Barnhart wrote:

This is a picture of a rotorhousing from a 13b. Inside faces are very smooth and everything else
checks out per Bruce's video's specs.  The dark areas are even smooth but doesn't want to clean
off. No ridge. The same dark spot is on the other side of the rotor housing.  My rotor housings
didn't have this and neither did his front rotorhousing. A nicely worn down rotorhousing? What is
it?

Barny
MGDQ

I think it is carbon deposits due to non synthetic oil used
to lube the apex seals. Back in the old days we used to think
this was caused by overheating the rotor housings. Great amount
of labor was expended to die grind cooling ribs inside the
rotor housing water jackets in an attempt to prevent this.

IMHO it just meant the rotor housing surface got hotter than 
the mineral oil break down temp of around 250 to 350 F. Nothing less
than about 500 or 600 degrees is going to affect the composite
steel aluminum rotor housing. The teflon encapsulated silicone
O-rings are good to 500 F.

It forms where it does as the apex seal just jumped over the hump with
reduced contact pressure against the rotor housing surface. This leaves 
a thin film of oil on the rotor housing which then cooks to carbon.
As far as I can tell it does not affect power or fuel consumption.
Probably on the contrary as it eventually leads to better sealing.
You might just try leaving it there :).

All my theory.

IMHO with Mobil One in the oil pan and or two cycle apex seal oil
lube mixed with the gas this will not happen.

What solvents have you tired Barony?
MEK? Lacquer thinner? Gasoline?

Paul Lamar
 
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