DK40SE Squeal When Moving in Reverse.

[grsthegreat]

Sorry for the confusion.

No the squeal was still there and the HST charge pressure was the same. What I measured was the pressure before the filter.

You should get yourself a service manual. Check with your dealer they are about $100 or so. There is some good information in there and a bunch of stuff that should be in the owners manual.

Got one...ive used it a few times already.

 

[kattywumpus]

Kattywumpus:
Did your dealer do a pressure test on your HST and what were the results. I was not implying it was the high pressure reliefs but rather the charge relief valve. The charge relief controls the fluid on the low pressure side. I am curious if the low readings I am getting are shared or local to my machine. If the HST is not getting enough fluid it will cavitate and make all sorts of noise.

I don't know the details concern the dealer pressure test. I reviewed my emails with TRC (my purchasing dealer) and this is all I could find "Stan has detected a 1000psi drop off in the hydraulic pump after the tractor warms up (1hr +)". My understanding is, there is a Kioti tech document concerning the pump issue and is the reason the pump was replaced.

If I remember correctly the precharge line pressure for the HST is only around 300 psi. Currently I don't think this is related to lack of fluid getting to the HST based on my past conversations with Kioti support. Plus since the squeal doesn't occur going forward. My understanding is Kioti replaced the metal line with a flexible rubber hydraulic line to minimize the conversion fluid cavitation to sound.

When I get a chance I will review my service manual for notes I made during Kioti's visit last year.

Looks like I need to get some Hydraulic pressure gauges.

 

[kattywumpus]

I knew someone would pick up on the irony of my post

So KWumpass, If Kioti knows so much about what is NOT causing the squeal- do they know ANYTHING about what IS causing it?!

My belief is Kioti has a good idea were the squeal is coming from but not why it's occurring. Tom Martell told me during last fall's visit they had already tear down one tractor and HST drive, and could not find any issue. I believe they even sent the HST drive back to the manufacturer. I think they isolated it to a couple of valves or area in the HST drive based on sound originating point.

 

[tnewbern]

Restriction found and removed...

Pressure is up and the squeal is gone!!!

Full report at 10:00.

 

[IslandTractor]

Restriction found and removed...

Pressure is up and the squeal is gone!!!

Full report at 10:00.

Congratulations. I'll be very interested to hear what the restriction was and why it affected only a minority of the DKse tractors.

 

[tnewbern]

This is not finished or over and I am waiting for parts for the final conclusion but here is what I have so far.

The HST pre-charge pressure is supposed to be 255 PSI. The pressure is supplied by the secondary pump (power steering circuit) and controlled by the charge relief valve in the HST. I found the charge pressure low 205 PSI as per the manual I went looking for a restriction. I measured the pressure at the output of the power steering and found the pressure to be high about 450 PSI. This is indicative of a restriction or leak between the test point and HST. I traced this all the way to the HST filter.

So I bit the bullet and replaced the new (about 50 hours) HST filter. I know its expensive and I did not want to do it but man there is a restriction so what else could I do. So I did it and was I pissed to see it was still the same. High pressure before and low pressure after. GRRRRR.

In a last ditch effort I decided to try and test the pressure at the HST. This is very tricky as the connections are hardline banjo fittings. So I removed them and what to my surprise. Why is this banjo bolt different than the rest. Why is this bolt not tapered down like the others to improve flow (see attached photo). Could it be.... off to the hydraulics shop to build a test rig to check the pressure. Ouch those metric fittings are expensive but this should work.

Armed with some shiny new fittings I connected the filter to the HST including a test tee to may handy pressure gauge. Fired up the tractor and wow..... the pressure is 260 - 270 PSI right where it should be. Warm it all up and check the charge pressure and relief valves. Just like the manual says right on the money. Perform the tasks to get the squeal but wait its not there. Call my new best friend to spread the news.

So it would appear that is the bolt specified in the parts manual but wait. That was not always the part (the restricted banjo bolt). There is an ECO (engineering change order) that modified this part. I wonder when that went into effect. I would bet right about or before the time our tractors were built. The banjo fitting is about 2.5mm shorter on the filter side (were the new bolt was specified) and the new bolt is shorter. Ok so they wanted a shorter banjo bolt but somehow the new bolt did not have the taper to improve flow (see the attached photo).

Now its time to exercise the tractor. Remove the test equipment and hookup some implements. After over an hour of abuse no noise. I can usually get the squeal in about 5 minutes at low RPM's and in this heat get constant squeal in less than 10-20 minutes of work. I have it down to a science.

So in conclusion this is not over and the engineer in me is still looking for proof and answers. Still need to show the correct bolt vs ECO bolt pressure differential but I have to wait as its not in stock. So for now I can avoid my shiny new tractor being split in 2 and see how things progress. Repeat "Small things cause BIG problems" or "Simple things cause Complex problems" or ...

So how are your pressures? Do you have the mystery banjo bolt in the top of your HST filter? I hope this inspires you to check and not just blindly trust other will. At the very least ask. Don't be afraid to ask questions and make sure you understand the answers. Most people who understand are glad to give you an explanation. The ones who don't usually get angry and take your inquire as a challenge to there ability.

Tom

 

[dourobob]

This is not finished or over and I am waiting for parts for the final conclusion but here is what I have so far.

Most people who understand are glad to give you an explanation. The ones who don't usually get angry and take your inquire as a challenge to there ability.

Tom

Tom
On behalf of the non-engineers, thank you for your great work on this. I am sure that I and many others are eagerly waiting for your "proof and answers"

Bob

 

[Coyote machine]

This is not finished or over and I am waiting for parts for the final conclusion but here is what I have so far.

The HST pre-charge pressure is supposed to be 255 PSI. The pressure is supplied by the secondary pump (power steering circuit) and controlled by the charge relief valve in the HST. I found the charge pressure low 205 PSI as per the manual I went looking for a restriction. I measured the pressure at the output of the power steering and found the pressure to be high about 450 PSI. This is indicative of a restriction or leak between the test point and HST. I traced this all the way to the HST filter.

So I bit the bullet and replaced the new (about 50 hours) HST filter. I know its expensive and I did not want to do it but man there is a restriction so what else could I do. So I did it and was I pissed to see it was still the same. High pressure before and low pressure after. GRRRRR.

In a last ditch effort I decided to try and test the pressure at the HST. This is very tricky as the connections are hardline banjo fittings. So I removed them and what to my surprise. Why is this banjo bolt different than the rest. Why is this bolt not tapered down like the others to improve flow (see attached photo). Could it be.... off to the hydraulics shop to build a test rig to check the pressure. Ouch those metric fittings are expensive but this should work.

Armed with some shiny new fittings I connected the filter to the HST including a test tee to may handy pressure gauge. Fired up the tractor and wow..... the pressure is 260 - 270 PSI right where it should be. Warm it all up and check the charge pressure and relief valves. Just like the manual says right on the money. Perform the tasks to get the squeal but wait its not there. Call my new best friend to spread the news.

So it would appear that is the bolt specified in the parts manual but wait. That was not always the part (the restricted banjo bolt). There is an ECO (engineering change order) that modified this part. I wonder when that went into effect. I would bet right about or before the time our tractors were built. The banjo fitting is about 2.5mm shorter on the filter side (were the new bolt was specified) and the new bolt is shorter. Ok so they wanted a shorter banjo bolt but somehow the new bolt did not have the taper to improve flow (see the attached photo).

Now its time to exercise the tractor. Remove the test equipment and hookup some implements. After over an hour of abuse no noise. I can usually get the squeal in about 5 minutes at low RPM's and in this heat get constant squeal in less than 10-20 minutes of work. I have it down to a science.

So in conclusion this is not over and the engineer in me is still looking for proof and answers. Still need to show the correct bolt vs ECO bolt pressure differential but I have to wait as its not in stock. So for now I can avoid my shiny new tractor being split in 2 and see how things progress. Repeat "Small things cause BIG problems" or "Simple things cause Complex problems" or ...

So how are your pressures? Do you have the mystery banjo bolt in the top of your HST filter? I hope this inspires you to check and not just blindly trust other will. At the very least ask. Don't be afraid to ask questions and make sure you understand the answers. Most people who understand are glad to give you an explanation. The ones who don't usually get angry and take your inquire as a challenge to there ability.

Tom

AWESOME!:thumbsup: I'm certain you have found the problem! I can see how the lack of machining of the shorter bolt would make it want to squeal like a stuck pig! And, if it wasn't the problem wouldn't the squeal have returned like it did after you did the first HST filter change?

I'm curious, how are you able to find things like the ECO's and such, and get the side by side pic of the two bolts in question?

What are your thoughts on the possible damage(s) that might have occurred in the circuit with the higher than normal pressures, due to the restriction?

Can you site part number(s) for the correct bolt so those of us who have the squeal can get the new bolt in place?!

I'm still in shock- this is/ was the thing that kept me from being able to really like my new tractor, and wish I had stuck with my DK-35 with no squeal!!

Your 'proof' can be further verified by kattywumpus getting a bolt in place on his 'squealer'. Repeatability is certain to satisfy the engineer in you, right?

I'm going to my dealer tomorrow to 'demonstrate' the squeal. I will review your post with him in detail and have them pull the bolt and see what it looks like.

Will report my findings.

CM Out.

 

[tnewbern]

I have X-Ray vision, ESP and a supper secret seventh sense. Did I mention one of my parents was from Crypton. Seriously, the bolts in the picture are from my tractor. As for the ECO talk to your dealer. Ask them for a parts breakdown of the circuit. I can't say for sure that this ECO caused this or when it was put into effect. The only thing I do know is that was not always the part number for the bolt in question. Much of the rest is speculation on my part from experience. Maybe this started because of a leaking banjo bolt. Here is how I envisioned it going the name have be changed to protect the identities of the actual persons involved.

Bill: Hey Fred and Joe we are getting a report of leaking banjo bolts on the top of the HST filter can you guys look into this.

... Bucket, Wrench !!!Ouch!!! Bandaid, Rag ...

Fred: Hey Joe this bolt seems like it might be a little long.

Joe: Yeah your right we should shorten that. Do we have any shorter bolts?

Fred: This one is shorter give it a try. Yep it fits now lets see if it works.

... 5 minute later...

Joe: Yep that did it no leak.

Fred: Hey Bill we found the banjo fitting on the top is about 3mm shorter than the rest and the bolt may interfere and not completely seal. We used this bolt but note it is not the same and came from the rear remote circuit.

Bill: We found a solution but we need to source and order a new bolt and this will take some time. We used this one as a temporary fix but note is not the proper bolt we need a high flow fitting for this circuit.

BOSS: We can't afford any delay use that part and we will look into getting the proper bolt if cost and time allow.


Now seeing that this squeal only effects a small group of tractor I imagine they ordered (or manufactured) the proper high flow bolt and started using it. For those of us unfortunate few we get the temporary fix. Now nobody eve gives it a second thought because how could such a little difference like that cause all this trouble. Repeat "little things cause BIG problems"


I will not be satisfied on my end until I can put a gauge before the filter and verify the flow restriction. A problem is not solved until you can prove the cause. Who knows I may find a leaking banjo fitting with the other bolt but I have a fix for that!

 

[MotorSeven]

Wow, Kioti should send you a check for beating thier own engineers to the punch. Outstanding work!