Cold Starting Procedure and I'm an Idiot

Mtns2Skies said:
I agree with @Tom-D . I give the last shot of prime while I'm cranking the engine and I notice it starts WAY better(3 hands required ;) ) Particularly in cold weather. One CFI showed me this and explained it's because the primer aerosolizes the fuel. If you wait too long it re-liquifies and is harder to start..
Click to expand...

I think the phrase you were looking for was "atomizes the fuel".


Sent from my iPhone using Tapatalk
 
Tom-D said:
Post #1 we were talking about a 0-320-
Click to expand...

Fine. Refer to Figure 31 of the O-320-A and E series parts catalog, and the O-320-B and D parts catalog. Those O-320 models prime all four cylinders. The ancient narrow deck O-320s only primed 3 cylinders.
 
Tom-D said:
Just because you've never heard of it, before doesn't make it wrong.
Remember the POH says " prime as required"
My method is a better method, pull the primer out, allow it to fill, turn the mags on, crack the throttle a wee bit, start cranking and pushing the primer in. the first cylinder to suck in fuel will fire and the engine will start and run.
Click to expand...
What engine? This is interesting...
 
Stingray Don said:
Welcome to this week's edition of Idiot's Anonymous. Hi, my name is Don, and I'm an idiot.
Click to expand...
"Hi, DON!!" :D
Welcome to IA.

Stingray Don said:
I recently stumbled on the fact that you have to wait at least 2-3 seconds for the fuel to fill the primer before pushing it back in. I had never heard that before and I've always just pumped the thing as quickly as I could and then started cranking (doh!).
Click to expand...
That is one of the secrets that are not found in any books. You discovered by feel, that is good. That means you have the feel. (Lord knows many out there don't)

Now go enjoy the plane and sin no more. Hallelujah! :)
 
Tom-D said:
two different configurations of the oil sump used on the 0-360 one of which is a side draft that until now I never knew existed, And is noted in the application list is only found on a bastard child of Cessna C-177RG
Click to expand...

You've got some bad data there, Cessna built no Cardinals with side draft carbs. And no 177RG came with any kind of carb.

Paul
 
Mtns2Skies said:
I agree with @Tom-D . I give the last shot of prime while I'm cranking the engine and I notice it starts WAY better(3 hands required ;) ) Particularly in cold weather. One CFI showed me this and explained it's because the primer vaporizes the fuel. If you wait too long it re-liquifies and is harder to start..
Click to expand...

SoonerAviator said:
I think the phrase you were looking for was "atomizes the fuel".


Sent from my iPhone using Tapatalk
Click to expand...
Or more accurately 'vaporizes.'
 
slacktide said:
Fine. Refer to Figure 31 of the O-320-A and E series parts catalog, and the O-320-B and D parts catalog. Those O-320 models prime all four cylinders. The ancient narrow deck O-320s only primed 3 cylinders.
Click to expand...
172 N = 0-320-H2AD primes 2
 
Tom-D said:
No I just looked up the side draft carb you have is a Bendix pressure carb. it works on a different principal that the Marvel Shebler that real aircraft have :)
correct that, Marvel is now making them, and have renamed them the HA-
Click to expand...

The HA-6 is not a pressure carb. It's a normal float-type carb and seen on several Lycomings, including the O-540-J3C5D in the 182RG I used to look after and flew some.

Go to http://www.insightavionics.com/pdf files/MA-4 Carb Manual.pdf and scroll down to Pages 27-32.
 
Last edited:
slacktide said:
Also incorrect. Refer to figure 34 in the O-360-A parts catalog. The number of primer lines is dependent on the engine model, and there are several models that prime all 4 cylinders.
Click to expand...
The number of cylinders primed is dependent on the airframe manufacturer, not the engine maker. You will find the priming system described in the airframe manufacturer's service manual and parts catalog. The O-320-E2D that was so popular in 172s between 1968 and 1977 or so had three cylinders primed.
 
GeorgeC said:
The flip side is to wait a bit between priming and cranking to give the fuel a chance to evaporate.
Click to expand...
And that there is the precursor to an induction fire. The fuel sprays into the intake port and promptly strikes the walls and starts running down through the manifold and out of the carb into the airbox and then into the cowling. It's worse in cold weather, because like any other liquid, evaporation is much slower in low temperatures and saturation happens much sooner. If the engine has a backfire (defined as flame out of the intake, as opposed to afterfire, which is fuel igniting in the exhaust), that backfire will set the draining fuel afire. And lean mixtures backfire real easy.

Sure, one can go by the POH and prime and then sit there and fool around doing the other checklist items while the fuel drains out instead of being sucked into the cylinder where it actually works for you instead of burning up your airplane. Tom is right: prime and crank immediately. It works much better and more safely, and especially so in cold weather.

An item that is often overlooked when an owner complains of hard starting: Those primer nozzles. AN-4022-1, IIRC, for the straight version. They are little brass fittings that have tiny swirl chambers in them that spin the fuel as it passes through so that it spreads into a cone-shaped mist as it exits the microscopic hole in the tip. It's a centrifugal sprayer. And it has fuel left in it as the cylinder head heats up; that fuel boils off and leaves varnish, and over the hundreds of hours it clogs up and the misting effect suffers or stops altogether. They are very hard to clean, and it's cheaper to replace them. You won't believe the improved starting with a new set of nozzles. And how easy the primer will then push inward, too.
 
I'm with Tom on this one. From a fuel supply point of view, it makes sense. And in my experience with O200, it simply works. If it's really cold outside, I prime once, then on second push I start cranking. Always starts before primer is back in. Filling the manifold with fuel isn't a very effective way to prime, and 6 "squirts" is A LOT of fuel, waaay more than the engine really needs to fire.
 
mtuomi said:
I'm with Tom on this one. From a fuel supply point of view, it makes sense. And in my experience with O200, it simply works. If it's really cold outside, I prime once, then on second push I start cranking. Always starts before primer is back in. Filling the manifold with fuel isn't a very effective way to prime, and 6 "squirts" is A LOT of fuel, waaay more than the engine really needs to fire.
Click to expand...

When one considers the small volume of air in the top end of the intake manifold, you start to realize that a lot of prime before cranking is doing no good. That little bit of air can only hold a small amount of vapor, and the rest just runs down and out. And in cold weather, the vapors could be insufficient to fire the engine on their own, due to saturation. Cranking while priming draws the mist into the cylinder and disperses it into a larger volume, and the heat of compression vaporizes it into a useful, combustible mixture.
 
Tom-D said:
the bendix that it mimics was .
This old carb could be mounted in any position and work.

http://www.navioneer.org/riprelay/The Navion Files/Bendix1.pdf
Click to expand...


The HA-6 looks like this:

DSCF1167_0.JPG


Nothing at all like the Bendix PS carb.
 
Dan Thomas said:
When one considers the small volume of air in the top end of the intake manifold, you start to realize that a lot of prime before cranking is doing no good. That little bit of air can only hold a small amount of vapor, and the rest just runs down and out. And in cold weather, the vapors could be insufficient to fire the engine on their own, due to saturation. Cranking while priming draws the mist into the cylinder and disperses it into a larger volume, and the heat of compression vaporizes it into a useful, combustible mixture.
Click to expand...

Exactly. 6 doses of primer without cranking is crazy.
 
Dan Thomas said:
When one considers the small volume of air in the top end of the intake manifold, you start to realize that a lot of prime before cranking is doing no good. That little bit of air can only hold a small amount of vapor, and the rest just runs down and out. And in cold weather, the vapors could be insufficient to fire the engine on their own, due to saturation. Cranking while priming draws the mist into the cylinder and disperses it into a larger volume, and the heat of compression vaporizes it into a useful, combustible mixture.
Click to expand...
And when I advocate that same thing, the thread goes crazy. :)
 
Dan Thomas said:
The number of cylinders primed is dependent on the airframe manufacturer, not the engine maker. You will find the priming system described in the airframe manufacturer's service manual and parts catalog. The O-320-E2D that was so popular in 172s between 1968 and 1977 or so had three cylinders primed.
Click to expand...

How an airframe manufacturer chooses to modify an engine for their particular installation is their business. It does not change the fact that the Lycoming O-320-E2D was certified with primer nozzles and lines installed in all four cylinders, and that the claim that Lycoming only ever primes 3 cylinders is patently false.

j6hf75.jpg
 
Dan Thomas said:
The HA-6 looks like this:
Nothing at all like the Bendix PS carb.
Click to expand...
Believe me,, I know the difference. the HA-6 is to the old bendix as the pinto was to the model "T"
 
slacktide said:
How an airframe manufacturer chooses to modify an engine for their particular installation is their business. It does not change the fact that the Lycoming O-320-E2D was certified with primer nozzles and lines installed in all four cylinders, and that the claim that Lycoming only ever primes 3 cylinders is patently false.

j6hf75.jpg
Click to expand...
With all your arguments, the engine on the 172N is the H2AD not the E2D. when and if the -N was updated your implication would be correct. but post 1 was ?
 
It is the opposite of spraying cold water on your hot engine for easier starts. You just spray hot water on your cold engine and you will see faster starts.
 
My O-320 has one primer line to #3 and the fuel goes directly into the cylinder. To prime and turn the key and adjust the throttle all at the same time I would need two hands on my left arm. That would mess up my sweaters.
 
cgrab said:
My O-320 has one primer line to #3 and the fuel goes directly into the cylinder. To prime and turn the key and adjust the throttle all at the same time I would need two hands on my left arm. That would mess up my sweaters.
Click to expand...

Wait, I thought we established on page 1 that individual cylinders were not primed? :dunno:
 
cgrab said:
My O-320 has one primer line to #3 and the fuel goes directly into the cylinder'S intake port.. To prime and turn the key and adjust the throttle all at the same time I would need two hands on my left arm. That would mess up my sweaters.
Click to expand...
FTFY. just because the primer line goes to the cylinder head casting does not mean it is placing fuel into the combustion chamber.
Why would you be doing all those things at once? won't your throttle stay where you put it? pull the primer plunger out, while it is filling adjust the throttle and lock the friction knob, now place one hand at the key/starter button/ pull to crank handle/ or what ever. place the other hand on the primer plunger. start cranking push plunger. I believe that's two hands.
 
GeorgeC said:
Wait, I thought we established on page 1 that individual cylinders were not primed? :dunno:
Click to expand...
That will depend upon the make model of the engine, the 0-200, is primed at the intake spider where all 4 cylinders get their fuel air mixture. the 0-300 has 1 primer nozzle in the left "Y" piper and only primes 2,4,6, cylinders, the Lycomings prime at the intake port of the cylinder head, you can arrange them to prime any cylinder you like. most small radial engines prime at the plenum chamber where all cylinders get their fuel air mixture.
 
Tom-D said:
Brian, YGTBSM. there are a multitude of ignition sources that can light off an engine compartment fire, bad mag lead. the mag points them selves, any loose wire that can arc, generator brushes, starter re-lays, battery master re-lays.

What gets destroyed in an induction fires? how about the red Scat hoses in the piper induction system, the filter, and when they're gone what stops the fire from spreading to the fuel in the cowl?
Click to expand...

Yeah I probably oversteped my expertise about induction fires. In over 4500 starts in conditions form -10 to 105F. I have only had a couple inductions fires and they were all in cessna's, none were bad enough that the mechanic didn't just look at it, reassemble and said go fly. Even Even your list of non faulty ignition sources, most are usually behind the Air Baffles so it would take a lot to enough fuel vapor back there to cause an issue.

The main point was, if you watch very many cold engine starts, and quite a few warmer ones, you will see a lot of fuel dripping from the engine compartment on carberated engines, and it is still very rare to have a fire.

Still, Rare is not zero, if you engine will start without the dripping fuel, I highly recommending doing so.

Brian
 
brcase said:
Still, Rare is not zero, if you engine will start without the dripping fuel, I highly recommending doing so.
Brian
Click to expand...
really,, is easy to be cranking as you add fuel, then the fuel goes up not down. It will be sucked into the cylinders much faster and you won't need the 4-5 shots of fuel.
 
Tom-D said:
try my method, you might like how fast the engine will start.
Click to expand...

It wasn't the coldest of days today, but feeding in the last shot of primer while cranking seemed to work pretty well.
 
GeorgeC said:
It wasn't the coldest of days today, but feeding in the last shot of primer while cranking seemed to work pretty well.
Click to expand...
yup.....for my Six....after 4-5 shots I always left the last shot for cranking....but it did need the pre-cranking shots.
 
GeorgeC said:
It wasn't the coldest of days today, but feeding in the last shot of primer while cranking seemed to work pretty well.
Click to expand...
Why weren't you cranking on the first shot?
Here is where the fuel went on the first shots.
 

Attachments

  • 20170203_111643.jpg
    20170203_111643.jpg
    162.2 KB · Views: 50
  • 20170203_111637.jpg
    20170203_111637.jpg
    212 KB · Views: 46
Every plane has its little peculiarity that gets it started first crank. But you have to try different things to find it.
 
You must log in or register to reply here.
Back
Top