Allison oil pressure

[davidwigler]

Both transmissions are running fine with about a two second delay after shifting, but the mechanical gauges only show about 100 psi in gear. My mechanic helped me change all the cables and adjusted to throw. We also checked the screens and they were perfectly clean. He recommends adding 1/2 quart of Lucas oil treatment to each transmission to help with oil pressure. Comments?

 

[oscarvan]

I think the delay is "characteristic to the device". Either that or both of mine are malfunctioning too.

 

[Pascal]

Is the delay going in forward and not reverse? Typical sign of low oil level.

 

[oscarvan]

Is the delay going in forward and not reverse? Typical sign of low oil level.

In my case both. And oil level is correct. Maybe it closer to 1 second.

 

[KPTIM]

The delay is normal, and yes the pressure is low.
Do not add anything to the oil to fix the pressure.
Have you or your mechanic tried to adjust the pressure?
There is a pressure regulator adjustment on the cam driven hydraulic pump.
Use a mechanical gauge connected to the transmission to monitor the pressure and eliminate any error that the electrical gauges may have while setting/adjusting the pressure.

 

[rustybucket]

Before I adjusted anything I'd want to verify pressure with a mechanical gauge. Also, post the model of the gears, that may help in someone helping you troubleshoot.

You say you cleaned the screen, did you also change the filter? How old is the oil? Are you certain its the right viscosity? How are you checking level? Engine running? In gear or out of gear?

Also, maybe check the time delay with a stop watch. 2 seconds would feel like a LOOOONNNGGG time. In the heat of the moment when shifting 1 sec or even a half a sec can feel like a long time but is completely normal.

 

[Scarlett]

Check both sets of gauges, my fly bridge gauges are mechanical and read higher than my lower helm gauges, or as others have suggested make sure you have a mechanical gauge to check them for sure. I also agree the delay is normal. John

 

[Pascal]

It s been a while since I ve had Alisons but mines never had a delay. They always engaged pretty much instantly

Another source of issues is the gasket on the screen housing. I don’t recall the details but I remember that if the gasket isn’t in perfect shape and the three bolts evenly torqued the pump will suck air crating low pressure and delays

 

[racclarkson@gmail.com]

Then look for frothy oil after running.

 

[SEVEN]

My gauges read close to 200 and I knew it was wrong. I added mechanical gauges directly to the transmission and both read 125, that’s where they are supposed to be. Check them with mechanical gauge first before going deep

 

[davidwigler]

Same delay and pressure in forward and reverse. I didn’t use a stopwatch so maybe I exaggerated. 100 psi is from a mechanical gauge in the engine rooms. No frothy oil. Clean 40 weight NAPPA oil just like the engines. External filters and oil were changed about 300 hours ago and oil looks new. New gaskets on the screen fitting and bolts are tight.

Both transmissions are reading 100 psi. I guess it’s time to try adjusting the pressure. I’ll get the manual out and read it. Any suggestions? Clockwise to increase?