Hi PMP Daddy,
If the suction line is rusted or worn through above the oil level it will not leak oil out of the pin holes.
Bob has given you other good things to check but we used to have trouble with the H & L machines rusting the suction lines through, usually caused by mud, debris etc in the belly guards, especially tip machines as the crud is usually acidic in nature.
Also "if" the rusted section is under the mud etc it may leak out into the mud un-noticed over night and be sucked back in with some of the mud to wreak havoc with the trans. components---saw this many times on various machines in my 43 years at the Dealer on units worn out by dirt ingress.
Hope this helps.
Cheers,
Eddie B.

"edb" wrote:

Hi PMP Daddy,
If the suction line is rusted or worn through above the oil level it will not leak oil out of the pin holes.
Bob has given you other good things to check but we used to have trouble with the H & L machines rusting the suction lines through, usually caused by mud, debris etc in the belly guards, especially tip machines as the crud is usually acidic in nature.
Also "if" the rusted section is under the mud etc it may leak out into the mud un-noticed over night and be sucked back in with some of the mud to wreak havoc with the trans. components---saw this many times on various machines in my 43 years at the Dealer on units worn out by dirt ingress.
Hope this helps.
Cheers,
Eddie B.

Thanks ! Makes great sense, I hadn't thought about it like that.

Havent found suction leak yet, but I am definately getting air in system somehow.It is now much.much worse since I pressure washed the machine.Sounds like "marbles " now. I don't know how the "oil manifold block" that bolts to the left hand side of the transmission is sealed, but if air was getting sucked in via a joint on the inside of the transmission, wouldn't the tranny vent be sucking air in? Also, I see this this "oil manifold" is bolted from the outside of the tranny, why would lid need to come off? Are there additional bolts on the inside? Is there a trick to find out if a joint is sucking air,using some fluid or something. Should I be able to hear it? Thanks!

Hi PMP Daddy,
I think you have found that crud on the suction line and/or the manifold was partially sealing the leak. Now all I can think of is to squirt oil or WD40 on the manifold joints and suction line system and watch for it to disappear in the effected area when pulled in by the suction. If you find a suspect area then you could apply some heavy grease to see if the "marbles" effect lessens.
Or you could lightly pressurise the trans system through the breather and see if the leak shows up by a telltale hiss or bubbles if you spray WD 40 or other light fluid on the suspect areas.
I cannot quite visualise the suction system on the 955H-L as it is probably 15 years since I worked on one, if I recall the suction line goes into the bottom of the Magnetic screen housing and is sealed here by an O ring seal--this is a likely suspect area as the tube and dirt vibrate and wears the seal and housing bore.
Hope this helps.
Cheers,
Eddie B.

I found it, it was the large fitting on top of the magnetic strainer was real loose. I've got the pump back off because it has a small defect at the pressue tap causing a minute leak. Cat said they will replace it, and I wanted to check my o-rings back behind the pump to make sure I wasn't leaking there anyway.But now I'm sure I found it!!!! I really appreciate you guys help, I went back and reread all of your post, and then looked at my D-8 manual that had a basic diagram, and then I came to the conclusion that it had to be on the top hose of the magnetic screen, or inside. When the machine had all the crud the nut felt tight (checked by hand, my mistake) When I just went out , I grabbed the hose, and moved it, and it was real obvious.When I get the 2nd new pump back on, I'll post the outcome.Guys, Thanks so much for all of your help!!

Did you turn the drive gear over yet?
Later Bob

I started to take the hydraulic pump off, and went as far as draining all the oil out, but I decided to recheck the splines.I couldn't feel any ledge on the splines of the gear.I even took the shaft out of the old pump and slid it back and forth , with almost no peceptable wear. The bad pump was an aftermarket one, so maybe they switched it around before. I think it is good ,but since I have the pump off again, I'll recheck it once again.

If you still have the pump you are swaping for another one check inside for any signs of the drive gear digging into the back plate, Just don't want to hear your new pump got ruined in a week.
Later Bob

I tested it out, and the machine works great,I am so thankful! I haven't had the chance to run it hard, and get everything heated up yet, but it is doing much better prssure wise. Around 375 high idle, 350 low idle.The needle on the guage still has a highspeed small magnitude flutter to it , I not sure if I need to be concerned or not.I took the new pump back already, but I may go ahead and do the swap, or at least check the gear out.I am concerned that the fitting that was loose (on top hose of the magnetic strainer) may still have a minute suction leak. (needle flutter?) If this is the case, I think I'll need to take the hydraulic pump off to get to the fitting better, but I'm not sure.

That is a nice pressure drop you have there now. 25PSI on 375 about 8 or 9 % cold.
Later Bob