I'm Baaaaaaaack!
So I've got a long winded story today. Last thing I did was replace the trans pump bushings. I guess I shouldn't have done that, because after starting the tranny pump screamed and then stalled the engine.
I didn't realize at the time what actually happened, although it should have been obvious. I guess I didn't want to believe it. Well the pump unseized when I started it back up, but it was still having issues. Every day the oil would drain to the bottom and it would take 2 min to get it's prime back next morning. I didn't notice this all winter because I let it warm up for 20 min in the morning. Well, summer came and I didn't always let it warm up for 2 min. This is when I noticed that it wouldn't shift into gear right away. Now were back to winter and I had time to replace the pump, which I did with a reman pump. When I got the pump I installed the drive shaft and turned it to make sure it was smooth. After putting it in I didn't want seize this one too so I ran the starter but didn't let the engine start. After three times the oil started dropping in the sight glass so I started the engine and let it run. Everything seemed normal except for a slight buzzing sound at med to hi RPM. After 50 hours the pump seized and the shaft driving it broke off.
I replaced this one and ran the engine a little with the new pump and the noise came back. From what I can tell, it seems like the sound starts up after the engine has been running for a few min. This is about the same amount of time it takes for the oil to become aerated.
I forgot to mention between now and last time I posted, I switched to different oil. It was before I removed the first pump and it didn't seem to have a problem with it. Viscosity brand SAE30 and supposedly meets Cat TO-4 specs. Do you guys think this would make a big difference? I will switch back and see what happens.
In the meantime I have a different question. The oil gets aerated when I start the engine, but if I heat the transmission oil up to 180*F, the bubbles go away. Is it possible for the oil to get aerated from being discharged into the transmission through the torque converter inlet relief valve at 200 PSI? The relief valve is supposed to limit the pressure to 130 +/- 10 P3 pressure is around 200 PSI when the oil is 70*F. Torque converter outlet pressure is 150 at 70*F. These pressures are all normal once the oil is at operating temperature.
There is something else I don't understand there are 2 possible torque converter cooler circuits.
126-9584 4YS1-UP
197-5842 4YS705-UP (This one has an oil cooler bypass valve.)
My loader is 4YS1211 and it has the 126-9584 cooler circuit. was the bypass valve an option from the 705 SN# up?