Fixing thread for hydrolic filter B7000

dakarbemo

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Kubota ZB7000, 120cm wide coroni mower, trailer
Feb 7, 2010
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Hi everyone,

I am in the middle of doing the first full service on my Kubota B7000. Previously it was done by a mechanic but all the hassle with transport and the easy of doing it myself lead me down to just do it myself. Replaced engine oil, coolant and the gearoil in the front diff/gearcases. Now i drained the gearbox and I thought, lets check the hydrolic filter. I unscrewed it and inspected it and tried to screw it back in place.

It wouldnt screw in very well, and looked to be at a slight angle to I backed out and welll either I or the previous filter-inspector damaged the threads in the frame/gearbox. I believe what I can see that it is only a few turns that are looking a little deformed. In other words I have to fix this. I think you can just retap on the existing tread wich "fixes" the small area wich is damaged? Or do I really need to let a mechanic take over. Also gotta figure out wich thread it uses, I am not the most experienced mechanic but not clueless either. Just dont want to ruin the entire gearbox housing.....cant really find replacements laying around. AKA any input is helpful. Thanks!
 

Roadworthy

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This might be a really good time to let the mechanic take the job. That way the shop is financially responsible if they bugger the threads. Of course if the threads are already ruined it's between you and the prior mechanic.
 
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Tughill Tom

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1st thing is determine the thread pitch with thread gauges and then you can think about chasing the existing threads if not too far gone with the correct size tap or thread file.
 
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dakarbemo

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get a thread restorer file. Use that to clean up the threads. Here is a video of it being used.
Unfortunatly I dont think this works as the bolt which is part of the filter is in good shape. Its the threads in the frame that seem to be damaged
 

TheOldHokie

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Unfortunatly I dont think this works as the bolt which is part of the filter is in good shape. Its the threads in the frame that seem to be damaged
If the threads are damaged to the point they cannot he salvaged a thread repair insert can be installed. That involves drilling the old threads out and re-tapping the hole for the insert. I would expect thats a relatively large diameter and probably best left to a professional with the proper tools and experience. I would not expect it to be hugely expensive. Getting the tractor to the shop is probably going to cost as much as the actual repair.

Edit- BTW filters are usually female thread. If yours has a male thread the male adapter that is normally screwed into the housing may have come off with the filter.

Dan
 

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dakarbemo

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Kubota ZB7000, 120cm wide coroni mower, trailer
Feb 7, 2010
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If the threads are damaged to the point they cannot he salvaged a thread repair insert can be installed. That involves drilling the old threads out and re-tapping the hole for the insert. I would expect thats a relatively large diameter and probably best left to a professional with the proper tools and experience. I would not expect it to be hugely expensive. Getting the tractor to the shop is probably going to cost as much as the actual repair.

Edit- BTW filters are usually female thread. If yours has a male thread the male adapter that is normally screwed into the housing may have come off with the filter.

Dan
Thanks for your input Dan! At the moment I am trying to figure out the thread that is on the filter. It's an older tractor so doesnt have the fancy modern hydrolic filter, it has a mesh filter which goes to the returnline banjo and then screws into the frame. The thread is pretty long/deep but only a few turns look to be damaged. Hella akward spot, which doesnt make it easier to work on ;)

But for my personal challenge currently trying to figure out which thread is used. Only one partsdealer provides the thread as being 3/4"-14 UNF. But looking around makes it seem like this thread is quite rare. But all in all, I am thinking this stupid small job is going to a mini-digger dealer with pickup service. Not my ideal way to spend my christmas budget. I think those guys should be perfectly able to handle the job, hopefully they will take it
 

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TheOldHokie

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Thanks for your input Dan! At the moment I am trying to figure out the thread that is on the filter. It's an older tractor so doesnt have the fancy modern hydrolic filter, it has a mesh filter which goes to the returnline banjo and then screws into the frame. The thread is pretty long/deep but only a few turns look to be damaged. Hella akward spot, which doesnt make it easier to work on ;)

But for my personal challenge currently trying to figure out which thread is used. Only one partsdealer provides the thread as being 3/4"-14 UNF. But looking around makes it seem like this thread is quite rare. But all in all, I am thinking this stupid small job is going to a mini-digger dealer with pickup service. Not my ideal way to spend my christmas budget. I think those guys should be perfectly able to handle the job, hopefully they will take it
OK - that makes more sense. That suction line strainer was used on a lot of models including my B7200. Given the vinatge of the tractor I am guessing BSPP. Those threads don't look horrible and you may be able to simply clean them up with a tap. If you have a caliper measure the OD of the threads on that strainer - may be able to ID it from that - 3/4 BSPP would be 1.041 and 1" BSPP would be 1.309. I have had that out a few times and I don't think its any larger than that.

Dan
 
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kubotasam

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Have you tried threading the strainer in with the banjo fitting out of the way? I have had problems getting the strainer in straight going through the fitting. If you can get the strainer started straight without the fitting maybe it would correct the damaged threads.
 
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dakarbemo

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Feb 7, 2010
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Have you tried threading the strainer in with the banjo fitting out of the way? I have had problems getting the strainer in straight going through the fitting. If you can get the strainer started straight without the fitting maybe it would correct the damaged threads.
That is likely why the treads are damaged, going in at a tiny bit of an angle. I tried fitting it without the banjo but I am too affraid of ruining even more threads by trying to screw it into place with a bit of force. My first service turned into a bit of a nightmare. I think i'll give up and send it to a shop which sells & repairs mini excavators. Just praying it wont end up costing 500+ Oh the joys of owning stuff like this
 

dakarbemo

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OK - that makes more sense. That suction line strainer was used on a lot of models including my B7200. Given the vinatge of the tractor I am guessing BSPP. Those threads don't look horrible and you may be able to simply clean them up with a tap. If you have a caliper measure the OD of the threads on that strainer - may be able to ID it from that - 3/4 BSPP would be 1.041 and 1" BSPP would be 1.309. I have had that out a few times and I don't think its any larger than that.

Dan
Yeah measuring the outside diameter the sizes fit the BSPP 3/4 - 14 thread. I looked at getting a tap but the only ones I could find ware over 150. To spend 150 with the added risk of me making an even bigger mess doesnt appeal to me right now haha
 

TheOldHokie

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Yeah measuring the outside diameter the sizes fit the BSPP 3/4 - 14 thread. I looked at getting a tap but the only ones I could find ware over 150. To spend 150 with the added risk of me making an even bigger mess doesnt appeal to me right now haha
Probably the case and Mcmaster has the tap for $50. I would verify 14 TPI before going in.

Risk is hard to price.

If thats all thats needed the cleanup repair wont cost anything close to $500. Hauling is a separate issue.

Dan
 

Captain13

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If you want to verify the threads, go to a NAPA store. They can look up their filter for your tractor. Then there is an info section on their parts that will give you the thread size.

Their system has a Kubota parts section So it’s easy for them to look up.
 

Lil Foot

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I'm kinda surprised that thread is an SAE size. Everything I know of on my B7100 is metric, except for the spin on engine oil filter thread. Just sayin....
 

whitetiger

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If you want to verify the threads, go to a NAPA store. They can look up their filter for your tractor. Then there is an info section on their parts that will give you the thread size.

Their system has a Kubota parts section So it’s easy for them to look up.
I doubt that there is a NAPA store in his neighborhood. I am fairly sure they do not have a presence in Holland. :)
 
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dakarbemo

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I'm kinda surprised that thread is an SAE size. Everything I know of on my B7100 is metric, except for the spin on engine oil filter thread. Just sayin....
It's a pain hahah the thread is either BSPP 3/4 - 14 or UNF 3/4 -14, but the last one is mentioned on one of the replacement parts website as being the thread. But that tread is quite rare and I cant find the nominal diameter of it, the "normal" one would be a UNF 3/4 - 16. Taps that size are also rare around here. It's my personal challenge to find out what thread it is now, gone too deep into the rabithole to let this one go :).
 

Chanceywd

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I might be out in left field on this but isn't 3/4 npt 3/4-14? If it is and the same od would you be able to chase the thread carefully with a pipe tap? the taper might actually make it easier to start straight. I am working from memory here and was thinking 3/4 pipe is about an inch and an eight od.

Bill

OK a little reading https://www.valvesonline.com.au/references/threads/ and I see the difference in my suggestion that there is a angle of 55 deg and 60 deg on the thread and flat and curved on the bottoms.
 
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dakarbemo

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I doubt that there is a NAPA store in his neighborhood. I am fairly sure they do not have a presence in Holland. :)
True haha not one around, I also doubt Nappa would have truely accurate info on these tractors as even B7000 manuals do not exist really. I've got the closest one which is one for B5100/5001, B6100/6001, B7100/7001, in this workshop manual it also doesnt refer to the threads of the filter at all
 

TheOldHokie

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It's a pain hahah the thread is either BSPP 3/4 - 14 or UNF 3/4 -14, but the last one is mentioned on one of the replacement parts website as being the thread. But that tread is quite rare and I cant find the nominal diameter of it, the "normal" one would be a UNF 3/4 - 16. Taps that size are also rare around here. It's my personal challenge to find out what thread it is now, gone too deep into the rabithole to let this one go :).
The major diameter of a 3/4-16 UNF thread is .750. Not even close to 3/4 BSPP at 1.039. It is also a straight thread not a taper pipe thread of any form. If that thread measures 1.031 and is 14 TPI it is almost surely BSPP. If in doubt take it to a hydraulic shop and have them ID it.

Dan
 
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GeoHorn

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Whenever THIS backyard-mechanic runs into problems like this…. I consult my friend who is a genuine machinist…. If he doesn’t have the tool needed…. he MAKES one…. and things always goes better after that.
 
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