>
>2. It is the air cooled engines that can be damaged by the engine
>braking.  This is due to the engine coming to very high temps while going
>up a mountain pass, and then the rapid cool down that comes with the
>engine braking going down the other side of the pass causes the metals in
>the engine to contract rapidly, mainly the cylinder liners cooling and
>contracting faster than the pistons, causing excessive wear and tear on
>the pistons and liners.  This is where the rumor about engine braking
>being bad for your engine started.  The water cooled engines have the
>water jackets and thermostats to maintain engine temp., therefore avoiding
>the rapid cool down problems.

This is a big problem with air cooled aircraft engines. Some planes even
have air brakes to help alleviate it.

Joshua Van Tol -- jjvantol@lear.csp.ee.memphis.edu
[text/enriched]

<excerpt>

2. It is the air cooled engines that can be damaged by the engine
braking.  This is due to the engine coming to very high temps while
going up a mountain pass, and then the rapid cool down that comes with
the engine braking going down the other side of the pass causes the
metals in the engine to contract rapidly, mainly the cylinder liners
cooling and contracting faster than the pistons, causing excessive wear
and tear on the pistons and liners.  This is where the rumor about
engine braking being bad for your engine started.  The water cooled
engines have the water jackets and thermostats to maintain engine
temp., therefore avoiding the rapid cool down problems.

</excerpt>

This is a big problem with air cooled aircraft engines. Some planes
even have air brakes to help alleviate it.

Joshua Van Tol -- jjvantol@lear.csp.ee.memphis.edu