How to replace seal on bucket tilt cylinder - bobcat 743

[MalcolmV8]

Hey Guys,

My work got cut short this morning but a small stream of oil spraying out and almost onto me. It's coming from the end of the bucket tilt cylinder. Almost looks like the seal on the end blew out in a tiny spot. Can I replace this at home? I'm technically inclined and work on engines etc. I just don't know anything about these hydraulic setups or if any special tools are needed? Pics below.

Thanks for any insight
Malcolm

 

[MalcolmV8]

I watched this video and it looks to be the exact process I need to do even though he was on a lift cylinder.



I was also searching on this forum and found an old thread where a guy said once he had the gland nut off to remove the cylinder instead of cracking the oil lines he just bumped the motor over with the starter and let it gently push it out.

Overall it looks like I have everything I need except the gland nut tool. So I'll get a tool and seals ordered and hopefully back in business soon

 

[MalcolmV8]

I'm over at https://partscatalog.bobcat.com/ and based on my serial # there are 4 different tilt cylinders and each one takes a different seal kit and it doesn't explain the differences.
They have a tilt cylinder (cessna), tilt cylinder (bobcat), tilt cylinder (bobcat) (w/replaceable tubes), and just plain tilt cylinder. Hmm.

 

[MalcolmV8]

Took a bunch of measurements and figured out I have the "tilt cylinder (bobcat)". So I got a gland nut tool and seals on order. Hopefully fixed this Friday when everything comes in

 

[Rockin Ranger Rider]

Took a bunch of measurements and figured out I have the "tilt cylinder (bobcat)". So I got a gland nut tool and seals on order. Hopefully fixed this Friday when everything comes in

Hey Malcolm, just a thought for you, I have an older Daewoo DSL 601 and have done my bucket cylinders twice each. The first time lasted over 10 years with light use. The second time was done 6 months apart but I buffed the piston and inner cylinder on this go around. I used the long flex shaft drill mounted for the cylinder and a 8” cotton wheel on a bench grinder. I used white diamond as the dressing media. They felt real good afterwards with just a slight bit of pitting noticeably on the cylinder walls. It’s great to fire it up and everything remains dry. One thought about your gland nut , I just used a large plumbers ridgid pipe wrench and a large Wilton vice. My arm cylinders are starting to clamor for attention! Alan in Winslow

 

[laurencen]

I changed our seals a few tears ago, you can do this without removing the cylinder just remove the gross pivot pin and rod end, if you are going this far my suggestion is also replace piston seals, also check the cylinder rod is not bent, I have straightened a few and seem to bend when the tilt is fully down and the bucket is pushed for grading or spreading material, this will cause the front seals to wear our prematurely.

good luck its not that big of a job just have a pail to catch the oil that runs out when the piston is pulled

 

[MalcolmV8]

I got cylinder out and apart and my analysis of which cylinder I have was apparently wrong so I still need to figure that out.


The big surprise for me was this massive nut on the end. Turned out to be a 1-11/6" nut. Has to be a super thin wall too which I couldn't find so I had to grind a socket down to fit in there. Big Milwaukee impact to back that sucker off.



Here's the shaft pulled apart mostly.



Here's some pics of the parts and their sizes. Maybe someone can help me identify which tilt cylinder I have?

A few of the piston itself







The gland nut





Has the number 78 stamped on top with a circle on it.

 

[MalcolmV8]

First post wouldn't let me post more pics. Continuing.



Shaft and parts



Piston is 3.250" in diameter



The shaft is 1.5"



Gland nut is 3.740"



The eyelets for turning off the gland nut are 2.850" apart center to center



The nut is 1.665"

This is the seals off the piston



These are the seals off the gland nut



Hopefully someone recognizes this and knows what cylinder I have?

Thanks
Malcolm

 

[stevelil]

Hello Malcolm, great job on the disassembly and cleaning prep on the cylinder.
Try calling Hercules Hydraulics 1-800-777-5617. they can help you.
here are the three possible kits you need for the 743 2.25" bore, 1.5" rod

https://herculesus.com/product.php?pd=Y&cat=18579&pid=776970&productcode=BCK-6514736https://herculesus.com/product.php?pd=Y&cat=18579&pid=776971&productcode=BCK-6804605https://herculesus.com/product.php?pd=Y&cat=18579&pid=776972&productcode=BCK-6661297
look at the images and details of each kit and compare them to the seal that you removed from your cylinder.
I hope this helps
Steve L
New Jersey

 

[MalcolmV8]

Thanks Steve, I appreciate the link and reference. I actually spent a lot of time last night looking at pictures on bobcat's parts catalog website counting seals, and comparing any little dimension reference they have like how far the hydraulic hoses connect from the end of the barrel etc. Looking at the piston shape, the number of seals on it etc.
Previously I ordered seal kit: 6661297 based on what I could see on the outside. However after disassembling my cylinder and having much more detail I've ordered seal kit: 7135551 which will be here tomorrow. If that's not it I'll give Hercules Hydraulics a call and see if they can help me identify it.

I'll let you know
Thanks
Malcolm

 

[MalcolmV8]

Well I can confirm the correct seal kit is 7135551. Hopefully this helps someone else searching in the future. I got the cylinder all put back together and ran some quick tests this evening and it's looking great.

I thought the hardest part, from watching youtube videos, was going to be stretching out and getting the piston seal on but it was a breeze. The hard part was getting that fat inner seal into the gland nut. I spent 5 minutes monkeying with that thing till I got the hang of it and got it in there.

Immediately something I noticed was how much better the operation is. Like when I tilt the bucket all the way up it doesn't bounce at the top anymore. It was minimal but noticeable and now it's smooth and solid. I also noticed if I don't fully tilt the bucket down to release all tension when shutting it off it would creak creak creak annoyingly loud as it was slowly lowering itself. Now it just holds solid and dead silent. So overall pretty happy. I should be able to give it a full on days work test tomorrow or the next day depending on the rain.

Thanks
Malcolm

 

[FJRDarksider]

Good job on the repair!
I found a full tilt cylinder seal kit for my 853 on Amazon of all places ($20). Have over 60 hours on it and still going strong.

 

[MalcolmV8]

Yeah I found my seal kit on Amazon too. No one else can get you the kit next day or 2 day and have you back on the job that fast.