IO520 Hot start

Hi there, I just got my Cessna 340. My right engine is very difficult
to hot start. I have to crank several times. Have done the flooded
start procedure which does not work, the only thing that seems to work
is to do a normal start, bring up the throttle halfway and if the
engine catches a little bit quickly lean out the mixture. But it is a
crapshoot and takes too much effort.

Any good tips and experiences?

When my engine gets hard to start I check the timing. If that is ok, I
replace the plugs. So far that has always done it. I switched to fine
wire plugs which last longer and don't seem to collect the lead at the
base. Hot starts are a bit problematical. I have heard that people do a
special shutdown procedure so they can start it. They flood it at
shutdown and cut it off with the key. That way there is fuel in the
cylinders for the start. You might try that.

Usually when the engine won't hot start it's because of vapor lock or
fuel boiling. You want to get cooler fuel to the engine. Close the
throttle, pull the mixture and run the boost pump for about 60
seconds. Won't hurt the pump and will move the fuel around so that
the cooler stuff is there. Then do your normal starting procedure.

On 26 Mar 2005 17:35:13 -0800, "
wrote:

Hi there, I just got my Cessna 340. My right engine is very difficult
to hot start. I have to crank several times. Have done the flooded
start procedure which does not work, the only thing that seems to work
is to do a normal start, bring up the throttle halfway and if the
engine catches a little bit quickly lean out the mixture. But it is a
crapshoot and takes too much effort.

Any good tips and experiences?

On 26 Mar 2005 17:35:13 -0800, "
wrote:

Hi there, I just got my Cessna 340. My right engine is very difficult
to hot start. I have to crank several times. Have done the flooded
start procedure which does not work, the only thing that seems to work
is to do a normal start, bring up the throttle halfway and if the
engine catches a little bit quickly lean out the mixture. But it is a
crapshoot and takes too much effort.

Any good tips and experiences?

http://groups-beta.google.com/group/... 454d9144c88f

TC

wrote in message
oups.com...
Hi there, I just got my Cessna 340. My right engine is very difficult
to hot start. I have to crank several times. Have done the flooded
start procedure which does not work, the only thing that seems to work
is to do a normal start, bring up the throttle halfway and if the
engine catches a little bit quickly lean out the mixture. But it is a
crapshoot and takes too much effort.

Any good tips and experiences?


I had a hard time hot-starting my IO-360 for a long time.
As it turns out, I was slightly misreading the flooded start procedure.
I *thought* it said to have the throttle full open, and mixture at idle cut
off.
Then, advance the mixture while cranking until it catches.
That NEVER worked.
Finally, I re-read it, and it said to crank with mixture at idle cut off
UNTIL it catches, then advance the mixture, and pull the throttle.
That way works every time.

I doubt your problem was as simple as mine, but who knows ;-)

Adam
N7966L
Beech Super III

On 2005-03-27, mindenpilot wrote:
crank with mixture at idle cut off [and the throttle full open]
UNTIL it catches, then advance the mixture, and pull the throttle.
That way works every time.

This works every time for me with an IO-540. Hook the pinkie and ring
finger around the throttle, position the thumb over the mixture and just
twist when it starts to catch.

--
Ben Jackson

http://www.ben.com/

Our Aztec has the little "spider" fuel distributor on the tops of the
IO540s. The fuel generally gets boiled out of it after shut down, so this
is what works for us.

1. All levers forward, throttles, props, mixtures.
2. Master on
3. Fuel pumps on until the fuel flow needles just barely wiggle... and I
mean just BARELY, all we want to do is fill up the fuel distributor, the
fuel lines, and send maybe a "titch" into the cylinders
4. Fuel pumps immediately off
5. Mixtures to idle cut off
6. Throttles cracked
7. Crank until it fires, mixture forward, add a little throttle, fuel pump
on
It normally turns over several more times than with a cold start and we can
tell when the engines are about to start by watching the blades slow as
compression builds, then they will fire.

We've tried the "full throttle mixture at idle cutoff, crank until it
starts" but it really drains the battery. Aluminum battery cables, 12v
battery located in the right side of the nose, just not a good combination
for cranking and cranking. Our owners manual even mentions starting the
left engine first. This goes back to the days when Aztecs and Apaches only
had an single alternator or single generator on the left engine. Barring
any other reason, it simply doesn't make sense to start the engine furthest
from the battery first if you have alternators on both engines. We start
the right engine first and let it provide extra cranking power to the
battery when starting the left.

What I try to teach people about hot starts is that the fuel/air mixture
will ignite best at one ratio and to think about how to obtain that best
ratio given the conditions. Just as we have to prime more or run richer
mixtures in cold dense air, hot starts and high altitude operations require
just the opposite. Less fuel for less air. We know that the engine is hot,
so the air in the cylinders is hot and very thin, right? So we don't have
to add much gas to obtain our best air/fuel ratio. Your technique of
bringing the throttle up halfway creates a leaner mixture by introducing
more air into the system, a leaner mixture is what we want but I would
rather start by restricting the amount of fuel, and possibly preventing plug
fouling. Work from a lean mixture towards a rich mixture rather than
working from a rich mixture towards a lean mixture and then back towards a
lean mixture.

I'd say to take a good look at your fuel system. Learn where the fuel is
boiling away and how to purge air and replenish fuel to that area without
adding fuel to the cylinders.

Jim



wrote in message
oups.com...
Hi there, I just got my Cessna 340. My right engine is very difficult
to hot start. I have to crank several times. Have done the flooded
start procedure which does not work, the only thing that seems to work
is to do a normal start, bring up the throttle halfway and if the
engine catches a little bit quickly lean out the mixture. But it is a
crapshoot and takes too much effort.

Any good tips and experiences?

On 2005-03-27, Jim Burns wrote:
We've tried the "full throttle mixture at idle cutoff, crank until it
starts" but it really drains the battery. Aluminum battery cables, 12v
battery located in the right side of the nose, just not a good combination

My battery (Comanche) is in the empennage, but it does have the copper
cable mod. My experience with cranking at full throttle (for a hot start)
is that the propeller turns much more easily and much faster, presumably
due to the fact that the intake cycle can breathe more easily. It probably
spins around more times, but starts about as quickly as a cold start.

The Comanche does have a roomy cowl and cools so readily that it doesn't
even need cowl flaps, so it may be that I've never experienced the joy
of a truly hot IO-540 start.

--
Ben Jackson

http://www.ben.com/