4620 3 point / lift problem

[Ireland.29]

hoping some folks here can help with a breakdown i got today - i put the 4620 to work for first time, all went well but while ago the 3 point lift stopped working completely and the 3 position dept control lever jammed at same time.. i managed to get lever moving again but still no lift - the rockshaft? hosing where lift control lever connects into seems to be making a strange sound? all other hydraulics working ok

 

[thurlow]

I'd suggest a problem in the rockshaft control valve housing; cam follower may be off track. You MAY be able to identify problem by removing plug in rear (1/2 inch drive breaker bar) and looking inside while shining a light from above thru filler opening (I found it helps to remove pipe nipple). A service manual would be a big help.

 

[Ireland.29]

thanks.. i have the manual but im still a little lost, its strange the way it stopped working out of the blue! does the noise coming from rockshaft valve housing tell anything?

 

[Tx Jim]

The noise and failure to operate probably indicates blown rockshaft valve control o-rings. Look in the hole that thurlow referred to and see if you can see spraying oil with 3pt lever in raised position and engine running.

 

[Ireland.29]

thanks tx jim, would it be normal for orings to fail suddenly like that? i looked at tractor while ago along with my parts / service manual but cant locate the nut you describe?

 

[Tx Jim]

The nut(bung plug) is located very close to the serial number tag,to the right and above the pto shaft. What task were you performing with the 3pt??????

 

[Ireland.29]

thanks I will take another look tomorrow morning.. should oil escape from there when I open it up? I had a 3m power harrow on the 3point.. didnt seem to stress the old girl too much but the lift control lever was getting a lot of use lifting the harrow at each headland etc

 

[Tx Jim]

No oil should spray out the hole with engine running.

 

[Ireland.29]

still having no luck locating this plug / bung.. the only possibility is it could be the place where there is a return male hdy fitting going back into transmission.. could this have been screwed in in place of this plug?

 

[Tx Jim]

The plug is to the right of the 3pt centerlink attaching bracket.

Part Number: R27483
Part Price: 8.50 USD
Description: FITTING PLUG
Weight 0.20 LBS 0.09 Kg
Thread Size 1.125 IN
TPI (Threads Per Inch) 12
Thread Length 0.626 IN
Length 0.811 IN
Square Size 0.511 IN
Diameter 1.375 IN

 

[Ireland.29]

excellent, thanks for that TX Jim,yep my 4620 has a male hyd end screwed int that hole, prob meant as a return oil line.. I'll remove that soon as I can and see if oil sprays out with engine running and lever raised