Jump to content

Heat from Motor to transmission


Recommended Posts

Back ground,

97 1100rt 75,500 miles

Changed the gear oil in the transmission and it came out the color of coffee. 6000 miles since last change. No chunks or other metal peices. Just a light golden haze. Also, two very road burning rides of 900 miles each.


Can heat from the motor cause overheating of the oil? Or riding hard?


Thanks for the wisdom of the collective!


Link to comment

That's not heat but rather a seal failure. Often times a failing bearing releasing it's internal grease. May be time for a internal tranny look see (aka teardown). :P

Link to comment

Your syndrome has a name, 'chocolate-colored gear oil.' It's impossible to diagnose your transmission from a distance of course but usually this is not due to heat but a discoloration of the oil caused by the failure of a seal in the sealed roller bearings in the transmission (the grease normally sealed inside leaks out and discolors the gear oil.) The most common cause of this is a failing rear input shaft bearing, a recurrant issue with the M97 oilhead transmission.


Again, nothing but conjecture at this point. Send an oil sample into Blackstone for analysis, that will tell the story. High chromium and iron = bye bye bearing. If you've already contaminated your oil (by draining it into a dirty oil pan for instance) then re-fill the transmission and run it for a few thousand miles, then sample that.

Link to comment


This topic is now archived and is closed to further replies.

  • Create New...