Help troubleshooting hydraulic issue

Hydraulics is not my strong suit so I was wondering if you guys could help me troubleshoot my tractor. My 3 point lift is moving slow and doesn t always lift all the way up, it will usually stop lifting halfway up. Tractor is an MF 150 gas (tried posting in the MF forum but not a lot of action so I thought I d ask my N brothers).

At first I thought I had water in the fluid because it was white in color but upon closer inspection the white color is actually due to tons of small air bubbles in the fluid. What would cause air bubbles in the fluid? Looking at the book it looks like this tractor has a hydraulic filter so I was wondering if a clogged filter could cause this.

Another possibility that I was wondering about was the book says the system holds 8 gallons of hydraulic fluid. When I changed it only 6 gallons came out and when I refilled it with fluid it read full on the dipstick after I put in 6 gallons. I pulled the bottom bolt out of the inspection cover and fluid came out.
 
(quoted from post at 13:06:44 01/14/20) Here's a quick video showing the issue:

https://youtu.be/HqAgDsP6bTs

I know nothing about these machines but the WWW can make you an expert in no time ;-)

My first WAG would be an intake restriction and the entrained air is the result of cavitation. Have you checked/cleaned the intake strainer and port? Here is a video that shows pump disassembly/removal. The strainer is shown at around 30 seconds. That one had accumulated a fair amount of gunk in the port.

MF 135 Hydraulic Pump Service

TOH
 
(quoted from post at 11:09:31 01/14/20)
(quoted from post at 13:06:44 01/14/20) Here's a quick video showing the issue:

https://youtu.be/HqAgDsP6bTs

I know nothing about these machines but the WWW can make you an expert in no time ;-)

My first WAG would be an intake restriction and the entrained air is the result of cavitation. Have you checked/cleaned the intake strainer and port? Here is a video that shows pump disassembly/removal. The strainer is shown at around 30 seconds. That one had accumulated a fair amount of gunk in the port.

MF 135 Hydraulic Pump Service

TOH

I have not opened up the top cover yet but I appreciate you pointing me in the right direction. I think I'll start there and take a look at how the strainer looks.

Could low hydraulic fluid cause this issue as well? I'm still wondering why the service manual says an 8 gallon capacity but it only took 6 gallons when I changed the fluid.
 
(quoted from post at 17:12:52 01/14/20)
(quoted from post at 11:09:31 01/14/20)
(quoted from post at 13:06:44 01/14/20) Here's a quick video showing the issue:

https://youtu.be/HqAgDsP6bTs

I know nothing about these machines but the WWW can make you an expert in no time ;-)

My first WAG would be an intake restriction and the entrained air is the result of cavitation. Have you checked/cleaned the intake strainer and port? Here is a video that shows pump disassembly/removal. The strainer is shown at around 30 seconds. That one had accumulated a fair amount of gunk in the port.

MF 135 Hydraulic Pump Service

TOH

I have not opened up the top cover yet but I appreciate you pointing me in the right direction. I think I'll start there and take a look at how the strainer looks.

Could low hydraulic fluid cause this issue as well? I'm still wondering why the service manual says an 8 gallon capacity but it only took 6 gallons when I changed the fluid.

Anything that starves the pumps intake oil supply could cause cavitation. Looking at that video the pump is at the bottom of the case and I would think the oil level would have to be very low to cause starvation. But what do I know - I just watched a little youtube....

TOH
 
(quoted from post at 14:28:51 01/14/20)
(quoted from post at 17:12:52 01/14/20)
(quoted from post at 11:09:31 01/14/20)
(quoted from post at 13:06:44 01/14/20) Here's a quick video showing the issue:

https://youtu.be/HqAgDsP6bTs

I know nothing about these machines but the WWW can make you an expert in no time ;-)

My first WAG would be an intake restriction and the entrained air is the result of cavitation. Have you checked/cleaned the intake strainer and port? Here is a video that shows pump disassembly/removal. The strainer is shown at around 30 seconds. That one had accumulated a fair amount of gunk in the port.

MF 135 Hydraulic Pump Service

TOH

I have not opened up the top cover yet but I appreciate you pointing me in the right direction. I think I'll start there and take a look at how the strainer looks.

Could low hydraulic fluid cause this issue as well? I'm still wondering why the service manual says an 8 gallon capacity but it only took 6 gallons when I changed the fluid.

Anything that starves the pumps intake oil supply could cause cavitation. Looking at that video the pump is at the bottom of the case and I would think the oil level would have to be very low to cause starvation. But what do I know - I just watched a little youtube....

TOH

I agree, I just watched the video again and he mentioned that sometimes you can actually change that filter through the side cover so it'll be worth a shot to try that before I pull the top cover.
 
Everyone wants a fast answer and a quick fix on hydraulic issues. I have been working on tractors for 25 years and have all sorts of factory tools and homemade ones to diagnosis and repair them. Sometimes I still get stumped. Get a good service manual for your tractor and read and study it before jumping in. Most have a troubleshooting guide. You need to check pressures and go through the diagnostics before you tear the thing apart. Sometimes you get lucky and find a simple fix. I usually don't, I have a tendency to get only the ones everyone else has given up on.
 
(quoted from post at 20:01:29 01/14/20)
(quoted from post at 14:28:51 01/14/20)
(quoted from post at 17:12:52 01/14/20)
(quoted from post at 11:09:31 01/14/20)
(quoted from post at 13:06:44 01/14/20) Here's a quick video showing the issue:

https://youtu.be/HqAgDsP6bTs

I know nothing about these machines but the WWW can make you an expert in no time ;-)

My first WAG would be an intake restriction and the entrained air is the result of cavitation. Have you checked/cleaned the intake strainer and port? Here is a video that shows pump disassembly/removal. The strainer is shown at around 30 seconds. That one had accumulated a fair amount of gunk in the port.

MF 135 Hydraulic Pump Service

TOH

I have not opened up the top cover yet but I appreciate you pointing me in the right direction. I think I'll start there and take a look at how the strainer looks.

Could low hydraulic fluid cause this issue as well? I'm still wondering why the service manual says an 8 gallon capacity but it only took 6 gallons when I changed the fluid.

Anything that starves the pumps intake oil supply could cause cavitation. Looking at that video the pump is at the bottom of the case and I would think the oil level would have to be very low to cause starvation. But what do I know - I just watched a little youtube....

TOH

I agree, I just watched the video again and he mentioned that sometimes you can actually change that filter through the side cover so it'll be worth a shot to try that before I pull the top cover.

With your symptoms and having seen that video that is where I would start. You notice he also said that filter can be a PITA to get out from the inspection cover.....

TOH
 
(quoted from post at 17:45:14 01/14/20)]

With your symptoms and having seen that video that is where I would start. You notice he also said that filter can be a PITA to get out from the inspection cover.....

TOH

I just did some reading in my service manual and it looks like with my tractor I'll have to forget about trying to get the filter out through the side cover. Mine is different from the one in the video, mine has Independent PTO so the easiest option to change the filter is going through the top cover. Because it has two pumps the procedure to remove the pumps is different as well, they recommend splitting the tractor.
 
(quoted from post at 17:28:21 01/14/20) Everyone wants a fast answer and a quick fix on hydraulic issues. I have been working on tractors for 25 years and have all sorts of factory tools and homemade ones to diagnosis and repair them. Sometimes I still get stumped. Get a good service manual for your tractor and read and study it before jumping in. Most have a troubleshooting guide. You need to check pressures and go through the diagnostics before you tear the thing apart. Sometimes you get lucky and find a simple fix. I usually don't, I have a tendency to get only the ones everyone else has given up on.

Yeah, I have a feeling it won't be an easy fix. I did buy a factory service manual, parts book, operators manual and I&T manual so I have plenty of reading material before I turn any wrenches.
 

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