Hard Starting Cold Continental Engines

On 29 Nov 2005 05:55:17 -0800, "M.E. Borner"
wrote:

throttle open 1/4 inch
mixture full rich
electric fuel pump/prime on
wait a few seconds (2 at the most)
crank

Definitely not enuff fuel for a cold start.

In warm weather it starts right away. Colder weather takes 4-5 seconds
of cranking before it starts. Cold weather takes major cranking and no
fuel pump after the first attempt. Sometimes I get it going and
sometimes I don't. Both engines are very difficult and uncertain,
although the right engine is much more cooperative than the left.

What does "the book" say for a cold start?

I learned to verify power and mixture levers aft, boost pump on, power
& mixture full forward for 2-3 (or 3-4) seconds, pull back. Crack the
throttle, crank the engine, apply mixture lever as needed once the
engine starts running. Was taught never to crank an RSA engine with
the mixture out of ICO.

If it's colder, the levers need to stay ahead longer. The trick is to
get it rich enuff to fire, but not excessively rich. If it doesn't
fire almost immediately, or fires and dies, you just need to add a
little more fuel. If you flood it, you're screwed.

You just need to figure out how much fuel your particular pair of
engines need to start with varying OAT's

TC

wrote in message
You just need to figure out how much fuel your particular pair of
engines need to start with varying OAT's

TC

TC makes a very important point that is often overlooked when training
pilots. I usually start by asking a student what they think happens with
the density altitude is when it's cold, then I ask them what that does to
their fuel/air mixture. Next question is, if you've got more air, don't you
need more fuel? It's amazing how many show surprise. Same theory, opposite
actions for hot temps and hot starts.

Jim

M.E. Borner wrote:

My un-preheated cold weather/cold engine starting technique is very
similar to my warm weather/cold engine technique

You might want to consider investing a (relatively) small amount of
money in a Tanis heating system. The cost of overhauling those two
engines, including removal, shipping, and reinstallation, would get you
a good way towards buying a house in some of the poorer states, so a
couple of thousand (including labour) for a heating system and
insulated covers would be a wise investment.

If you don't have access to electricity, is there a Herman Nelson or
similar force-air preheater somewhere on your field? If not, perhaps
there are small, portable, propane-powered forced-air heaters you could
buy and bring out with you (I haven't investigated this, since I keep
my plane at a major airport with lots of services).

When you're visiting a remote airport, you can always cover the engines
after a flight -- they should stay warm for quite a few hours under an
insulated cover.

I have to admit that I've cold-started the O-320 on my Warrior down to
-15 degC (with a *lot* of priming), but I'm not proud of it. Now, with
a newly-overhauled engine, I've moved to a spot where I can leave my
Tanis plugging in all winter to protect the investment.


Best of luck,


David

I won't start my 172M without preheat unless it is above 40 degF or has
been running recently - and that's with the multivis Aeroshell.

Lycomings are unusually sensitive to cold start cam damage. My
thinking is that even a single episode can create internal mayhem.

Perhaps my description was not clear enough. My engines do have Tanis
preheaters on them. When I preheat the engine everything is fine, it
starts like a mid-summer day. The problem is when it is cold and I am
unable to preheat due to lack of accessibility to electricity.

M.E. Borner wrote:

Perhaps my description was not clear enough. My engines do have Tanis
preheaters on them. When I preheat the engine everything is fine, it
starts like a mid-summer day. The problem is when it is cold and I am
unable to preheat due to lack of accessibility to electricity.

It might be worth trying to find some other way to preheat when you
cannot plug in (get the plane pulled into a heated hangar, or borrow a
forced-air heater). Your engines might be trying to send you a
message.


All the best,


David

Portable generator?

"M.E. Borner" wrote in message
ups.com...
Perhaps my description was not clear enough. My engines do have Tanis
preheaters on them. When I preheat the engine everything is fine, it
starts like a mid-summer day. The problem is when it is cold and I am
unable to preheat due to lack of accessibility to electricity.