How to check the ALLISON transmission fluid level.......... from the GM manual
COLD CHECK:Truck in PARK, engine at idle 500-800rpm
Run engine for one minute, apply brake and shift to Drive, then back to Neutral, then to Reverse, this fills the hydraulic system
Put trans in Park and with the engine idling, pull trans stick and wipe clean, check fluid level twice, should be in the "COLD CHECK" band. If above COLD CHECK band when cold, drain to proper level.
A transmission sump temp of (71C-93C)160F-200F is considered HOT. Or you can use converter out temp of ( 82C-104C ) 180F-220F.
Use same sequence as above only this time with fluid level in the "HOT RUN" band.
The HOT RUN band represents APPROX 1.0 ltr or 1.06 qts at normal operating sump temperature. Add or drain fluid to put it in the HOT RUN band.
Trans fluid must be changed when there is evidence of dirt or a high temperature condition (usually above 240, if it does go above 240, good idea to change it ASAP...cheaper than a new trans). High temp causes the fluid to break down and be discolored and/or have a strong odor. If you find evidence of coolant in the fluid, system MUST be drained and completely flushed and of course you want to fix the source of the contamination before operating. ONCE YOU GET COOLANT IN CONTACT WITH THE CLUTCHES, count on a rebuild, this happened to a friend 6 months ago....complete rebuild.
Hope this helps.
07 LBZ 4X4 CrewCab/SB
Last edited by BIOTEC; 02-20-2010 at 01:25 PM.