Go BottomBucket Cylinder Leakdown different problem
 | Mike H.
Join Date: Posts: 1 
|
2003-07-21 59918
I am also having a leakdown problem on my 420 loader but in my case even when the tractor is running the bucket cyliners leak down at a fairly rapid rate. I never had a problem before but I have been doing a lot of digging with it and I guess I have partially blown out one of the seals (internally). My question is whether the cause could be isolated to the cylinders themselves or the SCV. I guess there are some overload valves as well which could also be the cause of the problem. Are these located in the cylinders themselves or are they part of the SCV control? Thanks for the help and let me know if you need more info.
Reply to |
Quote Reply |
Add PhotoBucket Cylinder Leakdown different problem
| BrentB
Join Date: Jul 2003 Posts: 21 Illinois
|
2003-07-21 59919
do a search for the thread called "Loader Leakdown". There
you'll find lots of info on how to test to see which cylinder is leaking, or if it even is the cylinder.
That said, I'll bet it is one of the cylinders. When the
dealer fixed my cyl, they saw bits of rust in the barrel,
but went ahead and put it back together. Later I got to
thinking about it, and was mad at myself for not making them
hone the rust out. I also suspect the cylinder got rusty
while in the factory or being shipped, since it sure won't
rust when full of oil. be sure to have them check it.
Brent ....
Reply to |
Quote Reply |
Add PhotoBucket Cylinder Leakdown different problem
| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
|
2003-07-22 59924
Whether the tractor is running or not makes very little difference to loader leak-down whether it's in the cylinders or the valve. Safety relief valves for the cylinders and lines almost certainly are part of the loader valve. They can be isolated from the cylinders by disconnecting the hoses (very easy if they use quick-connects).
The best test for cylinder leaks is to fully extend them, open the exhaust-side line and then feed pressure to the other side. It can be done on the tractor and the advantage is that max pressure is applied to the seals. Oil will come out the open hose if the cylinder seals leak.
Just disconnecting quick connect cylinder lines when the loader is up with a load and waiting to see if leaks down is another possibility. Pressures the seals have to withstand won't be as high. In addition, the bucket also probably would have to be jacked up just right to relieve line pressures so quick-connects can be easily reconnected.
....
Reply to |
Quote Reply |
Add PhotoBucket Cylinder Leakdown different problem
| BrentB
Join Date: Jul 2003 Posts: 21 Illinois
|
2003-08-01 60686
Last year the right 420 loader lift cylinder blew the piston seal, and yesterday the left cylinder seal blew while I was lifting some landscape rocks. I can't understand why it failed with less than 130 hours on the 1999 model 4200 tractor.
I looked at the hyd schematic in the service manual and
don't see any signs of a line relief (There is of course the
system relief valve). Does anyone know for sure that there
is a line relief?
Brent ....
Reply to |
Quote Reply |
Add PhotoBucket Cylinder Leakdown different problem
| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
|
2003-08-02 60739
Wish I could help with specifics but I'd be surprised if if didn't have circuit reliefs. They usually are under fairly large hex-head caps on each control valve section. Many after-market valve assemblies have their own main reliefs as well but I think it's fairly common that factory valves don't have main reliefs since they're intended for tractors that already have a system relief.
I don't think this is a normal problem. I'm curious about the operation when the problem was first noticed. For example, did the loader just quit lifting during a heavy lift? Did it just start leaking down when no control valve was active or during some other condition? I'm also curious if you can hear a relief valve opening for example when the bucket is curled to max and the control valve held open? I'm also curious if the 3ph may have been in lift mode when the loader was used.
....
Reply to |
Quote Reply |
Add Photo
Go Top
Share This