955l trans problem

The line going low to the transmission would be the suction side. Actually they are both suction lines going to and from the strainer and on to the transmission pump.
Is the pump seal lip facing out?

Bought new hoses today seemed to fix the sucking air problem but now i only have 75-100psi at filter when warm. I purchased this new pump offline from an aftermarket place could it be bad form running it when it was sucking air?

Well, yes and no. It is possible to damage a pump run dry or not properly primed. Also not flow related but installing a new pump in a worn out splined drive gear can quickly tear up a new splined shaft. Always a question as to integrity of aftermarket pumps, seal installed correctly? seal quality? quality control of the pump body and internals. Also the possibility the pump is ok but you have a leak in the hydraulic system.

Hi Team,
OM is on the ball as is usual with possible internal leakage---been a long time since worked on one of these too.
As Om said worn drive coupling splines can tangle with a new pump splined drive shaft and put excessive end thrust on the pump gear inside the pump causing adhesive wear to take place--metal smearing and tearing.

Fix is:- if a new pump is fitted, measure the old pumps drive spline protrusion from its pump body and measure the protrusion of the new pumps drive spline and shorten the new shaft spline to give around 0.125" clearance in the internal coupling spline wear step ends-- as per a Cat Service Magazine article for all spline drive pumps and motors.

From memory only, I think is same trans. as later D5 which has the filter and a spacer block on one side of the trans. case.
I feel there is a pipe and internal passages inside with "O" Rings--accessible after block is removed ?-- that can fail (bit like one on rear of D6/D7F) and also pipes taking oil to/from the Torque Convertor with "O" Rings that are prone to fail too--these are held in place by a washer affair and one bolt--easy to drop into the case--pack rags under to save red face--also check rag pockets for foreign objects, have seen hair pins fall into a trans from an old apron--sheesh.
If so the pipes here slide into T/C case so as to remove Pressure and Control valve bodies and manifold.
Sorry all a bit hazy after so long without seeing the iron, so to speak, then I would be sure.
Hope this helps.
Cheers,
Eddie B.

I will pull steering pump off next week and check seal on transmission pump. My filter is located remotely on the left side nect to seat. Last fall i removed value body off the top of transmission and replaced all orings under it and on both the tubes. I’ve also pulled the round cover of tip of transmission when shifting it sprays oil is this normal? Ive also checked pump pressure on the pump itself but get same readings as on the filter. My question is what actually is driving the splines that run the transmission pump and the hydraulic pump? Thanks for all the help so far im a novice when it comes to these machines

Pump is gear driven off the front of the torque converter.
Spraying oil from the transmission with cover off is a pretty good indicator there is a clutch leakage problem.
Have you run pressure checks on the transmission?

I have not pressure tested the transmission if it is a clutch leaking is that a big fix?

I have not pressure tested the transmission if it is a clutch leaking is that a big fix?

That's a transmission tear down job to repair.
Do you have pressure test specifications?