all the sheet metal, you can detach the
driveshaft at the U-joint just above the filter between the frame rails. Or
you can disconnect the shaft at the rubber coupling below the fuel tank
without removing it. That allows you to keep the HST/gearbox all together.

If you take all the linkages out, you can toss the levers used as a
mechanical interlock system for the go-pedals.

 

[JohninCT]

Based on my findings tonight, I'd say that there more than likely something internal that is jacked up. Given the amount of metal I found in the strainer, it has me thinking that the PTO clutch pack is wasted. I feel that I have no choice now but to remove the transaxle and disasseble it for inspection.

Maybe I'm missing something, but how would a bad PTO clutch cause the PTO pressure to be low? If the service manual said to shim the PTO delay relief valve to increase the pressure setting why don't you try this first?

 

[Mechanos]

Maybe I'm missing something, but how would a bad PTO clutch cause the PTO pressure to be low? If the service manual said to shim the PTO delay relief valve to increase the pressure setting why don't you try this first?

Hmmm..... now there's an idea. Oh yeah, I already tried that back in post #1. :laughing:
A worn out clutch could cause the pressure to drop if the friction disks have lost too much material. According to a service tech I talked to, he said that if the frictions are too thin, it can allow the clutch piston to travel too far out of it's bore and cause the o-ring to partially loose it seal and allow oil to bleed by.

As I recall, when you remove all the sheet metal, you can detach the
driveshaft at the U-joint just above the filter between the frame rails. Or
you can disconnect the shaft at the rubber coupling below the fuel tank
without removing it. That allows you to keep the HST/gearbox all together.

If you take all the linkages out, you can toss the levers used as a
mechanical interlock system for the go-pedals.

You have to loosen the clamp bolt on the u-joint yoke at the transmission, but you have to slide the d-shaft forward to slip it off the trans input shaft. In order to slide it forward you have to take it loose at the rubber coupler. With the engine still in place, the only way to slide it far enough forward is to angle it upwards and to the side. Even then, it has to angle up higher than the bottom of the fuel will allow, so I have to pull the tank. The HST has to be removed just to get to some of the bolts that hold the transaxle to the frame..... unless I could one of those nifty Japanese wrenches that those little handed guys must have had to put this thing together.

Believe me.... I just put half of those things back in the tractor. If I didn't have to remove all that stuff, I wouldn't. It was not fun putting it in.

 

[97tacoma4x4]

Did you ever find out what the problem was?