430 Loader bucket won't stay up.

[jdmar]

430 Loader bucket won\'t stay up.

OK OK, I know the jokes may get goin here...
My 430 Loader bucket (on a gear 4300) will tilt up/back but will not stay up even under its own empty weight. It will tip forward with pressure and hold up the tractor (e.g. when using backhoe). It will also still lift a full load of dirt/stone/sandstone blocks, etc. But after tilting it it starts to drift down as soon as I let the scv lever go forward

I have to start tracing the problem but thought I would post here in case others have had the same problem. I doubt the cylinder is bad since the tractor has only 450 hours and it will still lift a load without difficulty. I suspect it is in the SCV lever. I here these levers are a "weak/problem point" on these tractors. Once before the lever wouldn't re-center so I had to adjust/tighten some nuts on the valve ends (sorry I forget the details of what I did). But when that was occurring I heard a "hiss" as hydraulic fluid snuck through a barely open valve. No "hiss" now.

Any Ideas would be appreciated and may save me hours of tracing the problem. ? air in the line??

thanks ahead of time for everyone's help.
Peter

 

[Jim_Fisher]

Re: 430 Loader bucket won\'t stay up.

jdmar,

</font><font color="blue" class="small">( My 430 Loader bucket (on a gear 4300) will tilt up/back but will not stay up even under its own empty weight. It will tip forward with pressure and hold up the tractor (e.g. when using backhoe). It will also still lift a full load of dirt/stone/sandstone blocks, etc. But after tilting it it starts to drift down as soon as I let the scv lever go forward )</font>

Deere has some information on their web site that I found helpful. Tips & Troubleshooting

I had to rebuild the cylinders on my 430 loader at around 500 hours. A curl cylinder failed first with an internal leak followed shortly by one of the boom cylinders.

An o ring that acts as a tensioner on the piston ring failed in both cases. The new o ring appears to be made of a different material than the one that it replaced.

Deere gives a detailed diagnostic procedure in the link above.

For a quick - down and dirty - diagnosis, switch the hydraulic line pairs at the quick connects in front of the SCV. That should tell you if the problem is in the valve or the cylinder, assuming that the problem is limited to the curl.

 

[jdmar]

Re: 430 Loader bucket won\'t stay up.

I printed that off the Deere websight...thanks a lot for the link. Sadly today I can't check since I have no hydraulic fluid in the tractor. I was changing all the fluids before winter and when I removed the suction screen it had worn through at the far end. It is only a $26 part but wont be in for a couple days. So now I have a "dead" tractor in the garage. hhmmmm maybe a piece of that screen found its way to my SCV ...?????

I'll let you know what happens. By the way, how hard was it to remove and rebuild the SCV??? Just wandering if I want to do it myself or take it to the dealer. Or did you just rebuild the cylinders on the loader itself?

Peter

 

[Jim_Fisher]

Re: 430 Loader bucket won\'t stay up.

Peter,

</font><font color="blue" class="small">( By the way, how hard was it to remove and rebuild the SCV??? Just wandering if I want to do it myself or take it to the dealer. Or did you just rebuild the cylinders on the loader itself? )</font>

I rebuilt the loader cylinders. The SCV didn't fail.


Here's a link to another thread about the same problem. 4300 loader thread

 

[BrentB]

Re: 430 Loader bucket won\'t stay up.

I had to have both lift cylindes of my 420 loader rebuilt before hitting 200 hours on my 4200. In my case the loader would drift down (two separate occasions). I'm convinced there are no line relief valves in the loader circuit, and so various combinations of lifting, tilting, and tractor motion can induce higher than system pressures in the cylinder lines.
The result is a blown hyd cyl seal which lets oil leak past one side and to the other.

As a point of interest, cylinders with a blown piston cylinder should eventually stop drifting if the load is trying to push the cylinder closed ( such as a lift cyl) but will allow a tilt cyl to fully extend. This is due to the differential areas on the head end and rod end of the cylinder. Since there is no additional oil coming in or leaving the cylinder, it eventually compresses on both sides of the piston and locks it up. An extending cylinder can cause the oil to cavitate on the non-rod end, and so the cyl keeps traveling out. Okay... maybe this is only interesting to me! /forums/images/graemlins/crazy.gif

 

[Jim_Fisher]

Re: 430 Loader bucket won\'t stay up.

Brent,

</font><font color="blue" class="small">( As a point of interest, cylinders with a blown piston cylinder should eventually stop drifting if the load is trying to push the cylinder closed ( such as a lift cyl) but will allow a tilt cyl to fully extend. )</font>

Mine weren't blown. The piston ring in mine is sort of a quad ring with the piston side rounded. In the rounded part lives and o ring, which serves to tension the piston ring against the cylinder. The o ring is what failed.

The curl side went first, pretty good power but immediate leak down. I found about one third of the o ring missing when I tore it down.

The boom cylinder was interesting. Feather the SCV up and the boom dropped very slowly. Pull back on the joy stick a bit more and the boom went up as expected.

Cycle the loader all the way up and the problem might go away for a while. When I tore it down, I found a break in the o ring but no missing pieces. I suspect that the piston ring was shifting and distorting.

 

[jdmar]

Re: 430 Loader bucket won\'t stay up.

Thank you, Thank you, Thank you.

I got my tranny fluid suction screen in today so I was able to get the tractor goin again. I re-attached the loader then switched the lines (red, green yellow, etc). The bucket still drifts down even though it is now controlled by different portion of the SCV. So I guess my bucket tilt/curl cylinder(s) is/are bad. I may rebuild them myself but first I'll find out how the dealer wants to do the job. Still seems strange that several of us have had this problem. I may also post a "warning" to others about my suction screen problem once I can get a phot of it.

Thanks again for all your help..hopefully I can get it all fixed soon.

Peter