MX5100F Transmission/hydrualic overheating

[tractorgo]

The trans/hydraulic fluid overheated on my MX5100F while brush cutting. There was no overheating of the engine. This was only discovered at the end of the cutting session (1 hr to 1.5 hours) when I saw the boot on the gear shifter had been unseated from the fluid/air expansion. I would guess the bottom of the gear shift shaft where the boot goes was around 140F. Definitely hot to the touch. I found that the transmission breather vent was blocked with dirt dauber mud. I thought I cleared the mud from the "C" shaped metal barb that the breather rubber hose connects to, but it seems I didn't clear the blockage completely. The hydraulic fluid overheated again on another brush cutting session with the same basic scenario of the rubber boot on the gear shifter being unseated and the base of the shifter being hot - the whole transmission case was around the same temp.

I used the air compressor to try and blow out the restriction - no success, rammed a piece of wire into "C" barb and nothing came out, tapped on it with a hammer and nothing. At this point I'm assuming moisture may have formed a hard rusted blockage inside the barb. I plan to spray some penetrating oil into the barb and see if that does anything.

Here are some questions I have...

1. Is there any reason not to disconnect the rubber breather hose from the barb while using the tractor and just reconnect it after use? The currently blocked barb is not letting anything get inside the rubber hose. The "OLD" style in the diagram below makes more sense to me from accessibility/maintenance, but I assume there were issues.

2. I have full synthetic hydraulic fluid in the tractor, but it looks like it thinned out some from the overheating. I will definitely replace the hydraulic fluid, but also have concerns about other parts in the hydraulic/transmission system. What should I be keeping an eye on for issues? I assume loss of hydraulic lift/jerkiness with the FEL, PTO power. There was probably a loss of PTO power (poor cutting) the second time it happened, but attributed it to worn blades. Has anyone else experienced this type overheating? What damage was done/repairs needed?

Thanks for any advice/comments!


Image from https://www.messicks.com/catalogs/kubota/mx5100f

 

[TheOldHokie]

The trans/hydraulic fluid overheated on my MX5100F while brush cutting. There was no overheating of the engine. This was only discovered at the end of the cutting session (1 hr to 1.5 hours) when I saw the boot on the gear shifter had been unseated from the fluid/air expansion. I would guess the bottom of the gear shift shaft where the boot goes was around 140F. Definitely hot to the touch. I found that the transmission breather vent was blocked with dirt dauber mud. I thought I cleared the mud from the "C" shaped metal barb that the breather rubber hose connects to, but it seems I didn't clear the blockage completely. The hydraulic fluid overheated again on another brush cutting session with the same basic scenario of the rubber boot on the gear shifter being unseated and the base of the shifter being hot - the whole transmission case was around the same temp.

I used the air compressor to try and blow out the restriction - no success, rammed a piece of wire into "C" barb and nothing came out, tapped on it with a hammer and nothing. At this point I'm assuming moisture may have formed a hard rusted blockage inside the barb. I plan to spray some penetrating oil into the barb and see if that does anything.

Here are some questions I have...

1. Is there any reason not to disconnect the rubber breather hose from the barb while using the tractor and just reconnect it after use? The currently blocked barb is not letting anything get inside the rubber hose. The "OLD" style in the diagram below makes more sense to me from accessibility/maintenance, but I assume there were issues.

2. I have full synthetic hydraulic fluid in the tractor, but it looks like it thinned out some from the overheating. I will definitely replace the hydraulic fluid, but also have concerns about other parts in the hydraulic/transmission system. What should I be keeping an eye on for issues? I assume loss of hydraulic lift/jerkiness with the FEL, PTO power. There was probably a loss of PTO power (poor cutting) the second time it happened, but attributed it to worn blades. Has anyone else experienced this type overheating? What damage was done/repairs needed?

Thanks for any advice/comments!

View attachment 181286
Image from https://www.messicks.com/catalogs/kubota/mx5100f

What do you think overheated hydraulic temperature would be?

What do you think normal hydraulic temperature should be?

How and were are you measuring your hydraulic temperature?

I think you have a vent ptoblem. I doubt you have an overheating problem.

Dan

 

[tractorgo]

What do you think overheated hydraulic temperature would be?

What do you think normal hydraulic temperature should be?

How and were are you measuring your hydraulic temperature?

I think you have a vent ptoblem. I doubt you have an overheating problem.

Dan

Thanks for helping me check my assumptions.

I don't have much experience with tractors, but I was surprised that the bottom of the gear shift was as hot as it was... After researching some, I probably shouldn't have been surprised by the temperature. I don't know the actual temperature and wasn't using temp measuring device. It could have been well above 140 F. I know I couldn't keep my hand on it for more than maybe second or two and I was no longer brush cutting at that time, so it may have cooled some. From researching a bit just now, the operating temp of the hydraulic/trans fluid can be about 100 F above ambient temp - so it very well could have been above 185 F, since the outside temp was about 85 F.

I understand that temperature increases proportionally with pressure in a constant volume system. How much the temp may have increased over normal operation, if any, until the rubber boot got unseated, I don't know.

An update on the blockage - After using some penetrating oil in the "C" barb I was able to finally clear the blockage with a piece of wire. I'm not sure how much the penetrating oil help, but it did appear some rust came out when I used a zip tie to try and knock more debris out.

 

[TheOldHokie]

Thanks for helping me check my assumptions.

I don't have much experience with tractors, but I was surprised that the bottom of the gear shift was as hot as it was... After researching some, I probably shouldn't have been surprised by the temperature. I don't know the actual temperature and wasn't using temp measuring device. It could have been well above 140 F. I know I couldn't keep my hand on it for more than maybe second or two and I was no longer brush cutting at that time, so it may have cooled some. From researching a bit just now, the operating temp of the hydraulic/trans fluid can be about 100 F above ambient temp - so it very well could have been above 185 F, since the outside temp was about 85 F.

I understand that temperature increases proportionally with pressure in a constant volume system. How much the temp may have increased over normal operation, if any, until the rubber boot got unseated, I don't know.

An update on the blockage - After using some penetrating oil in the "C" barb I was able to finally clear the blockage with a piece of wire. I'm not sure how much the penetrating oil help, but it did appear some rust came out when I used a zip tie to try and knock more debris out.

For context holding your hand on a 140°F surface for just 3 seconds will be very painful and you will suffer a lasting 3rd degree burn.

When you can MEASURE sump (atmospheric pressure) oil temps approaching 200° F you might start to worry. It does not seem you are anywhere close to that.

Right now I would be working on the vent problem thats popping the shifter boot off.

Dan