M62 observations and questions

[Seven Gables]

Acts to me like your port relief valve on the boom lift circuit is simply set at too low of PSI, assuming it has one. With a pressure guage it’s a simple adjustment that I occasionally have to make on my excavator to match the requirements of the tool I’m running with that circuit. That being a new under warranty machine I’d definitely let the dealer check/adjust to proper spec. Possibly that being a m62 with longer stick it needs to be set slightly higher than was necessary with the m59 .

 

[rScotty]

Acts to me like your port relief valve on the boom lift circuit is simply set at too low of PSI, assuming it has one. With a pressure guage it’s a simple adjustment that I occasionally have to make on my excavator to match the requirements of the tool I’m running with that circuit. That being a new under warranty machine I’d definitely let the dealer check/adjust to proper spec. Possibly that being a m62 with longer stick it needs to be set slightly higher than was necessary with the m59 .

You know, 7G, that's a real possibility. The M59 - and presumably also the M62 - do have those overload relief valves you mention. In fact, there are a pair right there on the boom control valve for the boom circuit. One each for each side of the boom cylinder circuit being protected. That would be a very simple fix.

The function of the overload relief is just as you say - to protect the control valve circuit from outside forces. And extending the dipperstick would trigger that relief since it would appear to be an outside force on the boom cylinder circuit.

There are also overload reliefs on the dipperstick, bucket, and something similar on the swing circuits. All those circuits have a pair of overload relief valves. There are other relief valves that protect the pump pressure side of the control circuit, but that isn't the problem here.

The thing is, it is rare to trigger those overload relief valves. They tend to be set higher than the pump pressure psi so you can use full power on the hoe. Checking them is a simple matter. It just takes an adapter, a tee fitting, and a pressure gauge. Any dealer will have it. The relief valves themselves are easy to swap out. Might as well check the load check valve between the ports while you are there. O rings cost two bucks...

On our BH the overload relief valve is set (by Kubota) so that the whole front end and loader bucket will come off the ground before the boom cylinder moves at all. That's typical. In fact, people break backhoes all the time by loading up the front bucket so that the boom will lift more without the tractor rearing up. I've done it myself.....
Uh, I better add an edit. I have done that - put a load of dirt in the bucket to keep it from rearing. But so far have not broken anything. That's probably due more to good luck than good practice. Definitely not something to recommend.

rScotty

 

[mikester]

I tend to notice a hydraulic oil smell after running the BH on my M59 do you guys get that as well?

 

[rScotty]

I tend to notice a hydraulic oil smell after running the BH on my M59 do you guys get that as well?

No, not on mine. I kind of expected to smell them because sitting in the backhoe position puts us us right above that hydraulic sump vent.

But I tend to do all my work with the engine running fairly slowly - at a high idle. So nothing gets very hot. Maybe that's it. Plus I try to at least look at the hydraulic radiator to see if it is clean - it always is.

I wonder if different fluids smell different. I've never noticed that, but maybe so since they sure do sound different.
So far I've run New Holland Ambra G134, SUDT, and JD Hy-Gard. The New Holland was best for sound. I'd like to try Super UDT2, but don't yet trust Kubota fluids.
rScotty

 

[Smokeydog]

I tend to notice a hydraulic oil smell after running the BH on my M59 do you guys get that as well?

Haven’t noticed a smell. Use Sudt and factory filters.

Want to open the overload valves on the swing and boom valves to make check for debris and Oring condition. Hard to believe a tiny bit can cause intermittent total loss of function. Can hear flow but no force or movement.

 

[rScotty]

Do you see two different M59 valves in the parts pictures? Or different settings? Which are which? They don't seem to match the Shop Manual.

The M62 parts on Messicks parts site seems to show a a completely different set up for the valve stack and overload valves - and they are rebuildable. Maybe Kubota is working on the problem.

 

[whoodle]

Thanks guys!
Happy new year to all. The dealer increased the relief valve when installing the rear hydraulics recently. I haven’t checked the function yet, but I plan to go out to the very same stump. It sounded like it was a very easy fix. I tend to run my back hoes at about 2000+ RPM and they all smell like hydraulic oil after a while.

 

[Hersheyfarm]

Hydraulics work best at rated rpm’s. Somethings like ctl’s need at least 1/2 throttle because 1 pump supplies another and can starve it. Hence the whine at low rpm’s. I almost always ran my m59/m62 at 3/4 to full throttle. Same with my mini x’s. And yeah you smell fluid when you’re good and warmed up, especially if your smeller works good. Some might not pick up on it as good as others.

 

[rScotty]

Thanks guys!
Happy new year to all. The dealer increased the relief valve when installing the rear hydraulics recently. I haven’t checked the function yet, but I plan to go out to the very same stump. It sounded like it was a very easy fix. I tend to run my back hoes at about 2000+ RPM and they all smell like hydraulic oil after a while.

Great! From the shop manuals, the M59 and M62 have very different backhoe control valve stacks. The relief and check valve design of the M62 looks like a big improvement. They are simpler, rebuildable, and way less expensive. Let us know how the adjusted relief setting works.

I still haven't added a pressure gauge to the backhoe myself, although I have one on one loader.

Check around and you will hear different operators running their machines at different RPMs to suit themselves and what ever job they are doing. No reason not to go full throttle when digging in dirt, and no reason not to go at an idle when placing boulders buildng a berm. As for RPM affecting BH lifespan, I've never known it to make much of a difference.

Back in the day we used to decide if differential and hydraulic fluid needed changing by opening the fill plug and smelling it. It was such a common test for mechanics to do that nobody really questioned if it was right or not. If it smelled burnt it got replaced. Trouble is, most of it smells kinda burnt to me.... so I sure don't know.
rScotty

 

[whoodle]

Great! From the shop manuals, the M59 and M62 have very different backhoe control valve stacks. The relief and check valve design of the M62 looks like a big improvement. They are simpler, rebuildable, and way less expensive. Let us know how the adjusted relief setting works.

I still haven't added a pressure gauge to the backhoe myself, although I have one on one loader.

Check around and you will hear different operators running their machines at different RPMs to suit themselves and what ever job they are doing. No reason not to go full throttle when digging in dirt, and no reason not to go at an idle when placing boulders buildng a berm. As for RPM affecting BH lifespan, I've never known it to make much of a difference.

Back in the day we used to decide if differential and hydraulic fluid needed changing by opening the fill plug and smelling it. It was such a common test for mechanics to do that nobody really questioned if it was right or not. If it smelled burnt it got replaced. Trouble is, most of it smells kinda burnt to me.... so I sure don't know.
rScotty

Funny!
My bro is a crack mechanic and we alway judged tranny and gear oil by smell. Relief valve adjustment worked well. Now predictable lift. Noticed the float on the loader does hold for squat. Maybe a detent adjustment. Cold and snowy here so the m62 is hibernating and I reverted to the old 110 for snow blower and v plow.