B7100HST banjo fitting leak

[EdF]

I had to install a heli-coil after stripping threads on the HST case at a banjo pipe joint (see photo). Now I am having problems getting the copper washer between the pipe and the HST to seal. I used new copper washers on the joint. I cannot find a torque spec for the connection and maybe that is why the joint is leaking. I do not want to strip the HST case threads again so I'm wondering if there is a better washer available that can be used to seal this joint? Suggestions or comments would be most appreciated to help me out of this mess.

 

[dmanlyr]

Banjo fittings have to be fairly tight to get the proper crush on the sealing washers. The heli coil if installed correctly will take as much, if not more than the factory threads. Not sure that I have ever noted a torque spec for these, at least on tractors.

That said, are you sure that the heli coil was installed square with the housing? Even the slightest crookedness will cause a unfixable leak in this area, as the metal sealing washers are not capable of crushing enough to fill a abnormal gap on one side, did you use a square to align the tap?

Depending upon the pressure (or vacuum if on the suction side) involved, you may have to tap the case for a NPT and run a rubber hydraulic line to eliminate the factory metal pipe and banjo fitting. Problem with this approach is a NPT and hydraulic hose / fillings is going to take a lot more space.

David

 

[Stubbyie]

I've had some luck using a quality room temp vulcanizing (RTV) material aka silicone sealant in similar cases.

Disassemble, clean EVERY component scrupulously clean with acetone or similar and let dry thoroughly, go back with new copper washer, apply RTV deliberately and located so as to not inadvertently plug any port(s) when squeezed or compressed, assemble, make up ALMOST tight, let cure 24-hrs, then tighten as you desire taking into account the helicoil as you think best.

Please report back your experiences so we may all learn.

 

[EdF]

David,

Thanks much for your input. The heli coil was installed using a jig rigged by a machinist so I believe it was squared with the housing. I am going to put more torque on the bolt in hopes that it will seal. If not, I'll try another type of sealing washer (fiber?) or a larger copper washer. If that fails I'll go for the NPT fitting and hose. This B7100HST is a great tractor with only 350 hrs of babied use. It's so pristene my machinist asked how long it took me to restore it.......that made my day.

Stubbyie,

Also appreciate your input and will give it a go if needed. I will report back on how things go, however that may take a few weeks as I am in the middle of a remodel project and just no time to get to the Kubota right now.

 

[North Idaho Wolfman]

No one asked so I guess I will, What thread was the heli-coil?

Also install 2 copper washers instead of one to get it to seal.

 

[ShaunRH]

If you can find one that fits, spark plug style compressable washers can be used too. Copper takes more force to compress down. Another option might be to oversize the internal hole of the washer to fit a Viton O-Ring between the bolt and the washer. Normally that's a quick field repair but it might last longer if you did it right and gently enough...

Most guys are switching to rubber clad/bonded washers for troublesome fittings like this but again, torque is a problem with these bolts so more is not always better!

You can try aluminum washers as well.

 

[EdF]

NIW,

It was a 3/8" British Standard Pipe thread 19 tpi.........not very common here in the USA. Thanks for the 2 copper washers idea.

ShaunRH,

Thanks to you also for the ideas.

 

[Rftlts]

BSP Is very common for hydraulic fittings.

 

[EdF]

Finally had time to tackle the banjo joint leak this afternoon. Much to my joy I was able to stop the leak simply by putting more torque on the bolt. Fortunately, I did not have to resort to many of the suggestions you all offered to fix the leak. Regardless, I want to thank all for the suggestions/comments to help resolve the problem.

 

[North Idaho Wolfman]

Excellent to hear!