Cold Weather, Remember how to Start Engine

A guy showed me a trick for cold starting the C172SP IO-360: after running the fuel pump (mixture rich), wait 60-120 seconds for the fuel to vaporize in the cylinder, then attempt starting (mixture cutoff until she fires, usually 2-3 blades). Worked well for me when I was working as a CFI.
 
How big is your fire extinguisher? :mad3:

To be serious, no I haven’t. That would be a lot of ether that’s in the long and wide intake tube leading to the carb box. A backfire at this time would be a fuel air “boom”. The idea gives me great pause. Interested in hearing others.
 
AV8R_87 said:
I wonder what their reasoning was. That air is usually less than 120F, and it uniformly warms up the engine. I don't see any issues with doing that to an engine for an hour or two in cold weather, warming everything up.
If anything, I wonder if their concern is not warming the engine enough, leading to uneven temperatures. I recall some people were against oil pan heaters because it did nothing for the cylinders.
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I have a vague recollection of someone explaining to me that with continentals the moisture evaporated out of the oil would condense further up in the engine and cause corrosion problems. Hopefully posting this will get someone to confirm or deny.
 
AV8R_87 said:
I wonder what their reasoning was. That air is usually less than 120F, and it uniformly warms up the engine. I don't see any issues with doing that to an engine for an hour or two in cold weather, warming everything up.
If anything, I wonder if their concern is not warming the engine enough, leading to uneven temperatures. I recall some people were against oil pan heaters because it did nothing for the cylinders.
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As I recall, it was a concern about uneven heating.
 
Gilbert Buettner said:
When I owned a V-tail Bonanza, the engine operating instructions specifically advised against this way of pre-heating. I used an oil pan pad heater and a big quilt or moving blanket over the cowl. Always the night before flying in northern Minnesota, Wisconsin and lower Michigan. I often flew when OAT was below zero F.
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AV8R_87 said:
I wonder what their reasoning was. That air is usually less than 120F, and it uniformly warms up the engine. I don't see any issues with doing that to an engine for an hour or two in cold weather, warming everything up.
If anything, I wonder if their concern is not warming the engine enough, leading to uneven temperatures. I recall some people were against oil pan heaters because it did nothing for the cylinders.
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On my Mooney I have 2 Revlon hair dryiers. Low is about 800 watts. I put one in each cowl flap and a blanket over the cowl to heat both sides evenly. I preheat if below 30°F. I also own a battery operated propane forced air heater. I thought I could use it if away from home, but it is not as reliable.
 
If you are cold starting a carburerated engine with a working fuel priming pump this method will start it every time. Set carb open about 1/4 throttle, or just crack open about twice as far as you normally would on a warmer day. Pull the primer out and be ready to pump. Begin cranking and after the first blade passes the windscreen begin pumping vigorously until it starts, then stop pumping. Be ready to pump again in 2-3 seconds if the engine stalls. Adjust throttle and pump again as needed to keep engine running at low speed until pumping is no longer needed. Lock down the primer and let the engine warm up at low speed.

This works because you are moving the AF ratio from a too lean to fire condition to a rich enough to fire condition. If it is cold outside and the engine is cold it will likely go lean and stall again 2 seconds or so after starting. Pump again as it spins down just enough to keep it running. As the heat builds the gas will evaporate better and engine will run OK on its own. This method worked every time on my old Cherokee O-320 Lycoming.
 
it’s unlikely the two hair dryers can adequately warm the oil in an hour or two in sub 10° temperatures, which is what Lycoming uses as their preheat threshold.
 
WDD said:
Us tie down, hangar challenged folks without electricity just have to make do with propane.
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Actually someone here pointed out the jackery line of portable batteries…just plug in your tanis to the jackery and 30 minutes later you can go!

Of course that works once unless you have a solar panel or a regular outlet to recharge from
 
Pinecone said:
And they were against LOP operations. :D
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I don't agree that Lycoming excludes LOP operations. Service instruction 1094D states:
"For a given power setting, best economy mixture provides the most miles per gallon. Slowly lean the mixture until engine operation becomes rough or until engine power rapidly diminishes as noted by an undesirable decrease in airspeed. When either condition occurs, enrich the mixture sufficiently to
obtain an evenly firing engine or to regain most of the lost airspeed or engine RPM. Some engine power and airspeed must be sacrificed to gain a best economy mixture setting."

That sounds like LOP operations to me.
 
William Pete Hodges said:
If you are cold starting a carburerated engine with a working fuel priming pump this method will start it every time. Set carb open about 1/4 throttle, or just crack open about twice as far as you normally would on a warmer day. Pull the primer out and be ready to pump. Begin cranking and after the first blade passes the windscreen begin pumping vigorously until it starts, then stop pumping. Be ready to pump again in 2-3 seconds if the engine stalls. Adjust throttle and pump again as needed to keep engine running at low speed until pumping is no longer needed. Lock down the primer and let the engine warm up at low speed.
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Carbureted engines will be a lot easier to start if they have a few new primer nozzles.

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This little thing is what sprays the fuel into the intake manifold. It's more than just a fitting with a tiny hole in the business end. Behind that little round plate that's staked into the end of the fitting are some tiny machined channels that take the fuel via tiny holes from the fuel inlet, and those channels are at a tangent to the center hole. The fuel is made to spin at a high rate so that when it exits it forms a conical, fine spray that vaporizes well and fires off promptly.

These fittings have residual fuel in them after priming, and when those nozzles are in the cylinder head they get real hot and the fuel in them cokes them up and they won't work right anymore. They'll just dribble the fuel, and that dribbling fuel is large droplets that just end up running down the intake port walls instead of being sucked into the cylinder in a rich vapor that will ignite nicely. I have tried to clean them but it's pretty much impossible. The passages are so tiny. I even built a pressure canister with threaded ports to screw these into, with strong carb cleaner/carbon dissolver in the canister under pressure to force it through to clean the nozzles. Didn't work. I spent more money (time) fooling with that than the cost of several new nozzles.

The larger Continentals used two 90° nozzles, one in the aft end of each intake runner, AN4023-1:

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They last a lot longer because they're far from the heads and don't get so hot.

I had one customer whose airplane (a 180) was hard to start. I found that someone had replaced plugged primer nozzles with these AN fittings, which are straight through and don't atomize anything:

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I put in two new AN4023-1 nozzles, reinstalled the proper tube end fittings, and boy did that O-470 fire up instantly.
 
I was previously priming my engine, yelling "clear", and then waiting a few seconds before engine start. Worked okay, but the engine sometimes took a bit to get going. Then I read /heard somewhere (I want to say it was a Mike Busch book or podcast) that pushing the primer in *while* turning the starter (instead of before) is more effective. I tried it (two priming strokes and the third once the starter is engaged), and holy cow it's a much more immediate start. Has definitely helped on some cold mornings!
 
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