Backhoe Backhoe slow and noisy for 20 minutes

[PaulT]

Originally posted this in Kubota Owning, but thought that it was better posted here. Also, anyone with other hoes that might have some suggestions are more likely to see it here.

I have a Kubota 4672 hoe, and was digging some shallow trenches for drainage over the last 2
weekends. I noticed that for the first 15 minutes or so, the hoe is extremely slow and very
noisy. The fluid reservoir is between the lines on the dipstick, and the engine is running at
the recommended RPM. It seems like tiny air bubbles are being flushed from the rams during
warm up.

A important note:
The valve was leaky when I received it, but the hoe worked great (the side 2 side swinging was VERY fast).
I used it to dig out a few stumps and dig one huge hole (10x8x6), and it worked like a
charm, but was very messy and needed to be topped off once in a while. I finally got
frustrated witht the mess and tightened each hose fitting into the valve body. I only
tightened the fittings (not the relief valve setting), but wasn't sure on the torque to use. I
could not find a torque spec sheet for these fittings, so I was just using my "feel".

This warm up stuff only began happening since I did that. Any thoughts? is this what
happens to hoes after they break in (I've got 64 hours total on the new 2710, with about
25 hours on backhoe work). Oh yeah, I've greased the hoe as indicated.

PaulT

 

[hayden]

The circumstance certainly point to the valve and what you did.

Were you able to see where the valve was leaking and what exactly did you tighten? It certainly shouldn't have been leaking in the first place. I've got a 4690 which is essentially the same thing and I haven't had any "warmup" behavior like you describe. It does sound like when you tightened things to stop the leaking it also had some other effect.

The swing speed is fast compared to the speed of other operations - it's just the way they are and others have noticed/complained too. I don't think you have a problem there.

High techie, reciently founded a startup company and struggling for tractor time.

 

[allmobile]

Typically a hydraulic problem that improves when the oil warms up is a suction screen or filter problem.

Brian

 

[PaulT]

Well,

Thats an obvious one I should've eliminated/w3tcompact/icons/blush.gif. I guess I'll change the filter and see how it works then. I don't think anything got into the lines while I was removing and then reinstalling them more tightly, but you never know. Also, since its new, there could be stuff from the manufacturing process that was in the tank and finally found its way into the filter. Does anyone know if there are any other screens, etc. on this hoe that I should check?

PaulT

 

[WVBill]

I find that the FEL (separate hydraulic system) on my B6100 is slow and noisy for 10 - 15 minutes when it gets cold outside. Last winter I drained, flushed and cleaned the screen/filter but it was still noisy & slow. When spring came the noise & slowness went away. Also, last winter when I was flushing the system (with a 50/50 mix of oil and diesel fuel) there was no noise or slowness.

My conclusion is that the 10W30 Motor Oil specified by Kubota for the FEL hydraulic system is too thick when cold. So with winter coming I'm considering alternatives.

Is Hydraulic fluid "thinner" than motor oil? I might also try 0 W 30 oil - I think I've seen that at Pep Boys...

Any thoughts?