345 trans slipping

[cliffblue]

I have gotten the hand me down 345 with the 18hp 590v in pretty good shape except after changing both hydraulic filters and oil in the transmission, it slips under load. When using the yard vac, it won't back up against any real grade and struggles in forward against hills. At 1287 hours I think it probably wasn't maintained very well before I got it. The question is, with the factory tech manual in hand, do I attempt to overhaul it or opt for another trans with low hours? I have found a few on eBay under $1000. Opinions?

 

[bruceatlam]

You're sure that it doesn't need a new drive belt??? Check it if you haven't already done so.

If it were me, I would rebuild what I have in hand. I don't think that 1,300 hours is too many at all for that trans.

 

[cliffblue]

New drive belt and idlers. I felt like the trans should still be ok at 1287 hours but I don't really know. You can fully press the reverse pedal and you can hear the hydraulic whine real good when it doesn't want to back up. Is there a rebuild kit or will I need to just open it up and start looking for bad parts? The manual does go into a lot of detail, but it will be time consuming. Thanks for the input. Cliff

 

[bruceatlam]

Did you drive it at all B4 you changed the filters, drive belt and fluid?? Was it the same B4 as it is now after?? You said it was a "hand me down". I suspect you know the PO. Can he shed any light on the current behavior?? Did it drive like that for him??? Was the new drive belt a JD belt??? Is the power steering OK?? How about the deck lift --- is that OK??

I'm not the trans expert by any means. Far as I know there's no kit. I'm willing to be wrong here but it sounds like other than the trans to me. The main hydraulic filter is directional; it is installed correctly??

Sorry I can't help you more. Mine will only whine if I try to move it with the brake set.

 

[cliffblue]

Hey Bruce
The 345 came from my neighbor. His company did facility maintenance. He left it there for years to mow. Probably never had anything behind it. The yard vac is pretty heavy, but I feel the mower should pull it ok. I went through it and replaced everything with JD parts. He did put a set of chevron tractor tires on it. That and the twin cyl engine is why put it on the yard vac. My GT275 has 500 hours on a factory short block but I bought it used with a blown motor and no hour meter back in 01. I haven't used it with the vac bc of the single cyl 17HP, but I might need to try it. I expect the trans are similar if not identical. I'll see how it pulls it. I don't believe the belt is slipping. The inline filter uses different size fittings on each end. You couldn't install it backwards if you wanted to.

 

[cliffblue]

Oh yeah, the steering and deck lift seem to work perfectly. I did drive it before a very short time and not pulling the vac. BTW, the test in the manual for trans tightness is to put 400lbs on the back and butt it against an immovable object and spin the tires on concrete. After removing the hood and front trim of course. I promise the vac is probably 200-250lbs at most. I will also quiz my neighbor.

 

[bruceatlam]

Let us all know if your neighbor can shed any more light on the subject.

Yeah, I read that transmission efficiency test protocol. Sounds pretty harsh to me; I'll try that some day, but I'm not sure that mine could pass that one.

 

[cliffblue]

I thought so too.

 

[oldnslo]

Does the 345 tons have relief valves built in or does it count on the tires spinning? If built-in relief you could be a max torque for that tranny with good tires and the extra weight.

 

[bruceatlam]

Yes, there are a couple of internal relief valves --- that could be a possibility. When that relief opens the oil dumps to tank. That would account for loss of performance. As far as that transmission efficiency protocol is concerned, I guess the assumption is that the tires will spin before the relief opens. It's not a high pressure system --- 36 psi if I recall correctly.

 

[cliffblue]

Correction on weight added to rear of tractor for transmission efficiency test. The correct weight is 168 lbs with a 200 lb operator.

 

[Flying MXZ]

New drive belt and idlers. I felt like the trans should still be ok at 1287 hours but I don't really know. You can fully press the reverse pedal and you can hear the hydraulic whine real good when it doesn't want to back up. Is there a rebuild kit or will I need to just open it up and start looking for bad parts? The manual does go into a lot of detail, but it will be time consuming. Thanks for the input. Cliff

Don't you let off these hydrostatic transmissions to go up steep grades?

 

[cliffblue]

I'm not sure I understand your question. If I nose down and need to reverse, it does not want to go. As the trans gets warmer, even less so. We're not talking serious grade here. Forward is better but still not strong. The manual does not consider any part except the pumps with this problem. In checking one site only, looks like a lot of unavailable parts involved. There are rebuilding or rebuilt swap sites out there. Anybody try this?

 

[Flying MXZ]

Ok, sounds beyond what I know. I think to go up steep hills with a hydrostatic transmission you don't want to push the peddle down all the way. Let off to lose speed, but gain "power".

 

[cliffblue]

Hmmm no

 

[cliffblue]

Hmmm no

not with my type of tractor

 

[bruceatlam]

Cliff --- I know that you don't want to hear this and I'll own that I could be wrong, BUT, this sounds like a loose/worn/wrong/installed wrong drive belt problem to me. You said that you bought all JD parts so I assume that you have the right belt. When you start to write about lack of power going up/down any little hill, I think immediately about living through that same problem when my main drive belt is worn out. That's exactly how my hydro behaves ----------

Sorry ---- I won't mention it again.

 

[cliffblue]

Hey Bruce, no problem. I appreciate the interest. While the belt is the correct one and new, I did run into the differences of belts for the 345 under 70000 vs 70001 and up. The early models <70000 like mine, use a conventional v belt design. Later they used a double v type that used flat idlers for both sides of the belt.
One reason I lean toward trans hyd problems, is when I have to push the pedal down all the way to get motion due to a grade, the trans really whines that hyd whine. If I had belt slippage, I don't think it would really whine like that. I had one summer on it when I changed the in line filter after starting on the vac in the fall. Everything underneath still looked ok. Like you, I'm no guru. I'm just looking at options. Thanks again for taking the time.

 

[bruceatlam]

Well if you're convinced that the problem is internal to the pump, then the reference to "whine" leads me to relief valves. See post #9. There are two in there -- they're both available --- one from JD at about $60 and from from an OEM parts seller for about $50. Both new at a total of $110. If I were you, I think that I would buy them and then set about to tear it down and clean it up well and replace those relief valves. If you find something else along the way --- so be it. There are other reasons to lose pressure but I don't think that they would produce the "whine".

What did you neighbor say?? Did he notice that behavior when he owned it??

 

[oldnslo]

Cliffblue,
I would be a little surprised if it is a slipping belt since the operation of the transmission changes with temperature. HST transmission function getting worse with temperature points towards a failing component in the tranny itself. In looking at the parts break down on the JD site I could not see any system relief valves in the HST (trans-axle). This would indicate that the design of this machine was for the wheels to spin to limit system pressure. NOTE: JD may have an option for work port reliefs on the HST. This also appears to be a semi-sealed trans-axle assembly so there is limited heat rejection capabilities so running the HST at higher loads causes higher leakage which translates to higher heat dissipation required. Higher temperature means thinner oil which leaks more which causes even more heat...