Omg,what went wrong,filter ruptured

torch · Dec 15, 2017

Does your B1750 have power steering?

I can't find a diagram for your particular model, but I'm looking at the hydraulic flow diagram for a B1700 which may be similar. On that model, the oil filter is on the HST charge pump "low pressure" circuit, rather than the suction side of the pump. The discharge from the power steering pump (fed through a priority valve from the high pressure main hydraulic pump) also joins that flow.

The charge pump circuit pressure is limited by a relief valve set to 71psi max. Automotive oil filters regularly handle that sort of pressure and the hydraulic oil filter is basically the same sort of design, so that shouldn't be a problem. However, if the relief valve stuck closed for some reason (eg: frozen moisture) then the potential is there to apply high pressure to that circuit if the loader or 3PH was in use (ie:centre of control valve was no longer open).

al m · Dec 15, 2017

torch said:
Does your B1750 have power steering?

I can't find a diagram for your particular model, but I'm looking at the hydraulic flow diagram for a B1700 which may be similar. On that model, the oil filter is on the HST charge pump "low pressure" circuit, rather than the suction side of the pump. The discharge from the power steering pump (fed through a priority valve from the high pressure main hydraulic pump) also joins that flow.

The charge pump circuit pressure is limited by a relief valve set to 71psi max. Automotive oil filters regularly handle that sort of pressure and the hydraulic oil filter is basically the same sort of design, so that shouldn't be a problem. However, if the relief valve stuck closed for some reason (eg: frozen moisture) then the potential is there to apply high pressure to that circuit if the loader or 3PH was in use (ie:centre of control valve was no longer open).

You have prob hit the nail on the head,it does have power steering,it was a very cold night (maybe coldest of the year) and I did lift the loader arms just before I noticed the issue.

torch · Dec 15, 2017

al m said:
You have prob hit the nail on the head,it does have power steering,it was a very cold night (maybe coldest of the year) and I did lift the loader arms just before I noticed the issue.

And I may be way off. I stress that I am not familiar with that machine and I am looking at a diagram for another machine in the hope that the design principle is similar.

That said, your comment raises another possibility. The diagram I refer to shows the relief valve after the filter. All oils, Kubota "Premium" UDT and synthetics included, thicken in the cold. Attempting to pump cold oil through a 10 micron filter mesh may have been enough alone, even if the relief valve was functioning perfectly.

Check out this thread comparing hydraulic tractor oils. Note the differences in pour points for various oils (on page 2, there is evidence the Kubota premium UDT available in Canada has a pour point of -57°C).

Obviously there is a wide range of performance beyond just meeting Kubota's minimum requirements. I'd suggest researching the cold weather specifications of the fluid you used. You may want to use something else in the next change. In the meantime, on or after cold nights, I'd let the tractor run at fast idle for a while before revving it up and getting to work. The pumps run constantly, so they should warm the oil a bit just by the friction of circulating it.

But that's just my 2¢ and I may be way off base on this.

al m · Dec 15, 2017

torch said:
And I may be way off. I stress that I am not familiar with that machine and I am looking at a diagram for another machine in the hope that the design principle is similar.

That said, your comment raises another possibility. The diagram I refer to shows the relief valve after the filter. All oils, Kubota "Premium" UDT and synthetics included, thicken in the cold. Attempting to pump cold oil through a 10 micron filter mesh may have been enough alone, even if the relief valve was functioning perfectly.

Check out this thread comparing hydraulic tractor oils. Note the differences in pour points for various oils (on page 2, there is evidence the Kubota premium UDT available in Canada has a pour point of -57°C).

Obviously there is a wide range of performance beyond just meeting Kubota's minimum requirements. I'd suggest researching the cold weather specifications of the fluid you used. You may want to use something else in the next change. In the meantime, on or after cold nights, I'd let the tractor run at fast idle for a while before revving it up and getting to work. The pumps run constantly, so they should warm the oil a bit just by the friction of circulating it.

But that's just my 2¢ and I may be way off base on this.

Stuck in my mind,the loader came of a tractor that was in a fire,some of the hydraulic hoses were burnt off,and in wondering if ther may have been moisture in the valve or cylinders that may have contaminated the system. I also have no idea what the oil in the loader cylinders may have been. I hope to get it good and warm this weekend,and drain the system and refill with Kubota oil.

D2Cat · Dec 15, 2017

Maybe you have a restriction in one of those burnt hoses.

al m · Dec 15, 2017

D2Cat said:
Maybe you have a restriction in one of those burnt hoses.

I replaced every hose,I just started anouther thread on valve hook up.I'm a little confused,one side of me says,it all works,as supported by Wolfman here,and my dealer,but my hydraulic understanding tells me I've got the valve plumbed wrong. Honestly,I'm a bit embarrassed,I manage a hydraulic shop,this should not be fooling me.
That said
Just realized
I'm going with my gut,will swap the lines tomorrow,I've stewed too long(truth is,daylight has not allowed me to do much)

al m · Dec 16, 2017

Back at it this morning,in the daylight,and with the snow and ice removed,I realize I had plumbed it all correctly in the first place,as Wolman stated,it must have been,because it worked .
Why the ruptured filter? I'm banking on a frozen relief valve due to moisture,only thing that is logical.
Thanks for the support,

ItBmine · Dec 17, 2017

torch said:
Wait, what?

You can lift the 3 point and the FEL simultaneously? That doesn't sound right, AFAIK, Power Beyond cuts flow to the 3PH when the FEL lever is moved out of neutral.

I can lift my loader and 3 point at the same time on my B. I went and tried it after I read this.

OrangeColoredTractor · Dec 17, 2017

al m said:
Back at it this morning,in the daylight,and with the snow and ice removed,I realize I had plumbed it all correctly in the first place,as Wolman stated,it must have been,because it worked .
Why the ruptured filter? I'm banking on a frozen relief valve due to moisture,only thing that is logical.
Thanks for the support,

You mentioned it was cold. Is there an oil bypass in the filter itself? This is common and the idea behind it is when oil is cold, it wont pass through the hydraulic oil filter fast enough, so it forces the bypass open (oil filter bypass, different that oil system relief) and if the filter didn't have the bypass or if it did, but wasn't working, the pressure can easily pop off the filter in cold weather. I think this may be the scenario. Do you still have the old filter? Cut it open, you will see the bypass valve, its on the center at the top of the filter, opposite of the threaded. And this valve is different then the typical bleed down check too, which is usually a rubber flap over the ring of holes (this si where oil passes into the filter) and comes out int he center hole). Depending on how they set, a bleed down check may not be used.

rjcorazza · Dec 18, 2017

Since routing problems seem to be off the table, I will add my experience.
Filters (oem) are capable of bursting from defects, or marginal specification. I blew a Kubota hydraulic filter years ago on my previous L3410 in cold weather. I believe it was between -10 and zero f , which is unseasonably cold for my area. Turns out Kubota had a TSB out at that time for areas one state north of me, and it specified an updated filter.
After that winter I started using synthetic fluid, and preheating the sump (somewhat) with 2 magnetic heaters.

Cobraone · Feb 12, 2018

Operation manual says to let the tractor run 10/15 minutes to let the hydraulic oil to warm up on my B2650.
Sounds like your hydraulic fluid might have been too cold for the pressure relief valve to function properly
Years ago we blew up a oil filter on a sand rail the same way, oil was too cold and pressure can build quickly.

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Omg,what went wrong,filter ruptured

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