DK40SE Squeal When Moving in Reverse.

[kattywumpus]

I have a new DK40SE. After 30 minute of use the tractor started generating a very loud squeal when moving in reverse. The squeal sound like a brake sticking. The engine was running at the recommend RPM for HST if not higher. The HST was in low range. I was using a 6' angle blade to grade a driveway. Once the tractor was moving in reverse the sound would start. When I hit the brakes the sound might stop or might not, but the minute I hit the forward petal it would stop. I'm sure the dealer will fix it, but I'm wonder what the cause is.

 

[art]

It could be a hydro relief valve problem as you said the brakes didn't make any difference.

 

[kattywumpus]

I was thinking the same thing. One change to the description of the problem it appears it really takes 1 1/2 hours to 2 hours of steady use before the noise occur.

 

[Highbeam]

Is it a chatter like a chirp chirp chirp or is a steady squeal like a waaaaaaaaaaaa?

I'll get some odd chirp sounds in reverse sometimes. Chirp hear a chirp there. Goes away when the clutch pedal is depressed just enough to take up the slack which tells me it's the throwout bearing.

Try setting your foot on the clutch pedal while the noise is going.

 

[Johnjudge007]

my tractor makes a squealing sound in both directions but only under strain

 

[roger 4400]

Try to adjust your brake pedal a little bit lower. My new MF 1643 HST was slowing and loosing rpm instead of increasing after 2 hours of mowing (HST oil hot). Dealer came home adjusted the pedal lower and since then no problem.. When hst oil is too hot the brake pads that are in the oil are expanding because of the heat and slow the tractor, making the hst under more stress . Good luck. Roger

 

[MichiganIron]

Sounds like HST Relief valve. Contact your dealer.

 

[kattywumpus]

Highbeam, I think the sound depend on how long the tractor been running. Initially after an 1 1/2 hours of use its a random or odd chirp sounds in reverse. And when either HST forward or reverse pedals are released a quick steady squeal occurs until the tractor stops. After around 3 hours of use when the tractor is placed in reverse the sound is more steady and very loud. My wife can hear it in the house. At that point I shutdown the tractor and let it cool down.

Roger, it does sound so much like a brake squeal and it does seem like the brake pedals are tight. I really have to push really hard to engage the parking brake, so you maybe on to something.

So far the dealer hasn't been much help. His response was I was not running the tractor at the correct RPMs. When I would go in reverse I would drop the RPMs to 2500 RPM were the red triangle is on the gauge. I did this because I was backing down a long driveway without a load on the tractor. When I graded forward I would increase the RPMs to 2900. The dealer had told me for best HST performance the RPMs should be at the red triangle (2500 RPM) or above. But the manual say 2600 RPM, so his answer was I should running it at 2600+ instead 2500. I doubt very much an extra 100 RPM will resolve the issue since the problem seem to be temperature related. Once the tractor cools down the noise does not occur for another 1 1/2 to 2 hours. But I will give his suggestion a try.

Thanks

 

[Highbeam]

I do plenty of HST work with RPMs WAY WAY below the red triangle. I like burbling along at 2000 for lots of work and while it may not be the "best" performance I can assure you that it works just fine. You could say the same thing about gear tractors, that for the "best" performance the engine should be at peak HP or torque RPM but we all know that the rest of the RPM range makes power too.

Try touching the clutch pedal when it is squealing to take up the slack in the clutch mechanism. Just to see. It doesn't cost anything.

Do you have a hydro cooler on that model? If you notice a direct relationship between heating the machine up and the noise then the fluid may be getting hot, thinning out, and bypassing a relief. When it is hot enough to squeal, open the hood and put your hand on the hydro cooler and see if it is hot. On my CK I have a hydro filter behind my right foot that I can feel with my hand from the operator's seat to dense if the hydro fluid is too hot.

 

[MichiganIron]

As the tractor warms and the hydraulic fluid gets warm, the pressure relief in the hydrostat could open prematurely. This will normally happen under load, like the brakes were stuck.

If you hear the squeal, and you are sure the brakes are released, we would look to the HST pressure relief next. The squeal would come from the middle of the transmission case.

Put the range selector in NUETRAL !!!, then try to rock the tractor gently. You'll be are to tell if the brakes are locked.