Repair-It

Hydraulics slow down as machine gets warmer. First suspect was the return hydraulic filter as I've read those can cause these symptoms. Swapped in the "original" filter to see if it improved - it also may be partially restricted. Seemed to be better, but not fixed... Ordered a new filter.

I'm suspicious the pump wear parts may be tired. Looks like a pump overhaul "kit" may be necessary - about $200ish I guess. One guy I've ordered decent stuff from in India, Ray at All Backhoe Parts on eBay has been great. I messaged him this morning and he showed seal kit (PN 920/01647), but he was out of the wear plate kit - 920/01804. I really want kit 920/01646, but the only listing I see on eBay is $2100...

I really wish the JCB dealer was much easier to talk to - the Berlin CT store is horrible to try to get the parts guy on the phone.

I ordered a hydraulic pump seal kit, wear plate, and bushings from eBay/Amazon. About $350 total. Hopefully the part quality is OK - I couldn't even get JCB to provide a price, and at least wear plates are not available until November.

https://www.ebay.com/itm/164610845228
https://www.ebay.com/itm/162439453667
https://www.amazon.com/gp/product/B0C5V ... UTF8&psc=1

I can't quite tell, but these guys may be the new OEM for Hamworthy/David Brown that was the JCB pump supplier. They seem to cross reference the 920/01646 kit PN, but I think I might need two of those kits based on the picture. 364 pounds sterling, so >$400. At least maybe they're a fall back if the stuff from Amazon looks crappy.

https://www.whitehouseproductsltd.com/p ... =true#jump

Whole pump assembly that might be the right one. PN doesn't quite match, but it looks like it's from a similar SN machine, so might work OK.

https://unwinhydraulic.com/products/919 ... 4800&_ss=r

Sheet 367 and 373/374 cover pump removal and disassembly (per Ray I have the David Brown/Hamworthy type).

https://drive.google.com/file/d/1nE4QBg ... drive_link

Sheet 263 gets into some theory of why there's an electric one-pump unloading function on the machine - to provide more available hp for road use. As far as I know the unloader circuit hasn't worked since I've owned it - I've tried flipping it a couple times and never noticed anything different. I may need to get it functioning again if the pump rebuild is successful and the pump load packs a lot of additional hp drain/punch after.

Pulled the pump off this weekend. It was easier than I thought it would be. Dealing with the 20+ gallons of hydraulic oil was almost a bigger pain than removing the pump. It is heavy (60+ lbs?). Had to hang a strap through the engine lifting eye and around a hand rail to let me slowly lower it to the ground.

Pulled the pump apart. No real smoking gun, but there are some wear marks on the wear plates and the seals seem tired. Hopefully it'll be better with new plates. The service manual talked about different-size-oil-seal units on early ones and later ones with two-same-size seals. I have the two-different-size seals, and the kit only came with two same-size-seals. I ordered the right seals for the staggered size one from Zoro (SKF brand). Hopefully they come in soon. I guess the original ones were Viton and I can only find Nitrile (slightly lower temp rating, 210F max-ish). Should be OK. it's also SKF's "fancier" CRWA1 seals vs. their regular CRW seals, so they're supposed to have less drag and run cooler. The only "reason" to pick Nitrile over Viton would be low-temp-flexibility, which I don't think was an issue for this application, so I would've preferred Viton.

Using my Breeze wifi....

HF also has Viton: https://www.harborfreight.com/180-piece ... 67525.html And whatever HNBR is: https://www.harborfreight.com/205-piece ... 67644.html Oddly to me the HNBR is green not Viton.

Not o-rings - oil seals. 11225 / 11133 SKF (old one that had a number was a CR-11207)