Hydraulic chatter L3240HST

[amigauser]

I noticed that if I run the tractor at around 2100 RPM or slightly higher there is a sort of chattering like sound using the FEL controls or turning the steering wheel on the tractor. I never noticed it before but it could be because I have not run it at that exact RPM before. If I raise or lower the engine RPM the noise stops. At first I thought it was a problem with the steering as I first noticed the sound while turning but it made the same sound when raising or lowering the FEL. Sound seems to be coming from the right side of the engine, maybe hydraulic pump?

It will make the noise either moving or just standing still but apparently only at around that RPM.

Has anyone else with a Grand L40 seen something similar? I have under 75 hours on it and did the 50hr service myself back in May with SuperUDT and all Kubota filters. It is still under the 2 year warranty so I want to have it addressed if there is a problem. Everything seems to operate normally though.

 

[amigauser]

Bump

I can't believe there are no other L3240hst owners here.

Can someone with a L3240hst please check between 2000 - 2100 engine RPM to see if they get a hydraulic ticking/chatter when turning the steering wheel?

It is definately RPM specific as the sound disappears with lower or higher RPM by just lowering or increasing the throttle. I just want to find out if other L3240hst's act the same or if there is a problem.

Thanks.

 

[leonz]

The issue is one of air bubbles and or cold oil in the piping and their compressing and expanding.

1. depending on the engines low idle speed the pump cannot pump enough oil at the 2100 R.P.M.
a. depending on how old the tractor is it may have a bad steering valve

2. You may have a sticky loader spool valve in the tractor creating cavitation; I am uaware as to whether they are using a standard spool valve system or a gimbaled valve set up with the spring pressurised poppets etc.


a. If the steering motor at the end of the steering column is bad the oil will whistle/chatter-
if it has a steering motor.


b. the pump section for the steering circuit could be going bad also :^0

leonz

 

[amigauser]

Leonz, thanks for the input. Why does it only make the sound at that RPM then? If I lower or raise the throttle to lower or increase the RPM's it does not make the sound? Any change in RPM above or below that point and the sound disappears. It does it cold or hot so the oil temperature does not seem to make a difference.

 

[leonz]

The filter may be an issue if it is restricted

and does not have a bypass too.

The oil being pumped at the lower r.p.m.

is moving slower and the oil moving at the higher

r.p.m. is posssibly surging through the relief because

it may have a lot of air in it the oil.

 

[kcender]

I have an L3240HST and have never noticed a noise like you are describing.The tractor has about 270 hours on it.I generally run it at about 2000 rpm which would not cause the noise at that speed.When using the backhoe I run it at around 2100 to 2200 rpm and have never noticed a noise like you are describing.When I have it out this weekend I will run it at 2100 rpm and see if I hear a noise or chatter.I will let you know.

 

[Baby Grand]

Have you tried setting the throttle at the speed that the noise is loudest at and then applying your safety brake and flipping your seat forward so you can dismount and find exactly where the sound is coming from?

The reason I ask is that starting a few months after taking delivery of my
L3240GST I heard a sound that seemed to be coming from the left rear engine area, but only in a narrow RPM range. I had myself convinced it was gear chatter of some sort and it sounded like nickles and dimes rattling around in a coffee can. Then one day I was doing something with the machine in neutral and the idle set high. When I walked around the front I heard the rattle and lifted the hood. Somehow, the right side of the battery hold-down clamp (at the very front of the engine bay) had come loose and was making all the noise. A few turns with a wrench and no more rattle.

Long winded, I know, but the point is I had completely misjudged where the sound was coming from until I actually stood right next to it.

-Jim

 

[amigauser]

Good thoughts. I normally run it at around 2000 RPM so I never noticed the sound until recently. I will try and pin the sound location down better tomorrow. Otherwise, off to the dealer in the very near future.

 

[amigauser]

Well, it ended up being harmonics like I originally thought it might be.

I ran the tractor out on my driveway this morning and crawled all over and under it with it running to try and determine the noise source. The sound seemed to be coming from the hydrostatic transmission itself so that got me worried. I started grabbing the metal hard lines to see if any were vibrating and when I grabbed onto one of them the noise stopped instantly. The vibrating line was the source of the sound and only at that slightly under 2100 RPM position. I just zip tied that line to another adjascent line and that eliminated the sound. Lesson learned.

Thanks again for all of the suggestions. At least I know now my baby is ok.

 

[lawn_king]

Good job!