Who has an 8.3 Liter Cummins coupled with a 6 speed Allison Transmission?

[Jim]

I was running about 65mph for 4 hours and pulled into a rest area. About the time I got parked, I got a transmission is "hot" symbol on the display. The actual temp read 201* I let it cool down and took back off. Kept it at 55mph. Temp ran back up the 201*, stayed there for a few minutes, and then dropped back to 189*. It appears that one the temp hits 201*, a fan comes on and cools the fluid down to 189*-190* Never saw the "hot" symbol again.

Is this normal?

 

[RKins]

Sounds like it is operating correctly. Do you have a side radiator? Mine has a hydraulically driven fan that comes on when needed to cool the fluid down.

 

[Jim]

No, I do not have a side mounted radiator.

Yesterday was one of those days where too many things went wrong. Or I thought they were going wrong anyway. Turns out that everything was working exactly as it should but I didn't know it. So yeah, a good learning day.

Do you happen to know what temp your Allison runs at 65mph? Mine it turns out, is between 195-200. Which I thought was high but apparently it likes it there.

Thanks for the response!

 

[Neal]

When on hills the temp may rise (i.e. as the engine is working harder) and downshifting will engage a cooling fan (I think it is) that will bring the temp down.

 

[Buly]

If it becomes a problem and it bothers you, a transmission cooler could be cure?

 

[Jim]

I'm scheduled for service on Thursday but the tech said that the Allison in my coach should operate between 185 - 230, which sounds kind of high but what do I know. Anyway, I don't know when the last time this rig had transmission service so I'll error on the safe side and have all the fluids and filters changed.

 

[Neemer]

Jim, I have found that the temps of my engine and transmission are usually very similar. Exceptions may be mountainous driving, but otherwise, they pretty closely mirror each other.

 

[Jim]

Jim, I have found that the temps of my engine and transmission are usually very similar. Exceptions may be mountainous driving, but otherwise, they pretty closely mirror each other.

Thanks Ed, good to know!

 

[RKins]

Mine too.