Another HST noise thread.....

[Verticaltrx]

BeezFun- I'll have tp pay more attention to where it may be coming from. I swear it sounds like the HST pump is starving to get fluid out. I'm only hearing it driving up hills or if the terrain changes from smooth to incline. Its like when the pump is trying to pump out more juice to keep the tractor going through the terrain, it hisses.

It might be the relief valve opening on the HST. If that is the case it could be that either it's not properly working, or you are using too high of a range when going up hills. I know that my B3200 won't go up moderate hills in high range, and if I push too hard on the pedal in that situation it will open the relief valve and basically stop forward movement. The only time I have experienced that in middle range is when pushing too hard with the loader, never been able to stall the HST in low range. I haven't paid close attention to the sound it makes when this happens, but I think it might be similar to the hissing sound you described. If that's the case and you're not using to high of range for the situation, you might need to look at the relief valve. I can look in my service manual later if you needs details on what to check.

 

[General Lee]

It might be the relief valve opening on the HST. If that is the case it could be that either it's not properly working, or you are using too high of a range when going up hills. I know that my B3200 won't go up moderate hills in high range, and if I push too hard on the pedal in that situation it will open the relief valve and basically stop forward movement. The only time I have experienced that in middle range is when pushing too hard with the loader, never been able to stall the HST in low range. I haven't paid close attention to the sound it makes when this happens, but I think it might be similar to the hissing sound you described. If that's the case and you're not using to high of range for the situation, you might need to look at the relief valve. I can look in my service manual later if you needs details on what to check.

Yea, when you get a chance let me know what I need to do and where the relief valve is located. Thanks a million

 

[David_Kb7uns]

I wouldn't say "hot". Yesterday I pulled the tractor out to pull out my other tractor from the mud and the 3200 only basically ran for 7 or 8 minutes before pulling the tractor out. While coming back up the hill it was making the noise.

Have to ask, but were the correct Kubota filters and UDT or SUDT used in the change, otherwise may be a problem there.

David Kb7uns

 

[General Lee]

Have to ask, but were the correct Kubota filters and UDT or SUDT used in the change, otherwise may be a problem there.

David Kb7uns

I can only assume they were the right filters. I got Kubota filters from the dealer and they fit. Also used Kubota SUDT. The noise started before I did the filter changes though.

 

[General Lee]

I went out this evening to take a closer look at things. Fluid level seemed a little low. Just above the first notch on the dipstick. Manual states anywhere within the first and second notch is *acceptable*. I added about a quart of fluid to bring it up to the top notch. The noise doesn't seem to be as loud now but its still there especially in high gear. I don't know, may just the normal operation of the pump and I haven't noticed it before recently??
As one poster stated, it may be a vibration. So I listened closely and it does sound like it could be, only its evident when the transmission surges at the demand of fluid. For instance when pushing the forward peddle or going up inclines and the tractor is calling for more fluid.

 

[DiezNutz]

I've only experienced my HST relief valve a couple of times, and it's more of a squealing/whistling sound... not really a hiss. Unless that sounds right to you, it's probably something else.

 

[Verticaltrx]

I looked in the manual about the relief valve and in order to test it you have to have a special 5,000 psi gauge and the fittings to plumb it in to the tractor. Basically there are three ports on the bottom of the HST: P1, P2, P3 and you test one for the forward relief valve and one for the rearward relief valve. If you have the means to do it I can give you more specific details, but it sounds like this may not be your problem.