On 1/31/2007 3:31:14 PM, "pgbnh" wrote:

But anyway, what's the common wisdom on preheating.

I park my aircraft in an unheated t-hangar in central NY state. Normally, I
plug the Tanis heater in when temps get around 40 degrees and I will further
wrap the cowling and cover the prop with an insulated cover when temps are
forecasted to drop below 25 degrees F or so. Keep in mind, though, that this
is a newly overhauled engine and I am simply preserving my investment.

One morning a couple of months ago I arrived at my t-hangar to discover that
the plug had somehow pulled out of the socket the previous evening and the
engine was at ambient temperature, somewhere around 36 degrees F.

I did not have the time to wait the three hours for the Tanis heater to warm
the block, so I called my mechanic and asked him if it would hurt the engine
to start at that temperature. This mechanic has 40-years in the business, so
I trusted him when he told me that there would be no harm in starting above
freezing. Being that my engine is a turbonormalized 6 cylinder, it was more
important for me to wait until the oil temperature hit 120 degrees before
applying full power. 36 degrees to 120 is a lot of idling.

Anyway, when I asked him what temperature would be a concern, he opined that
when temperatures dip into the upper 20s or lower, preheating becomes
important to engine health.

Then again, I have seen flight school aircraft started without preheat when
temps were around 0 degrees F, but I have also heard of these same engines
having stuck valves and other complications, so I wouldn't use that as a
guideline.

--
Peter