f9 runs hot in forward direction

[southern pacific]

Hi !  I recently received my Union Pacific (soon to be Souther Pacific) standard  Bachmann F-9 diesel.  after and during the break-in and still, the engine needs a "60" on my m.r.c. power pack, this makes the engine run very hot, but it still runs smooth that way. in reverse, it runs at "45" and stays totally cool. I took it apart, cleaned off the extra grease, checked for binding gears, drivetrain slack and motor for any debris and all checked out. re-assmbly, same thing !  since F-9's or any F units rarely ran solo, especially on the espee, i run it in multiple with dummies, right now it's pushing a PA-1 which is pushing a FM-C-liner ( i know s.p. didn't have these but it looks good painted grey and red) and it's pulling seven daylight cars. I really don't want to send this engine back, but i was wondering if i overlooked something that might cause this ?

[seadowns]

Well, lets give it a try:

Did you clean out the motor correctly? Even if the engine is new they could have dry motor shaft bearings and a tiny drop on each can probably cure it.
The first thing I would do in such a case is interchanging the trucks, the leading truck to the back and vice versa.Then check the lokies behavior.
Did you clean out all the gunky factory grease out off the trucks?
If you put the trucks on track do they roll absolute free or is one sluggish?

Regards
Mathi