M9040 "Hissing" Noise

Ford tractor · Feb 28, 2012

GregHammerstein said:
Thanks for the replies guys. I previously checked the hydraulic valves to see if operating them had any effect on the noise but they do not. My M9040 has three additional optional valves as well and I checked them also. I will definitely check the turbo-charger lines but it's for certain that pumping the brakes stops the hissing (at least for a minute or two). Appreciate everyone's help very much.

Does it hiss when NOT under a load or only when loaded? The turbo won't be building pressure without a load on the engine. "Assuming" you are operating the machine, hear a hiss, tap the brakes a few times (probably with the clutch in?) and the engine unloads, pressure goes down and the hiss stops. That would make me suspicious of a loose line between the turbo and intake manifold.

Other thing could be the "pop off valve" that keeps the turbo from over pressuring the engine. It shouldn't be bleeding pressure very frequently. If it's the cause, you may need to have the dealer adjust or replace it.

There's more, but those are the ones that come to mind. Maybe that will give you a direction to look.

5030 · Feb 28, 2012

You mean the 'waste gate'. You don't hear that anyway. All it is, is a sealed diaphram that senses boost pressure and actuates a butterfly vane in the turbo housing, limiting boost pressure...... It does have a hose attached but just a tiny one..... I doubt you'd hear it over engine noise.....

GregHammerstein · Feb 29, 2012

Thanks for the suggestion. Hissing noise is present loaded and unloaded. Clutch depressed or released. Operating the clutch does not have any affect. Operating the hydraulic valves does not have any affect. So far the only thing I've been able to consistently reproduce to eliminate the hissing sound is operating either one or both of the brake pedals. One or two depressions doesn't usually clear the noise. Three or four times or more is always effective. One single depression with continuous application also will NOT clear the noise.

GregHammerstein · Mar 4, 2012

Quick update. My dealer spoke with the local tech rep. They all agree it's likely being caused by debris in the pressure side of the brake valve in the pressure port fitting which houses the filter. The service manager was able to come by my place over the weekend and listen to the noise himself. He also agrees it's coming from the brake valve. Plan is to pull and replace the filter and check for debris in the port. The tech rep says there is an orifice in this port as well and if the debris is on the non-filter side of the orifice the valve will need to be replaced. This is dejavu for me because my M7040 made an unusual vibrating noise brand new off the lot and it turned out to be a metal shaving inside the hydraulic 3-way valve. Kubota knew exactly what this was when we described the noise to them and we went right to the valve and found the metal shaving inside. Will provide an update once we get inside the valve.

5030 · Mar 14, 2012

Interesting. Both my large frame Kubota's 'hiss' or should I say make a sloshing sound. Both are way out of warranty however.

GregHammerstein · Mar 14, 2012

What model Kubota tractors do you have and what years are they?

5030 · Mar 15, 2012

GregHammerstein said:
What model Kubota tractors do you have and what years are they?

Lets see, a 105 S (which is 16x16 hydraulic shuttle) and it's 6 years old and a M9000 HDCC3 (12x12 hydraulic shuttle, 2 speed PTO) and it's 7 years old. I really have no issues with either other than the sound. I've changed the fluid and filters more than once (expensive change by the way at almost 15 gallons in the gearcase on each and fluid costing around 150 bucks a pail (5 gallons)). The 105 has around 400 hours on it and the 9 is over 1000.

I run Chevron full synthetic fluid in both. It's Kubota specification but it's orange colored.