Can the hydraulic system get air locked after a fluid change

[Leonard malone]

I do know a guy that works for CAT. I wasn't sure if a diesel mechanic would be familiar with hydrostatic transmission.I will have to give him a call.I'll let you know how I make out. Thanks Len

 

[rScotty]

I do know a guy that works for CAT. I wasn't sure if a diesel mechanic would be familiar with hydrostatic transmission.I will have to give him a call.I'll let you know how I make out. Thanks Len

I think that if you tell him the type of transmission or show a picture of a cutaway HST he he can figure out it out. It is just one swash plate hydraulic pump driving another. Lots of hydraulic systems are similar to that.

Frankly, to me it didn't sound like an internal transmission problem at the start - though it might have gotten to that later.
It sounds like at the start either a control cable or more likely the hydraulic fluid is not getting to the transmission. If a good mechanic can't find the problem in a couple of hours then it can go to the dealer.

I've forgotten if we have a good schematic of your ck hydraulic system on this thread, but that would be a help to him as well.
rScotty

 

[oldnslo]

Is this the same thread where original poster asked about input shaft into the transaxle turning when trying to move the tractor? If yes after looking parts breakdown he could have fully functional hydraulics and transaxle not work if input shaft is not spinning or splines on input shaft are shot so shaft is turning but HST pump is not.

 

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If we recall, Len did state that the tractor felt a little wonky even before the fluid change.
Don’t know too much about his tractor age wise, used or new or any previous problems or over worked situations encountered.
The simple things such as air entrainment or suction leaks seemed to have been addressed.
I am wondering if the
pump is still making any noise or if the problem is related toward a pressure relief valve.
As Scotty has mentioned, there is an inclination of wanting this tractor before me so as to rip into it .
Can only wish the best for Len.

 

[rScotty]

Is this the same thread where original poster asked about input shaft into the transaxle turning when trying to move the tractor? If yes after looking parts breakdown he could have fully functional hydraulics and transaxle not work if input shaft is not spinning or splines on input shaft are shot so shaft is turning but HST pump is not.

That's right. Tractors often have several hydraulic pumps for different systems, and each can be fed in a variety of ways. So it is entirely possible for a FEL/3pt to work just fine while a HST doesn't move the tractor at all. Power steering is a world all of its own. Even PTOs can be fully hydraulic or hydraulically actuated. Sometimes - but not always - one part of a hydraulic system can affects the rest of the system too.

Half the problem here is we don't know the system. A mechanic often needs the work shop manual with its hydraulic flow diagram and hydraulic schematics in order to diagnose all but the simplest problems.

But the other half of the story is that given the flow diagrams - plus a pressure gauge with some fittings -finding a hydraulic problem suddenly becomes enjoyable mechanical work.
rScotty

 

[Leonard malone]

I'm posting some schematics . I have pages of diagrams on all the transmission components.

 

[Leonard malone]

My tractor is a 2006 ck 25 kioti

 

[rScotty]

I'm posting some schematics . I have pages of diagrams on all the transmission components.

Those diagrams are great. Did you ever replace that hose and clamps back on Feb. 1?

Are you still trying to do this yourself or going to find some mechanical help?

 

[Leonard malone]

I did change hose and clamp. I'm waiting to hear from a diesel mechanic . Hoping he will be able to come take a look. The nearest dealer with a real mechanic is 2 hrs away. That will be the next move if I can't get someone to come here to look at it.

 

[rScotty]

I did change hose and clamp. I'm waiting to hear from a diesel mechanic . Hoping he will be able to come take a look. The nearest dealer with a real mechanic is 2 hrs away. That will be the next move if I can't get someone to come here to look at it.

Typically, a mechanic will want to check what the symptoms are and experience them himself.

Then he will want to go over what you did and see if anything there has contributed to a problem. If he can't find something - and he may not - then the the next step is to get out your shop manual and check the hydraulic pressures.
There are standard test ports that he will spot immediately for the main tractor hydraulics on the main pump and on the FEL control.
Then with the aid of your workshop manual and those pictures you posted he can also find the ones for the HST system. Pressure values should be in the workshop manual.

The pictures also show a schematic - the diagram with hydraulic symbols. That is very good, because with pressures and that schematic then he can probably find the problem.

To do this in the best way, one of you will need a hydraulic gauge test kit and adapters - better ask if he has one to bring it.

If it is you doing the work, Amazon has hydraulic test kits. Look under "hydraulic test gauge kit". They aren't expensive. The challenge is getting the proper threaded adapter to fit your test port. Most of the hydraulics on the loader control valve are universal, but with the HST getting the right adapter is always a gamble.
rScotty

 

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Len
Is the pump still whining?
Is there any place close that could bench test this for you.
Alternative is to get a test kit Scotty mentioned and mount a gauge right after the pump if you have the room or an adaptor.

 

[oldnslo]

Len
Since this post in now 10 pages what is the problem you are experiencing and associated symptoms.

Is it just that the tractor will not move? If yes back to question of is the input shaft from the engine to transaxle turning when you are trying to drive the tractor? If that shaft is not turning you have a clutch problem..

 

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Len
Since this post in now 10 pages what is the problem you are experiencing and associated symptoms.

Is it just that the tractor will not move? If yes back to question of is the input shaft from the engine to transaxle turning when you are trying to drive the tractor? If that shaft is not turning you have a clutch problem..

What are you referring to as a “clutch” on an hst tractor?

 

[rScotty]

I don't know about Len's CK 25 Kioti, but some HST tractors do have a traditional clutch. So it isn't impossible - his might have a clutch.
I wouldn't have believed it either, but our M59 Kubota is a HST and it has a traditional clutch that looks like any other - left foot pedal and all. I have no idea why, but there it is.

Pushing the clutch petal down interrupts the power to the input transmission shaft just like on any manual shift - except in this case the transmission is not a manual, it is a HST.

Frankly I wish ours didn't have a foot clutch. I can't see a use for it, and having it puts both steering brakes on the right side next to the HST F/R pedal. You might think it is for the PTO, but the PTO has its own clutch.

 

[ptsg]

What are you referring to as a “clutch” on an hst tractor?

You can see the clutch on the OP's HST tractor on post #66. It's used mostly to engage/disengage the PTO.

I've wondered if the OP locked the clutch pedal down and forgot entirely about it.

 

[arrow]

You can see the clutch on the OP's HST tractor on post #66. It's used mostly to engage/disengage the PTO.

I've wondered if the OP locked the clutch pedal down and forgot entirely about it.

Or to change ranges.
All the “ clutch “ pedal is doing is operating a valve for fluid control.
There is no “disc/ pressure plate” as a real clutch would have.
A swash plate is acting to dictate flow pressure and direction but this involves pistons in a fixed or stationary plate.
Not seeing a clutch in the sense of what I know as a drive mechanism on an hst .

 

[arrow]

I don't know about Len's CK 25 Kioti, but some HST tractors do have a traditional clutch. So it isn't impossible - his might have a clutch.
I wouldn't have believed it either, but our M59 Kubota is a HST and it has a traditional clutch that looks like any other - left foot pedal and all. I have no idea why, but there it is.

Pushing the clutch petal down interrupts the power to the input transmission shaft just like on any manual shift - except in this case the transmission is not a manual, it is a HST.

Frankly I wish ours didn't have a foot clutch. I can't see a use for it, and having it puts both steering brakes on the right side next to the HST F/R pedal. You might think it is for the PTO, but the PTO has its own clutch.

Not as a drive mechanism in the traditional sense. There are some hsts that do not have a clutch pedal. There really is no need for one except it is simply cheaper to incorporate one for fluid volume control on our tractors rather than using electronic solenoids, sensors and relays.
What the clutch pedal does on an hst is to control what some call an “inching valve”..This valve is what is controlling fluid volume for specific things such as range changes or pto control.
The plungers on these valves should be all the way in.
I made mention of this adjustment previously and would be the first thing l would look at.
This tractor is almost 20 years old.
It’s gonna need stuff and the second thing l would have addressed is the pump.
There are too many things within that pump that can be compromised within 20 years.

 

[ptsg]

Or to change ranges.
All the “ clutch “ pedal is doing is operating a valve for fluid control.
There is no “disc/ pressure plate” as a real clutch would have.
A swash plate is acting to dictate flow pressure and direction but this involves pistons in a fixed or stationary plate.
Not seeing a clutch in the sense of what I know as a drive mechanism on an hst .

Yes, there is a conventional dry clutch. You can see it on post #66. It's there for the PTO. You don't really need a clutch to change ranges on an HST. Many HST tractors are like this.

I'll add a picture from the parts catalogue as well:

 

[oldnslo]

Or to change ranges.
All the “ clutch “ pedal is doing is operating a valve for fluid control.
There is no “disc/ pressure plate” as a real clutch would have.
A swash plate is acting to dictate flow pressure and direction but this involves pistons in a fixed or stationary plate.
Not seeing a clutch in the sense of what I know as a drive mechanism on an hst .

Arrow
The clutch is controlling the mechanical input from the engine to HST. It is not part of the HST transmission. On my Branson it controls the PTO like PTSG states and also disconnects all mechanical input from the engine. It also allows starting tractor without and mechanical power going to transaxle so engine turns over much easier in cold weather.

I have not seen a Kubota or Deere that have this feature but diagram posted by Len certainly looks like there is a clutch between engine and transaxle.

 

[arrow]

Arrow
The clutch is controlling the mechanical input from the engine to HST. It is not part of the HST transmission. On my Branson it controls the PTO like PTSG states and also disconnects all mechanical input from the engine. It also allows starting tractor without and mechanical power going to transaxle so engine turns over much easier in cold weather.

I have not seen a Kubota or Deere that have this feature but diagram posted by Len certainly looks like there is a clutch between engine and transaxle.

What you talk about is fluid control. From what I’ve seen on my brand is an input shaft connected to the crank with gearing. If the engine is turning, so is the input shaft. If it is not, the gearing is either stripped, bearing compromised or attachment failed. The control, speed and direction of the tractor is happening after that with valve/fluid regulation.
Some even use that pedal as a brake mechanism as to disrupt fluid volume to relieve pressure. It is what makes range changes easier and also controls live ptos.
Are you the seeing the swash plate? I’ve heard that referred to as a clutch.
Why would an hst need fingers, pressure plate and clutch disc as a drive if it’s relying on regulated pressured fluid delivery to move?