Hello. I have a dx40/tc40d with a pedal problem. When the tractor has been run awhile and warmed up. The pedals loose almost all of the pressure both forward and reverse. Everything is fine when cold. I just changed filters and proper fluids. Any ideas or where to start? Thank you,Griz.
A lot of hydraulic pump problems are simply problems in the suction line to the hydraulic pump. They either starve the pump for fluid, or introduce air into the hydraulic fluid
If you have a good shop available I've no problem with taking it in. But if you want, first check your operator manual to see if you have cleanable pre-filter before the hydraulic filter. If you do, the operator's manual will talk about cleaning it because it is an owner maintenance kind of thing.
So I don't know if yours does, but lots of tractors have a cleanable suction filter in the hydraulic system. Someone here ought to know. It is common for that pre-filter to be a simple stainless steel screen under a plate somewhere on the bottom of the transmission. Often it is where the suction line to the pump - the line that feeds fluid to the pump - connects to the sump of the transmission. This crud filter's jobjob is to stop the large pieces of crud. Particularly if you ever had water in the hydraulic fluid (milky fluid) then that pre-filter will get plugged with goo and particles. You simply take it out and clean it up then reinstall.....if it has one at all.
The other problem that will cause a pump to have less pressure when it warms up is that sometimes a small amount of air is being sucked into that feed line between the sump and the pump. That particularly happens at the ends of the feed line or where it makes a sudden bend. It's a known problem when the suction line is a hard rubber hose instead of a metal tube.
That is a bit harder one to diagnose but you sometimes find can find it because the pinhole leak that is sucking air when the tractor is running will then leak a little bit of oil out - but it can only leak when the motor is NOT running. It only leaks a tiny amount of oil overnight, and it only does it when the tractor is sitting, not running.
Those are the first two things a good tech is going to check, and it may well be worth it to you to have him do the checking - if you have a shop you trust. And I hope you do.
When I was a mechanic I learned to look first for the simple things. Then run some tests. And then sit down to think about a diagnosis.
good luck,
rScotty
