BX23 new HST blowing filters

csim

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Equipment
BX23
Dec 31, 2015
13
0
0
arlington, ma
Hi Folks,

Hoping you can point me in the right direction...I just replaced the HST on my BX23 with a brand new one and got everything back together. Just in cranking over the engine to test it, I've now blown two hydraulic filters (metal of the filters blown backwards with foamy hydraulic oil shooting).

I'm hoping you can give me some tips on how to troubleshoot this hydraulic pressure problem to find the cause.

Thank you very much!
 

RCW

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Equipment
BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
Apr 28, 2013
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Chenango County, NY
You replaced the HST filter?

It leaks fluid when starting?

I think there might be the old rubber gasket from the last filter, or you cross-threaded the new filter.

Or, did you replace the entire HST?
 

csim

New member

Equipment
BX23
Dec 31, 2015
13
0
0
arlington, ma
I replaced the entire HST (removed transaxle/etc). My BX23 had about 2400 hours on it and the HST died. I feel very sure that there was no issue with the two filters that blew (and no extra gasket on the mating surface). Thanks for your help/thoughts...not sure how to best find the source of the problem.
 

csim

New member

Equipment
BX23
Dec 31, 2015
13
0
0
arlington, ma
I should also point out that the filters are blowing just with cranking over the engine with the starter, not with the actual diesel engine running. So, very low RPM of the HST and the hydraulic filters are blowing out. Thank you.
 

D2Cat

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L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
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csim, I'm not familiar with your machine, but if you have hyd. filters coming unglued you have TOO much pressure being caused by something you did/or didn't do.

Is piping hooked up correctly? Did you install the correct part? Fluid level correct?
 

RCW

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BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
Apr 28, 2013
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Chenango County, NY
csim - -

My apologies, I didn't get the extent of the repair.

Wow - like D2Cat said, something is amiss.

My sincere apologies, too, in that I haven't a clue. It seems the low pressure side of the HST includes the filters, and somehow they're plumbed to a the high pressure side?? Or do I have that that backwards??

Just reaching...man, I wish I had a better idea for you....

Best wishes, and good luck!!!:)
 

RyeThomas

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Dec 23, 2015
56
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Northern Virginia
While I have no experience with your machine exactly I do have some experience with High Pressure Common Rail Fuel injection, so bear with me I am trying to help.
Don't get caught up with the fact it's blowing while cranking, I can understand your concern but realize todays pumps make high pressure at low to no rpm to begin with. A CR injector pump can make over 26k-psi before a relief valve kicks in but the system needs 6-8k min just cranking to start and they make that even when cranking slow with a tired battery. I'm sure these hst's make considerable pressure while cranking.
So either the pressure has no where to go i.e. Blockage or fluid return is blocked, or your pressure relief valve (if you have one is being exceeded and is not opening), again I'm not certain on the hst here.
It's finding the weak link which is the aluminum filter, over pressurizing and blowing out.
I wish I could be of more help but I would seriously run through everything, blow out any lines, check and recheck before attempting again. You could cause some serious damage sooner than later.
Best of luck, Rye.
 

North Idaho Wolfman

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Jun 9, 2013
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You have a blockage, it's most likely in the relief valve, sounds like it's stopping all flow. ;)

Pull the relief valve and try it again.
 
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100 td

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B21TLB (B21, TL421 & BT751) Toyota SDK4 T116 Bobcat
Aug 29, 2015
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ɹǝpunuʍop
First thoughts, may not be the case but worth a check anyway. If your engine comes with a "permanent magnet" starter motor, and when you split the tractor you disconnected or changed the battery, you then accidentally hooked the battery up in reverse and you are now cranking the engine over backwards and pumping oil backwards and blowing the non return valves out of the filters.
 

csim

New member

Equipment
BX23
Dec 31, 2015
13
0
0
arlington, ma
Thank you all for your thoughts. The piping is rigid so nearly impossible to reconnect wrong. Fortunately, the battery is upfront near engine so I never had to disconnect (although it probably would have been good for me to.

I'm definitely on board with a blockage. On this HST, has anyone pulled the relief valves before? Are they on the sides of the HST or the top, other? They seem so inaccessible to me on the sides.

Thanks all!!
 

Tooljunkie

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L1501,home built carry all, mini plow blade.
May 13, 2014
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Any chance a plug was installed in factory to keep dirt out and it wasnt removed prior to installing? Its a shot in the dark.
Perhaps the hydrostatic unit is faulty.
 

csim

New member

Equipment
BX23
Dec 31, 2015
13
0
0
arlington, ma
Update: I called the Kubota dealer from whom I purchased the HST and they said there's an internal plug which needs to be removed prior to installation. Unfortunately, no notification of this in the parts box. I have to rip the entire tractor apart again, but at least I have a good lead on the problem and their service department is very helpful. Keep you posted, thank you all for your thoughts.
 

100 td

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B21TLB (B21, TL421 & BT751) Toyota SDK4 T116 Bobcat
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Well that's good news of sorts! Hopefully it will be all sorted soon, any chance of the dealer coming good with a couple of filters?
20 years ago I flew out to a mine and was given an airconditioner to fix on a large face shovel they were having trouble with, no aircon means no operator, and of course this holds up 6 trucks as well. I found someone had replaced the evaporator and left the bungs in the end fittings, no wonder there was no refrigerant flow!
 

Tooljunkie

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L1501,home built carry all, mini plow blade.
May 13, 2014
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Lac Du Bonnet, Manitoba,Canada
Thats where i learned about a situation like this .guy put an ac component on my car and left plugs in lines. Caused me a lot of grief.
 

ThisIsNotaStep

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2005 bx23 tlb
Nov 26, 2010
133
1
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Ontario, Canada
Looking back any tell-tail signs the pump was about to go? I have a BX 23 too, got her used with app 500 hrs on it .. never sure what it should sound like but indestructible so far .. when it's all said and done what would you have into the whole repair?
 

csim

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Equipment
BX23
Dec 31, 2015
13
0
0
arlington, ma
Hi Folks, definitely a bummer they didn't tell me about the hidden plugs. Thanks for all of the great feedback including pics.

You will definitely know it when the HST starts to go...you'll hear/feel a grinding noise when you try to drive forward/backwards with even a light load. They say these things rarely go...I drew the lucky straw, but also have advanced hours on it at ~2,300. I'd say just about $2,000 into it for this repair.
 

mpaton

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Equipment
Kubota BX23/BX23D
May 16, 2022
3
1
3
Texas
Can anyone who's replaced the HST on the BX23D say where these mysterious plugs are located?
Thanks
 

whitetiger

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Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
Nov 20, 2011
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Kansas City, KS
Can anyone who's replaced the HST on the BX23D say where these mysterious plugs are located?
Thanks
They are not a mystery or hidden, they are very much visible and out in the open.
There are 3 white or clear plastic plugs stuck into the oil passages on the rear of the hydrostat assembly.
 

mpaton

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Equipment
Kubota BX23/BX23D
May 16, 2022
3
1
3
Texas
They are not a mystery or hidden, they are very much visible and out in the open.
There are 3 white or clear plastic plugs stuck into the oil passages on the rear of the hydrostat assembly.
Thanks for the location, and I see them now. I had thought a previous post said they were hidden under metal plugs, but I couldn't find that post.

Thanks for the help.
 
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