The TCM #654580 "G" cooler will fit the "N".  That cooler has at least 6 TCM part numbers and has been used for over 20 years on many different engines including the TSIO-550 which runs fairly cool oil temperatures from what I understand.  I'm sure the reason all Continental powered Lancairs have an oil door is because the "G" cooler works too well.

 

That's not true for many of the TCM #654585 "N" coolers.  My oil door is on the shelf.  I get 200-205 oil temps in cruise when my CHT's are around 340-360.  Interestingly, my oil temp was right around 180 for the first 35 hours and then shot up 25 degrees.  My guess is a small internal leak developed that caused some portion of the oil to bypass the cooling fins.  Some coolers leak worse than others, some don't leak at all.

 

This theory is based on several conversations with an oil cooler engineer who was reverse engineering the "N" cooler for PMA approval.  He said the way the coolers are assembled left a lot to be desired and their own design would eliminate the potential weakness.

 

I know of at least one ES guy who was running high oil temps and got a replacement cooler from TCM and is running at 180 now.  Another ES guy who bought a Positech and is running at 180 now.  Another ES guy has gone through a couple coolers with no improvement.  TCM won't change models of coolers on a warranty, Ron G. is right, they would have to create a whole new engine model to do that, not going to happen.

 

Mike Easley