B1700 HST 4WD - hydro fluid running from mystery hose

[Brewer]

Hi all,

I'm losing a bit of hydro fluid from a black ~1/2" hose below my right foot (between the engine and the cockpit). It seems to be an intentional vent or overflow, and comes down from between the fuel tank and the dashboard cowl. I haven't yet been able to remove the throttle lever pin to get the cowl off and have a proper look.

Any ideas what this hose is connected to? Transmission vent? Overpressure dump valve?

I managed to fill a cup in just a couple of minutes operating, the fluid looks muddy and greenish, is this normal for hydro fluid in use? I'll let it settle overnight and see if it holds any clues tomorrow.

 

[North Idaho Wolfman]

There is no hydraulic system overflow.
It sounds more like a radiator overflow issue.

 

[Brewer]

Thanks Wolfman. It's oil, not coolant (although I did wonder if the green tint was a clue). It's settled out a bit and looks less muddy now, no water in it as far as I can tell, must have been a bit aerated.

Whatever it is connected to is right at the back of the motor, tucked up between the back of the fuel tank and the dashboard. Is the hydro pump up in there maybe? Or power steering components?

 

[100 td]

Perhaps clutch housing or diesel overflow?

 

[Brewer]

It's definitely not diesel or engine oil, it has to be the hydro fluid - but it's literally pouring out when I work the machine. Don't know anything about the clutch on these, could that be it? What could cause such a dramatic venting of fluid like that?!

 

[North Idaho Wolfman]

Well I stand corrected, that vent pipe is rather unique to that model, , the hydraulic vent pipe is normally under the seat.
It sounds like you are sucking in air on the intake of the hydraulic pump, that will cause it to foam and thus flow out the vent pipe.

 

[Brewer]

It sounds like you are sucking in air on the intake of the hydraulic pump, that will cause it to foam and thus flow out the vent pipe.

This sounds exactly like the symptoms I have, thanks Wolfman!

So the problem will most likely be in metal lines (or seals) between the reservoir under the seat and and the pump which I guess is at the back of the engine there?

 

[North Idaho Wolfman]

Inspect all of the yellow, look for a seeping leak.

 

[Brewer]

Oh you are a star, thanks mate! I'll let you know how I get on.

 

[Brewer]

OK, I'm a bit stumped.

The line you marked looks fine, I can't see any hint of a leak anywhere along it.

However there is some oiliness at the rear (transmission?) close to that fitting - but it looks like it is coming from the hose not the hard line. As far as I can tell, that hose is a return line from the FEL control to the reservoir, so it shouldn't be drawing any air?

There is also a fair bit of oily dirt caked around the hydro dip tube, so there may be a bit getting up past the dipstick o-ring - but again it's difficult to see it drawing air in that way?

 

[Daren Todd]

On 40 in the picture. Is there a rubber coupler on it?

If so, for cheap insurance, I would replace that rubber coupler All it takes is a pin hole in it to start sucking air. And It may not show up as a weeping leak. I would also change the hose clamps from the spring loaded type, to a screw type clamp.

 

[Brewer]

Hi Daren, thanks, part #70 is a short rubber hose, is that what you mean? I removed and reinstalled it with new hose clips, but it hasn't fixed the problem.

I was about to order a replacement when I figured I'd try running the machine without the FEL for a while - and without it I seem to get no oil. It is difficult trying to recreate the load on the hydraulics that some serious FEL work gives, but I got it nice and warm and even tried driving it with the brake on to give them something to whine about and I couldn't get them to foam/leak.

Is it possible that the FEL hydraulics are introducing the air?

I think I will replace that hose in my photo (it has also worn where it passes over the belly mower lift mechanism), maybe that will do it but I'm still not sure how/if air could get into what is essentially a low pressure return line?