HST Problems

[Rockin' G Ranch]

HST on my L4740 has not worked right since getting it back from the dealer after an engine replacement. Also had them change the HST fluid and filters. Now I got this in an e-mail:
"We have ran some test on the tractor. The internal hydraulic pressure on the transmission is low. Book spec shows about, 4950-5680 psi, forward and reverse HST pressure. Actual pressure on your tractor is 2200 psi.

The transmission HST pump or motor has a failure. We will need to disassemble the transmission and overhaul the HST system to repair. We will put an estimate together for you."

The HST was working perfect before this work was done. Could they have damaged the HST by performing the other work? What does it cost to rebuild a HST? Thanks.

 

[nybirdman]

Under warranty? I would be contacting the district Rep.Yes they may have damaged the HST and not cheap to repair.

 

[crazyal]

I wonder if they will find out why it's bad when they remove it. Nothing comes to mind but if your oil drain was tampered with they may have done something to your HST as well.

 

[94BULLITT]

What is wrong with it, under powered? Is it under warranty?

 

[texasjohn]

an engine replacement and now HST pressure problems?? Man, that's major.

What happened to require the engine replacement...sure hope it was under warranty?

You say it was working fine before the work was done...did something happen that not only affected the engine, but HST as well??

Am assuming that hours on tractor are low....under 1000, more likely under 500??

Really hard to understand how these kind of failures could have occurred on such a new tractor. Have heard nothing of this sort before on TBN for this or any other Kubota HST tractor. Am not a mechanic, thus can't say if engine replacement/work could have caused low HST pressure.

OK...answered my question....you had extreme misfortune to lose oil drain plug, causing engine replacement need...as discussed in this thread...http://www.tractorbynet.com/forums/kubota-owning-operating/252151-cant-believe-happened-3.html

I'm guessing that your HST problem is related to the engine freeze up problem you had.

Man, you've really had problems...throttle sensor also went bad...gosh, only good news is that you have insurance...hope it helps!!

 

[SPYDERLK]

I'm guessing that your HST problem is related to the engine freeze up problem you had.

Could you please develop this a bit. I can see no way that an engine stalling/stopping due to internal issues would affect a trans. To me it comes down to 1 of 2. Oil and filter change, or towing too far in gear.
larry

 

[texasjohn]

OP had oil plug fall out, engine overheated and seized up. Fixes since have included new radiator, new engine, new throttle sensor, change HST oil and filter. These are what the OP has discussed in TBN threads.

And, now, HST pressure which was apparently OK prior to oil plug problem is now less than half what it should be. True, it's been a couple of months since engine replacement, but I'm speculating that it would take a while to become convinced there was some sort of HST problem and take it back to dealer. Speculation again, is that dealer simply replaced fluid and filter, didn't at that time test HST psi, and returned it to OP. Seeing no appreciable improvement, back to dealer who looked into it further and has diagnosed low pressure.

That's lots of speculation, I admit, and, I further admit that it's a little hard to put a finger on relationship between engine seize up and low HST pressure. Nevertheless, somewhere in the process of engine failure, replacement, HST maintenance the problem arose.

Hard to see how HST maintenance with new oil and filter would cause the problem.
Not being a Kubota mechanic, I can't say if an overheated engine would fry things in the HST as well.
Nor do I understand the engine/HST interface which certainly was exposed during the engine replacement...I speculate that there is a finite probability that a problem could have been introduced during the engine replacement....full engine replacement is extremely rare...likely this was the very first one that that mechanic has ever done.

Net is that I feel the OP's pain.....he has a fantastic tractor and thru a set of terrible events he has not been able to enjoy it for months and months.

I hope he gets this problem behind him soon, that it is the last one to arise, and that he's able to enjoy his tractor failure free for years to come.

 

[Rockin' G Ranch]

Just to clear things up here is the entire history:
1. All was working GREAT until the oil plug fell out, oil drained out and engine froze up.
2. Dealer came out and winched tractor on trailer (in N).
3. Full engine replacement and HST filter and fluid change. Also replaced clutch since it was at 50% worn. Found faulty Throttle Sensor.
4. Dealer delivered it with Throttle Sensor backordered. Dealer said it was OK to use.
5. I tried to use it but the HST was terrible - would not get out of "turtle" gear and had NO power. Engine ran great!
6. Dealer picked up tractor a few days later. Replaced Throttle Sensor and all seemed to work driving it around the barn.
7. Used it for 1 day with HST not holding with foot off pedal. Sometimes could not restart tractor without bumping pedal to put in N.
8. Tractor went back in "turtle" gear and again lost power.
9. Dealer picked up again and found HST pressure low.

So I think the oil plug falling out was vandalism so dealer thinks other things were done to the tractor also. Insurance covered the engine replacement so hopefully it will also cover the HST problem.

 

[texasjohn]

Thanks for the detail.....all sounds logical although unfortunate in the extreme.

The good news is that you and your dealer seem to be working thru this and the dealer and insurance are doing their best to resolve the problem quickly for you.

I commend your tone of reasonableness..... so refreshing and what I expect on TBN....I really hate the rancorous posters who rail at their dealers without sufficient reason, to my way of thinking.

I think this is all going to work out properly in the end and you will have a super tractor to enjoy for years!

 

[TripleR]

Thanks for the detail.....all sounds logical although unfortunate in the extreme.

The good news is that you and your dealer seem to be working thru this and the dealer and insurance are doing their best to resolve the problem quickly for you.

I commend your tone of reasonableness..... so refreshing and what I expect on TBN....I really hate the rancorous posters who rail at their dealers without sufficient reason, to my way of thinking.

I think this is all going to work out properly in the end and you will have a super tractor to enjoy for years!

Agree,, so much better than the "I'll never buy another Kubota, Kioti, John Deere etc." so often seen.