Oil pressure gauge

[iflyforpie]

I'm sorry, but I have NEVER NEVER NEVER seen the need to pump a throttle on any of the common and obscure engines I've flown.
It's a wan*er's habit I suppose

+2. The only time I needed to pump a throttle was on a Cherokee 140 I flew that the O-rings in the primer decided to go when I was in the middle of nowhere. It was a bitch to start and I rebuilt the primer as soon as I got home.

Most primer systems go to more than one cylinder. On a typical O-320, three of four cylinders have a primer. The O-300 has only one primer nozzle, but it is in the intake manifold and splits to three cylinders. The O-470 has primer nozzles in all cylinders. The R-1340 I worked on had three cylinder with a primer nozzle that would not only get the engine started on a -20C Calgary winter day, but keep it running after putting the mixture to ICO if the primer wasn't quite locked.

Pretty much all carburetors have an accelerator pump which does shoot extra fuel into the engine. But at cranking RPM it is very difficult for this fuel to get all the way from the carburetor to the cylinders and it will usually collect on the manifold walls and drip back down to the airbox. This pooled fuel is great for catching fire should there be a backfire.

Though I would argue against MichaelP saying the idle jets and nozzles are sufficient (they aren't usually, which is why we crack the throttle on start up) I definitely agree with not pumping the throttle.

[Hedley]

On a typical O-320, three of four cylinders have a primer

uh, no. I have seen 4-cyl Lycoming factory installations
with either one, two or three cylinders fed by the primer,
and the most common I see is one, max two cylinders.

A friend of mine has a 172, he had to change the cylinder
that had the ONE primer line fed to it, because the gas
washed all the oil off the cylinder walls and it scuffed. That
worked really well for him, didn't it?

I just had a conversation last week with a guy who builds
Lycoming engines for homebuilts, he only plumbs two
cylinders from the primer

[iflyforpie]

Every Lycoming 172 I've seen has three cylinders primed. But I guess 172s with O-320s aren't all that common.

Your friend wasn't using mogas was he? Combined with over priming it's a good recipe for scuffed cylinders. A few bucks for some extra primer nozzles and tubing would probably mean he would have to prime as much and offset the cost of a new cylinder.

[Hedley]

A few bucks for some extra primer nozzles and tubing would probably mean he would have to prime as much and offset the cost of a new cylinder

Sure, but that's not what he has, and he'd probably need
an STC for the mod, so that's never going to happen.

Those hand primers are so mickey mouse. They can leak
fuel into your hand, they can plug up and take enormous
pressure to depress, they don't feed all cylinders, etc. Yuck.

Don't get me wrong - an electric boost pump on a
fuel injected engine, that feeds all the cylinders, is
a great way to prime.

[iflyforpie]

On a 172, the installation is standard (like I say, I've never seen one without three cylinders plumbed) so you don't need an STC, you are installing approved parts to what the book already says.

I hate primers too. But I've never had a problem starting any carbureted engine with using one. Fuel injection is better in some ways provided you know what fuel flow/pressure to go to for which temperature you are starting.

But I've spent more time battling a hot start on a fuel injected engine than a carbureted one; and for fear of flooding I am usually pretty lean on the priming in cold weather so it sometimes takes a couple tries there too. My 172, starts first time, every time.

[MichaelP]

You might be able to get away with that in England or British Columbia, or Thailand

That's a little unfair... I have operated in very low temperatures and I have frequently been asked to help my fellow aviators start their engines in very low temps.
I've usually been successful with only a few frustrations.

As for the idle jet and starting with the throttle closed, I use this technique for engines that are already hot and it usually works. In this way I avoid flooding the engine. With a hot engine you can never be certain of your start point, do I need to prime?
Primed might mean flooded, so let's try simple first.

Sometimes I'll give the throttle one pump with a warm engine and an accelerator pump before using the starter. But never more than one as noted above, in cold weather you risk pooling the fuel, in both cold and warm weather you risk flooding.
If I only have the accelerator pump, in cold weather I'll pump once and suck in twice by hand each time. In this way each prime using the throttle is drawn straight into the cylinders by hand.
There's also no ignition source to spark the mixture, backfire, and cause a fire in the carb box or worse.

All propellers are supposed to be fitted in a position for swinging, but some mechanics don't like hand propping and deliberately put it in the wrong position.
The Cherokee's maintenance manuals specify the correct position and so in this type at least the mechanics are counter to the manufacturer's requirements.
The problem is that we have to turn props by hand from time to time and mechanic's opinions can lead to highly dangerous situations.
The Warrior would not start, I wasn't there at the beginning otherwise she would have started.
I helped them out, but the propeller was in the wrong position, and so I had to be doubly careful how I turned it.
The aeroplane did not fly that day... With the prop in the correct position it might have, Michael would have swung it!
Imagine that aeroplane being stuck somewhere and a desperate pilot trying to swing a wrongly positioned propeller with the greater risk of serious injury...

[iflyforpie]

I thought that the position of the prop was for engine balance. Usually with the dowel pins it is almost impossible to put it on another way, but you are right, the 10 o'clock position is perfect for hand bombing.

Warm engine starting at idle usually works, but not when cold I find. For fuel injected engines I usually start at idle and gradually open when cranking so at some point there will be a perfect mixture of fuel (without the accelerator pump screwing things up like in a carb-equipped engine).

[MichaelP]

All engines have their foibles...

The IO-240 is a bugger to start at the best of times and yet the more powerful carburettor equipped Roll Royce O-240 was easy to start.
I know we're in for a big bill at some time with this hard to start much abused engine... There's also all the ground running time with maintenance trying to make that ill founded injection system work. It still does not work well... Give me a carburettor please!

The IO-360 in the DA40 is easy to start even when hot while it's carburetted version was a bugger hot!

The 0-200, C90, C85 series are the easiest starting engines ever, as long as you don't prime when hot.
These engines I start from throttle idle when they are hot and this works well.

The 0-235 likewise likes throttle closed and no prime when hot.
When cold this engine starts easily if you prime and suck, prime and suck, prime and suck four or five times before touching the starter.
I watch people crank these engines over and over while the battery dies. Sometimes the prime catches fire all down the nose leg, and I have seen the air filters burned away.
I do what I do, get in and she's running within two turns of the starter motor, so what's the best method?

Treat the propeller live, ensure mixture ICO, mags off, throttle closed, chocks in, competent person in cockpit, and check these items twice before turning by hand.

BTW there's no peg on the Cherokee's O-320... My brother put the propeller into what he'd heard was the smooth position. I wouldn't swing it. It's in the maintenance manual position now which is the correct position for swinging.
I see no difference to the smoothness, it still feels like a John Deere perhaps.

For many aircraft engines, if they are not starting easily there are fundamental problems.
Check the setup of carb/injector, and especially the timing.
When were the mags checked last?
500 hours? 5 years?
Besides that IO-240 I know of no engines that could not be started with reasonable effort.

I had trouble swinging Pitts propellers... Philip Meeson would come in, everyone friendly, then when he was leaving the place would suddenly be empty and Michael would be left with the hard job of swinging his prop
This was timing... Sometimes the mags are set too far advanced, better fo power at high revs, but bad for starting.

[Hedley]

I had trouble swinging Pitts propellers

Try a 3-blade claw, with sharp trailing edges, on
a high-compression AEIO-540 sometime

A friend of mine had his four-cylinder 200hp AEIO-360
starter die in his S-1T at a contest, years ago. The
tea and crumpets contest crowd quite specifically did
NOT approve of my hand-propping him. Amongst
other things. But, with it's two-blade metal prop,
and his expert priming, it was a cinch.