Cheers Bundy on doing a service check on a David brown selectimatic hydraulic rear lift valve. I purchased a 880 a few years ago, and had to to do a full strip down of the valve body but couldn’t test it as I didn’t have your expertise on you tube, now I do thanks Bundy. PS once I serviced the valve it worked and still does plus I gave the lift cylinder a good clean.
Bang on Bundy, not only do they get forgotten about in the back of the shed as they are no longer front line machines, but funnily enough they are still called on as this good oldie has never let me down and she’ll be right. I had to split the tractor and put a new section on casting between the clutch and rear diff as the section of casting under the gear box had split. When I opened her up she was a mess! And I’m no trained tractor mechanic. Now she runs like a dream starts every time esp after I serviced the injector pump.
I’ve also built a wood splitter tandem trailer unit for my wood spliter and I’ve got a David a brown 880 engine running a tandem cat hydraulic pump runs like a dream once again I had to put a Sparex service kit into it and with your guidance via You Tube was awesome! Thanks.
Now that I've had my 990 back together, I've tested it out and all is wonderful. My issues were failure to hold and a "hiccup" when the arms were holding an implement up. Replacing the seals in the hydraulic cylinder helped a bit last year. When I had my valve chest apart, the only dirt I could really find was in the Hold Relief Valve. Cleaned it up (as you've seen on my channel), honed the hydraulic cylinder and replaced the hydraulic cylinder seals again. This thing is SOOOOO MUCH more powerful! It's amazing. The arms actually hold an implement up when the tractor is off. The arms with no weight on them will eventually leak down over a couple of weeks now. They were leaking down pretty much immediately when the tractor was off. Soooo happy with my 990 now. Great video on testing the valve chest!
This old valve is testing me. O ring missing under the hold valve seat, spool leaking but I'm testing different settings there, and surge relief leaks then it won't, I think I'll lap it in. Been all week after work on it. It won't beat me though.
G Day Lance, brilliant video, loads of info and help for people like us who are trying to restore old DB's and do most of the work ourselves, I've got an old manifold block from the spare axel I have I'm going to adapt it and try the same tests, save a lot of guess work, My 3D printer finally arrived got it built tonight hopefully be printing those little setting tools tomorrow. many thanks Barry
Looking forward to seeing the 3d tools. This bench test has certainly saved me from fitting a leaky valve in my case. I think the spool marking on mine may be wrong. Im yet to prove it so stay tuned.
I didnt want to rush you lance but ive been hanging on the edge of my tractor seat for these videos! So hard to find accurate diagnosis information on the db hydraulic system. A very advanced system for its time. And when its good its great but when its not its a shocker!! Look forward to the follow up vids😁
@@BundyBearsShed Absolutely agree with you there. They dont seem to keep the water out very well. Even after doing gear lever boots and sealing up the steering column mine still get a bit of water in. Ive got an implematic 950 and a selectamatic 880. Both the same!
I've restored an 880 and 990 and had bother with these units on both tractors. Mainly sticking valves which i could not free up. I saw someone recently using a rawl bolt to pull out the valves and thought this was a brilliant solution. On both occasions I sent mine to a UK company (Barclay Williams) who provided overhauled units for £500 (took a chunk out my profits) I'm looking forward to the next video to see how its done as I've heard of a DB that might be coming up for sale at a good price Keep up the good work Lance
Really interesting Lance. Looking forward to seeing it go back together. Fixing the hydraulics on my 880 was one of the first jobs I tackled. They would leak down and had a slight hiccup. When I took it out the date stamp showed that the valve was newer than the tractor so had been replaced at some point. As I’m just down the road from Barclay Williams I took it over and had it tested. Was leaking from the spool valve. To cut a long story short I exchanged mine for a refurbished valve. That and new piston seals and she’s all good again. Wish I’d had your setting tool though - didn’t do the Group 1 adjustments but everything works including TCU.
