D6N blade drop issue

[powerjoke]

In addition to the other thread about my new to me dozer and the u/c fiasco I thought I would start this thread to help with some ideas,

This AKM machine has a little bit of a blade drop issue, it'll drop 4" in 15 seconds and if you try to pick up the machine it will not raise the tracks off the ground at an idle, as soon as you full rev the machine it lifts the machine like it should however as soon as you let off the control lever it slams the machine down on the ground as if you hit float..

Have no leaking cyl to speak of (one has a gland seal wet but not streaming or dripping fluid), has no leaking lines that I can find, I am wondering if it is in the valve body or if it needs calibrated I believe it's elec/hydro (has the thumb rocker for blade angle) as it is an ARO ready machine and I believe it has had a gps system on it at one time as there is a missing "gps on-off" switch on the dash (not a factory decal/sticker)

My thoughts are that maybe the ARO system is somehow not holding the blade ?.... It's either that or valve body is leaking internally, I have not had the chance to cap off lines and try to isolate it but I can't see how that would really help narrow anything down as there is no visible leaks we know the valve body is passing fluid right??

If it does infact take calibration for the blade control could someone please email me procedure

The machine just came in from TT&E-inc and was not disclosed to have this issue (or any of the other problems it has for that matter) but they told me they would not help get the machine repaired to what it was represented as when I bought it (sight unseen) and that I was on my own send me a pm if you really want to know what I think about Henry and Scott

Pj

 

[mitch504]

Pj, I already know what you think about them, without ever discussing it other than reading your posts. I'm sorry you got such a $€@t sandwich. I would be looking at sending the machine, if you really think they'll just give you your money back. Then turn a lawyer loose on getting your shipping back. Even if he got $2000 and you got $2000, getting rid of this thing for $2000 might be the best bargain they ever gave anybody.

Mitch

 

[powerjoke]

Lol you might be right Mitch

Pj

 

[vapor300]

I'd say its in the valves, was running one awhile back that if you were in a hard push and got more dirt on the right side, the blade would starting folding in. Had to be holding the thumb switch to the left to keep it from folding in.

 

[overworked]

Lift cyl packing? Easyest to check. Plug off one cyl at a time.

 

[powerjoke]

Can someone get me the part number to the svc manual for the hydraulics or send me a few pages that I need please

 

[willie59]

I don't know a thing about a D6N, nor do I have an access to info. I wonder If Nige might be able to help on this one?

 

[Nige]

I can send you the hydraulic schematic if you PM a full Serial Number & your e-mail address.

Regarding troubleshooting the hydraulic system there's probably something in the system on that also. Let me know by PM. It make take a couple of days to download all the available material.

 

[powerjoke]

:drinkup

 

[willie59]

Da-yum, looks like I rubbed the bottle and got the genie out of it. :drinkup

 

[mikebramel]

Did you get this figured out

 

[powerjoke]

My boys have been breaking stuff faster than I can fix it but it is coming in the shop first of the week hopefully I'll know something by then

Pj

 

[HSV127]

You may have already done it but I would check all hydraulic system filters/suction strainers for filings as I had a similar problem on my D6 (though mine was an H not an N) that turned out to be slightly bent lift ram spears causing the pistons to scrape the inside of the bores sending filings on a tour of the hydraulic system. Hope this isn't the case for you though!

 

[nowing75]

Did you get your D6 and fixed I had the same problem HSV had with the bad cylinder causing metal in the system to stick the spool valve now I got it fixed but the float position does not work I'm still troubleshooting exactly how that system is set up.

 

[Mark10]

We had a problem with a cat d6n prefix DJY, the blade was turning to the left it's self after thinking the seals were away and had the 2 rams resealed it turned out to be the blade lever that was goosed.

 

[powerjoke]

I haven't had time to mess with it to be honest, the operator that runs it daily deals with it and doesn't complain, trims raids and parking lots with it and does a good job, he's learned to deal with it. With all that being said I am still going to dig into it but just haven't had the time it's worked damn near every day for the last few months and doesn't look like it's coming into the shop anytime soon again.

On a side note mark 10 I wish it was that simple this one is a pilot control machine, has the funny looking thumb rocker for the blade angle

Pj

 

[Mountainmover]

WOW. We had a d6n borrowed/rented on a local government job last fall. The EXACT SAME THING happened to the d6n we were using. It would do it sometimes...sometimes not. Never got it figured out before it left for some other job.
It would be stuck doing it and we would have to park it. Then, you would mess with it and it would stop and not do it for days...then wham....again!

It began while pushing loose fill dirt dumped by trucks. But previously....against my approval or judgement....the guys on the job were pushing a 637 scraper with the dozer in very soft silty material. I kinda had a theory that a 6 way blade dozer such as that couldnt handle pushing a heavy pan like that....because the scraper might raise or lower the bowl and manipulate the blade suddenly...or catch a rock...or well...you know.....as I assumed it would cause cylinder damage and contaminate the valves, screen, and such..... A local mechanic scoffed at my theory saying the filter would catch it all....but in my mind...I thought...what if the pieces went back through and stuck somewhere AFTER the filter location? But I gave up. I need to get up with the dozer owner and find out if he ever figured it out or just left it alone.....

I recall watching the mechanic mess with the joystick control and valves.....then he said he saw a piece of purple looking o-ring in the spool valve of blade and thought that might fix it...yet it did not....

I had a cat d3b that had a weird issue like this in the angle circuit of the blade hydro system. it would lock up....hang...or whatever at random times. I kept investigating and spending money until i figured out it was a bad hose that was separated internally and the flap inside the hose acted as a VALVE! Flipping back and forth at will.......sticking or not sticking....depending on many factors such as hydro temp..or pressure....

Make sense? IDK.....lol