hydraulic pressure

kennyl123 · May 31, 2014

hi guys, I have a ford 2000 3 cyl deisel and I have rebuilt hydraulic pump I replaced all intake ball valves and cages and springs all out feed ball valves cages and springs put new valve plate and replaced all gaskets. After doing all this it still don't have enough pressure. I can remove bleeder plug and hold my finger over it and it won't even blow my finger off the hole. I have rebuilt top cover and put a new cylinder in. a lot of money and still no lift. I removed lift cover and turned engine over and hydro fluid comes up infeed pipe but slowly. Can you help?!!!!!

Soundguy · May 31, 2014

remember. pressure is the opposition to flow.

your finger over that bleed hole means zilch if there is another path for the oil to go... like straight to sump thru the unloader valve.

if you have flow and you believe the pump will be CAPABLE of making pressure. yet you have no lift.. then the next 3 things to look at are:

relief valve: it can be blown open meaning no pressure will build in the system

backpressure valve bad: means the unloading valve is dead and your unloader will never operate to divert flow to the cyl... backpressure valve usualy provides about 40 or so psi to keep the unlaoder valve responsive. or at least the prior model systems do that. and that 2000 is similar design.

unload valve: these can stick int he unload position.. and all yer oil dumps to sump just as if you had the 3pt handle int he down position...

kennyl123 · May 31, 2014

Thanks SoundGuy It must be the back pressure valve because I put a new unload valve and relief valve. I will order one and try that and get back to you again many thanks for quick reply Kenny