2005 RTV 900 charge pump with low pressure

N

Nomansland

New member
I bought this RTV knowing it had transmission issues. The swash plate for the HST was in the bed along with a new thrust bearing and the old one that was blown up. They had lost the guide for the swash plate so after getting a new one, I reassembled it and started checking the pressures.
No pressure on either the forward or reverse high side at all. I then checked the pressure for the charge pump and it read around 45#, should be 75-104# according to my WSM.
So to remove any doubt I ordered a new charge pump and pressure relieve spring even though I couldn't tell that anything was wrong with the ones it had originally.
After installing the new pump and spring, I checked and now I only have about 15# pressure. Any ideas????
 
bordercollie

bordercollie

Gold Site Supporter
Gold Site Supporter
.. Were they Kubota filters with kubota hydraulic fluid in the transmission ? My RTV's transmission was always happiest with sudt. I had the hyd dump bed but rarely used it but did have over 4,200 hours on it when I sold it to buy my '12 and then the same with it. .
 
A

aurthuritis

Well-known member
Site Supporter
there is a suction hose to the charge pump that can collapse or separate internally that can cause issues with charge pressure. and of course the Kubota brand filters and fluid can and do make a huge difference.
 
N

Nomansland

New member
Kubota filters and UDT2 fluid. I wasn't aware of the internal suction hose. I'll check into it this evening. Thanks
 
N

Nomansland

New member
Sure enough, one of the hoses had a split in it. Changed it and now back to 40 -45#. It even once went to 50# but dropped back to 40 -45#.
Any other ideas because I'm at a lose.
 
A

aurthuritis

Well-known member
Site Supporter
probably a little piece of degraded hose in a bypass valve. you could try running it around a little bit to see if the filter would catch it? did you cut the old filter to see what was in it?
 
N

Nomansland

New member
It doesn't move at all. The way I understand it, the charge pump pressure activates the servo which in turn moves the swash plate for the HST therefore creating power to the stationary motor and wheels. Is this not correct?
 
A

aurthuritis

Well-known member
Site Supporter
Nomansland said:
It doesn't move at all. The way I understand it, the charge pump pressure activates the servo which in turn moves the swash plate for the HST therefore creating power to the stationary motor and wheels. Is this not correct?
Click to expand...

yes that is pretty much how it works. but i think the servo should work a little with 45 lbs pressure. has the servo centering screw been messed with?
 
N

Nomansland

New member
Ok, the filters are correct. From all indications from the dirt and such, nobody has messed with the servo adjustment.
I'm having some pressure gauge issues so I'm going to have to find another one and continue on with it.
 
A

aurthuritis

Well-known member
Site Supporter
your servo piston could be stuck?? i would sort out the pressure gauge before i advanced. you either have a leak internally or a restriction in the supply. your big jump in pressure when you corrected the suction hose makes me think it is a supply problem. get the charge pressure corrected and then you can advance to the servo if it is even an issue?
 
N

Nomansland

New member
Ok, I finally received my pressure gauge kit, Amazon failed miserably on this. When I start it up and let it idol, it stays at 55#. When I rev up the engine, it will go to 80-85# and then immediately fall to about 20# and stay there. Any ideas?
 
N

Nomansland

New member
As far as I can see, the hose isn't collapsing. I guess I need to take the servo apart and see if there's an issue there.
 
You must log in or register to reply here.
Top