Recently rebuilt my transmission for 621 cat scraper 5s7777 transmission drives good until I really rev up engine transmission gears start slipping i can feel it and engine rpm tells me everything I adjusted the transmission valve spools now some gears feel like there working fine without slippage wat else could an guy look out for So another question is the oil is really foamy and white looking after I run the machine is this normal looks fine after machine stands for an couple hours Read somewhere cat is number 1 for having the worst hydraulic oil Wat r your guys thoughts on this thanks
Sounds like it might be sucking air. Are the suction screen seals & gaskets ok on the transmission & torque converter? How is the hose from the transmission to the transmission pump? What are transmission pressures when at operating temp.
I think and assume my screens r good just cleaned them to make sure I have pressure Guage connected to port on top of the main filter housing if I remember correctly reverse and 1 and 2 r 410 to 440 psi depending on rpm And all the other gears r 280 to 300 so
Did the pump get rebuilt as well? I would still think that if the oil is foaming up it is getting air from somewhere.
No it did not wat does that smaller gear pump do on back of the tranny verses the main pump on bell housing i think
Transmission pump and torque converter scavenge pumps are both mounted at the back of the transmission. The t/c scavenge is above the transmission pump. I haven't seen a 621 for about 25 years, so I'm not overly familiar.