Fixing handle leaks on Hitachi's

[RobVG]

I usually don't fix stuff like this but I have time now.

I've done two EX's and one Zaxis. Here's a few pics of a Zaxis 120 I started on today. Thought you might like see what's in there. If anyone's interested, I have more pictures and can describe how to do it. If not, just enjoy the beautiful pictures ...

 

[willie59]

Done it myself RobVG, I've had to reseal a number of Hitachi EX joystick controls. It appears you do the same as I do when working in the cab of an excavator...get this $#&^ seat out of my way!

 

[RobVG]

Yup, take the levers and foot pedals off, raise the window and the seat comes out the front of the cab, along with 10 lbs. of garbage and site plans the opperator had stuffed down behind it.

I guess a lot of guys probably do this job on their own equipment?

Anyway ATCO, my memory must be getting really bad. I know I've done a Zaxis before but the kind of valve that's in this 120- I don't remember working on??? It just has a rubber seal at the top of the plunger block on the inside. The seat for the seal is machined into the block. Does that sound familiar?

I don't think the dealer sold me the right seals- I'll find out tomorrow.

 

[willie59]

Yeah, I think you've got it right. And, yes, I pretty much get the glass and seat garbage out of the way as well. It gets hard on the knees working inside an excavator cab, it helps to get the "junk" out of the way so you can do the work.

 

[John C.]

I've never had to pull any of that stuff to reseal those things. Basically the handle comes off, then the U joint and the plate comes up. I use a plastic lined pair of pliers to pull the pistons out. Swap the seals and push it all back together. Takes about an hour and a half per side.

I forgot about releasing the pressure in the accumulator and draining the air off the tank before I start taking them apart.

I wonder why Hitachi / Deere never fixed that problem. Almost every Hitachi over 5,000 hours has the leaky controllers.

 

[RobVG]

Hi John

We have five EX-5's and four Zaxis and you're right, they all start leaking around 5k.

Basically the handle comes off, then the U joint and the plate comes up.

Yeah but to get to that point you still have to get the valve out of the sheet metal---right? I think the only extra steps I took was removing the seat (4 allen bolts) and the levers/pedals (5 mins).

The EX-5 valve is a challenge. Once the u-joint is out, you have a spring loaded sandwich thats a pain to put back together after replacing the seals. The only thing I could come up with is to cable tie the anodized plate to the valve body so I could get the u-joint back in- then cut the cable ties and tighten up the u-joint.

With this latest valve in the picture- you don't remove the u-joint. The seals are much less expensive too.

 

[John C.]

As I recall all the EX machines just had the rubber boot and a plastic cover over the valve. When those were off I just sat in the seat and did my work.

Maybe they are completely different on the ZX machines?

 

[RobVG]

Ok the rubber boot and plastic cover- I'm with yah, but the valve I'm currently working on is bolted down through the sheet metal housing- into the valve. You have to drop the valve out of the housing to work on it.

And that's just the swing side. On the boom side you have to unbolt the housing from the seat mount and pull the whole thing away from the cab to be able to get to the valve.

Well, if my memory is correct (and it's not always) the other EX's and the other Zaxis were the same way- you couldn't get at the seals without unbolting the pilot valves and dropping them down. On the EX the top part of the housing pulled up and out of the way.

Maybe it's the size of the machines- these are 120's and 160's. Or maybe you're just way more creative than I am.:notworthy

 

[John C.]

You got me on that one Rob. I've never seen them mounted that way before. I've got a photo somewhere of what I worked on. I'll find it and post it.

As much as those things like to leak you would think they would have made something better by now.

 

[RobVG]

I'd like to see the pictures if you can find them.

My luck ran out tonight. I fired it up and ran the boom and curl for awhile and hydraulic started running out of the housing. I took the boot off and can see the seals riding up and down in their bores- they shouldn't be. I took off the boot on the swing side and started it up and move the stick and swing- it started puking from all four plungers, the seals are moving there too. Tomorrow I'm going to take it apart and see if these seals need to be driven in further somehow. I've had better days...

 

[willie59]

Hey Rob, I haven't done a Zaxis, I've done a couple of EX120-2, been a while though so memory is vague. I'm missing something here. I look at your pics, and all I see is spools and seals. What retains the seals in the valve body. It looks like you drop spring in hole, insert spool, then seal, I don't see anything else. Is that right?

 

[RobVG]

ATCO I haven't seen this setup before. On the older machines there has been brass bushings/sleeves which contain the seals.

...all I see is spools and seals. What retains the seals in the valve body.

The seals sit in the "block" (that's what they call it). There is a seat that's machined in the top of the block, you can see it in the pic above if you look down the bore.

It looks like you drop spring in hole, insert spool, then seal, I don't see anything else. Is that right?

You don't even touch the spools and springs- they stay in the valvle body (very top pic). All you do is remove the "block" and pull the plungers out and replace the seals.

I think they might need to be driven in with more force.

 

[willie59]

Yeah, I see it now. It's that plate that's held in place by two allen head screws in the first pic of post #8, shown mounted on valve body. That is different from the -2 machines that I have worked on. They use the brass seal retainer that you mentioned. I'm still trying to figure out how you can see the seals moving when operating the valve, there's something wrong with that.

 

[John C.]

I found the photo of the older style controller placement in the small machines. It is different though.

 

[dieselmax]

Hi Guys,
For your information the seals are a major on going issue with Hitachi!
Dash 2,3 and 5 all leak around 5000hrs but they are the brass insert types which have been modified and no longer leak.
The Zaxis is a different story, Hitachi don't supply individual seals any more you buy the complete aluminium head inclusive of seals and new pistions for the Zaxis machines. If any one is interested I can post the part numbers. You pretty much waste your time installing the individual seals as they continue to leak!

 

[RobVG]

NOT RESEALABLE

You have to buy a new "block" which comes loaded with seals. The good news is, it's only $68- still cheaper than the seals for an EX. Also it's easier to do than other Hitachi pilot seals.

Thanks for the Pic John.

Rob

 

[willie59]

Wow, that doesn't sound half bad!

I've done the ones with the brass insert. Yeah, they are a trick to do. I would press the pilot spool in with the brass insert, then hold it in with small tie wire to keep spring from pushing it back out. Once they're installed and retained with the wire, set the plate, start the bolts, then cut and remove wire. Sounds like the new design is more wrench friendly.

 

[RobVG]

OMG ATCO! That's exactly what I did with those! :cool2

But I used cable ties.

Sounds like the new design is more wrench friendly.

Yup, It darn near takes the fun out of it...

 

[willie59]

OMG ATCO! That's exactly what I did with those! :cool2

But I used cable ties.



Yup, It darn near takes the fun out of it...

LoL, great minds think alike!

I used to work on a good number of aerial lift trucks used by cable tv techs. They use a thin aluminum wire that they wrap around the line cable and the support cable between poles. Those trucks would have piles of short roles of that wire in the back of their truck, too short for them to use for another cable wrap. Very bendable and pliable wire. It works perfect for repairs like this.