428C struggling to lift front boom

[heymccall]

16 & 23 are both resolvers.

 

[Vetech63]

#23 was my issue on a previous machine doing the same thing. Orings blew out.

 

[heymccall]

There's a revision...also cross section pics to help visualize.

 

[heymccall]

And, nothing says that you have to update to the revised parts...you can just rering what's there.

 

[Pralhad Birdi]

Nige, could you please give me the part number of the valve in the picture, as I want to get the o rings from the dealer before removing the resolver. Thanks very much.

 

[Pralhad Birdi]

Heymccall, sorry just saw your post. That's brilliant, thank you very much.

 

[heymccall]

Heymccall, sorry just saw your post. That's brilliant, thank you very much.

The part numbers I posted are for the UPDATE, which has new resolvers and seals. If you're just resealing yours, you'll need different part numbers.

 

[Pralhad Birdi]

I do plan to reseal mine. Would it be possible for you to send over the part numbers?

Thanks

 

[Pralhad Birdi]

I do plan to reseal mine. Would it be possible for you to send over the part numbers?

Thanks

 

[Nige]

The part numbers I posted are for the UPDATE, which has new resolvers and seals. If you're just resealing yours, you'll need different part numbers.

It's somewhat weird. The Service Mag posted above by HMC is dated November 1999. The OP's machine was built in October 1997 yet searching under the complete Serial Number in SIS lists the updated parts........attached file.

However, and it's not clear in the Service Magazine article, out of all the Part Numbers ONLY the three hbackup rings (4T-7807, 126-5984, & 126-5985) are "new" inasmuch as before 1999 they were not used on the former 4T-4525 & 4T-4526 Shuttle Valve Assemblies. All the O-Ring Part Numbers, and the Ball, remain the same. I think if it was me I would remove one of the shuttle valves and check if it has backup rings installed on it. Then you know whether to order them or not.

 

[Pralhad Birdi]

Bit of an update:
Opened the resolver at the bottom of the valve, the o rings were okay, but the ball seemed stuck. Unstuck that, put it back. Then I opened the smaller one on the side (very accessibly located) and the half the o ring was missing. Replaced that, put it back, started the machine, but there was no difference.
Then I opened the bottom resolver for the bucket tilt valve, and the o rings in that were okay, but the ball was stuck as well. So I unstuck that and put it back. Tried to open the one on the side, but the allen head slipped. So I started the machine, and now when you operate the bucket tilt and boom lift together it lifts the boom, and when you operate the boom lift and bucket tilt together, it tilts the bucket.
So it's definitely better than it was, but I'm suspecting the second resolver on the bucket tilt. I'll have to remove the whole valve assembly to get access to that so it should be a fun job.
Anything else that I could try, or is the resolver the main suspect?

 

[Mobiltech]

If you’re finding the balls stuck I would think that means the ball seats are worn out and the ball will likely jamb again. I would recommend ordering the complete resolvers.

A tip on removing the Allen plug resolvers if you can get at them with a punch slightly smaller than the head of the plug give it a rap with a hammer and then try using the Allen wrench to take it out.

 

[Pralhad Birdi]

Thanks for the tip Mobiltech!
I've also ordered a hydraulic gauge test kit, because a couple of people have messed around with the pressures on this machine. The only problem is I've never really done any hydraulic pressure testing. What would the basic process be, and what sort of pressures would I be looking at?
I want to use this machine to gain some experience, then I hopefully won't have to rely on outside contract "mechanics" who don't really know what they're doing 90% of the time, which is quite a common problem in my neck of the woods unfortunately.

 

[Pralhad Birdi]

Extremely late update:
The culprits were the resolver o rings, all of them were gone on the upper resolvers of the front control, and all 14 on the backhoe controls were gone as well. Changed them out and it's back to normal now.
Would anyone be having the test and adjust specs for this machine?

Thanks

 

[Nige]

Would anyone be having the test and adjust specs for this machine?

Thanks

You mean for the hydraulic system..?

 

[Pralhad Birdi]

Yes for the hydraulic system.

 

[Nige]

Here you go.
Question for you back to the discussion on Page 1. When you pulled out the resolvers, did they have just O-Rings on them or did they have backup rings as well.?

 

[Pralhad Birdi]

Thanks very much Nige!
They had just the o rings. Well what was left of them anyway. No back up rings.

 

[Nige]

Did you install the backup rings..? I think I would have.

 

[Pralhad Birdi]

I didn't, but now that you mention it, I probably should. Will do.