Backhoe BT751 (b21) dipper cylinder leak at idle

[joea99]

Reinstalled BH after playtime with box scraper was over.

Found some oil spots on the ground after I parked for the day. Seems the dipper stick cylinder is seeping pretty good, even at engine idle and all valves in "neutral".

I'd have though there should be zero pressure under those conditions?

It's seeping enough I don't really want to use the machine right now. Not only makes a mess, but, I fear it might pop completely and leave me drenched as well as stuck.

 

[joea99]

OK, so anyway,

I've decided to tackle the seal job myself. Done a couple before and cussin and moanin got the job done. But this one seems a bit more challenging. Since all the BH dust seals are looking a bit the worse for wear, I will be doing them all before long, no doubt. So, need to figure a sure way to do the job.

The internal seal I can deal with, even if I guy the three prong tools that are all over the internet. But the piston seal, the one with the two in a single groove, looks a bit more challenging, due to the quite stiff nature of the actual seal.

The "jigs" the WSM specs out, no one seems to use, or even know how to get. "build on site" seems to be the drill. I'm attempting to make some with a 3D printer, (I have the CAD drawings made up), but some seem to feel plastic is not going to do the job, they need to be in steel. I'm getting some Carbon Fiber filament that is supposed to be much stronger and provide a smoother (and polish able) surface. I guess I'll find out.

There are some posts here that say Kubota shops just heat the seals in oil, then freeze and/or compress the seals (with piston ring compressors or padded hose clamps) and that does the job.