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The 3003rd lycoming hot start thread


bradp

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What do you guys think?

 

For my 30 min turnaround to pick up our pup yesterday, I was of course fretting about how my IO-360 was going to start up once it was totally heat soaked.

 

I changed my methodology slightly. With a n=1 good result.

 

On shutdown:

 

1) instead of pulling the mixture at 1400 rpm, I set throttle to 1400 rpm, I cut the mags to shut down, leaving the mixture open and more fuel in the lines. Once engine shut down Mixture to cutoff.

 

The reason is usually It usually tries to catch on hot starts and then pitters out, indicating that I am too lean. It's historically difficult for me to find the correct A/F mix on a true hot start (imo DMax's video is not really a heat soaked fuel evap'd hot start). And we've all been there done that flooded the darn thing and then had to crank through to the proper A/F ratio with the resulting embarrassment of hitting 1600 or more rpm and dialing it all the way back to idle while having to stomp in the brakes.

 

So I wanted to leave a bit more fuel in the system....

 

On start:

 

2) I pressurized with boost and mixture ICO and didn't do anything else. I left the throttle where it was.

 

3) yesterday I also tried leaving the electric boost pump on as I was cranking to get more pressurized fuel to the bendix during cranking when the engine driven pump is probably not working at peak efficiency at low RPM.

 

4) Crank until it starts to catch and slowly put in the mixture. The extra fuel pressure with the electric boost pump helps at this step.

 

Result (again n=1): four blades and were off! I wouldn't have said anything but even my wife was surprised that it stated relatively effortlessly.

 

Comments suggestions?

 

 

 

 

Sent from my iPhone using Tapatalk

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I don't fear hot starts.  Taught by transition instructor.   Shut down at 1100 rpm by pulling mixture.     On start up.  Do nothing except crank.  Then add mixture when fires.

How do you know it is flooded?  When you add mixture and it dies. 

When flooded.  Open throttle full open, closed mixture.  Crank.   When fires, do the two handed dance on mixture and throttle to keep running.

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3 hours ago, Yetti said:

I don't fear hot starts.  Taught by transition instructor.   Shut down at 1100 rpm by pulling mixture.     On start up.  Do nothing except crank.  Then add mixture when fires.

How do you know it is flooded?  When you add mixture and it dies. 

When flooded.  Open throttle full open, closed mixture.  Crank.   When fires, do the two handed dance on mixture and throttle to keep running.

Basically my method and works 99.9% of the time.  When it doesn't you either have too much or too little fuel and just need to figure out which.  End of the day when in doubt flood it and do the two handed dance. 

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I do hot starts as follows (in-360 a1a) 

shut down rpm 1000 ICO

on start up I leave it in ICO

full throttle boost pump on

with boost pump still on, close throttle and open slightly 1/8" and start engine. 

Advance mixture as it fires

Fires at about two turns of the prop every time. 

Mike

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When I do a hot start, I have a very similar procedure.  I just assume its flooded.  Mixture to cut off, throttle full forward.  Crank until it catches and then push the mixture in and as fast as  can pull the throttle back at the same time

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Try this, for Lycoming IO models only:

Throttle and mixture fully forward for 10 seconds or more. If you watch the fuel pressure gauge you'll see the fuel pressure drop to 0.

So now you have no fuel in the lines. I do this as soon as I get in, then adjust the seat, seat belts, etc while waiting.

Pull throttle back to what would be 1200 rpm setting or so, mixture to ICO.

Pressurize the fuel system by using boost pump just for a second, then without delay start as normal.

By emptying the fuel lines you are putting in cool fuel and always starting from the same state as oppose to have some of the fuel vaporized out. Starts will be smoother and won't cough and stutter.

 

The problem with other techniques is they may work fine for a short fuel stop but not longer stops, or work when cool but not hot. This insures every hot start is the same, starting from the same state.

Whether it's been 5 minutes or 25, 10° or 90°.

 

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on my io360 so far this has been reliable.  My cfi and I got half stuck the first few times we went for gas with a quick turnaround time.  Ill add my theory below the lines.

I try to open the oil check hole to vent some heat out after I land for starters.  cowl flaps obviously open. I never even think to point into the wind but that couldnt hurt.

full throttle, full mixture.  pump on for 3-5 seconds. (push cold gas through the system)

full throttle, mixture cutoff (its now flooded with cold gas, so full throttle to blow it out, mixture off to not add more to the problem)

crank

when it starts to fire do the one handed magic trick of mixture in and throttle out at the same time.  (mixture richer because it needs those three things to internally combust.  throttle out because it hasnt fired and doesnt need all that gas yet. and it makes a hell of a racket at full throttle.)

about half the time mine is really cranky after a hot start and stumbles and sounds like shit until I do the runup and I keep the RPMs up around 1100 because I dont want it to shutoff on me.

I havent run a tank dry yet because Im worried about how much of a bitch it is to hot start.  I dont want to do magic tricks with mixture and throttle while maintaining best glide to the nearest airport ;)  I bet the prop spinning at 2400RPM or more has more gumption than a starter but Im not brave enough to try it.  yet.

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on my io360 so far this has been reliable.  My cfi and I got half stuck the first few times we went for gas with a quick turnaround time.  Ill add my theory below the lines.

I try to open the oil check hole to vent some heat out after I land for starters. 

full throttle, mixture cutoff (its now flooded with cold gas, so full throttle to blow it out, mixture off to not add more to the problem)

crank

when it starts to fire do the one handed magic trick of mixture in and throttle out at the same time.  (mixture richer because it needs those three things to internally combust.  throttle out because it hasnt fired and doesnt need all that gas yet. and it makes a hell of a racket at full throttle.)

about half the time mine is really cranky after a hot start and stumbles and sounds like shit until I do the runup and I keep the RPMs up around 1100 because I dont want it to shutoff on me.

So let's critique this:

1. You are trying to vent the heat because the technique is bad, if it was good you would not need to do that.

2. You are just flooding the engine, and avoiding the hot start, and need to do a magic trick.

3. With all that it still is cranky

 

Try my method (at home airport if afraid of getting stuck), no cranky starts, no magic tricks required.

Edit: not really my method, my mechanic who owns a J recommended it.

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One more thread that makes me glad I fly behind an O-360 . . . Stopped for fuel Sunday, added 27 gals to top off, pumped throttle once, mixture rich, turn & push key--purr. Right on 1000 RPM (I sometimes miss by a couple hundred RPM, but Sunday was nice). 

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I have been doing the following for 15 years in my IO360. Works everytime.

At shutdown - At idle (1000RPM), mixture to cutoff. - Pretty much a normal shutdown, things should be as normal as possible anyway.

Startup -  Master switch on, leave throttle where it was (if you accidently moved it, no problem just crack it slightly above idle) - mixture stays in cutoff. NO FUEL PUMP!!!! (you will flood the engine for sure!) - now start the engine it will turn over 3 or 4 times then fire, bring mixture to rich as it fires.

The only time I was having major issues getting started it turned out I need my mags overhauled.....

 

 

Edited by Mooney_Mike
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Just now, Mooney_Mike said:

I have been doing the following for 15 years in my IO360. Works everytime.

At shutdown - At idle (1000RPM), mixture to cutoff. - Pretty much a normal shutdown, things should be as normal as possible anyway.

Startup -  Master switch on, leave throttle where it was (if you accidently moved it, no problem just crack it slightly above idle) - mixture stays in cutoff. NO FUEL PUMP!!!! (you will flood the engine for sure!) - now start the engine it will turn over 3 or 4 times then fire, bring mixture to rich as it fires.

 

 

+1

Switch to Tempest fine wire plugs, a Concorde battery and DMax's simple hot start technique should work fine.

The IO360 is easy to flood so best practice is to err on the side of fuel starvation by cranking with the mixture in cut off position w/o the boost pump. If engine doesn't catch quickly I pump the red knob once. As soon as it shows a sign of catching quit cranking and give it a little mixture while getting the left hand to the throttle.

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My theory is the vintage planes have easier hot starts because of the guppy intake vents the heat better, so less vaporization. The factory method which is what Mike describes (as well as DMax) works well for short stops even on the J, longer stops it will take a lot more blades because it has to flush out all that vaporized fuel, which is why Bob mentions needing a Concord battery.

DMax has a YouTube video showing the hot start method, but he is hot starting after on a minute or two, if he wants to impress, he would  let it sit for 20-30 minutes in the Texas summer heat. 

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3 hours ago, tony said:

When I do a hot start, I have a very similar procedure.  I just assume its flooded.  Mixture to cut off, throttle full forward.  Crank until it catches and then push the mixture in and as fast as  can pull the throttle back at the same time

This works for me as well.  Just a caveat to this approach, if the plane has been sitting for say three hours.  I crack the throttle with mixture all in(no boost) and usually fires up.  We call that a warm start.

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39 minutes ago, teejayevans said:

My theory is the vintage planes have easier hot starts because of the guppy intake vents the heat better, so less vaporization. The factory method which is what Mike describes (as well as DMax) works well for short stops even on the J, longer stops it will take a lot more blades because it has to flush out all that vaporized fuel, which is why Bob mentions needing a Concord battery.

DMax has a YouTube video showing the hot start method, but he is hot starting after on a minute or two, if he wants to impress, he would  let it sit for 20-30 minutes in the Texas summer heat. 

My vintage E a 201 style cowl with smaller air intakes. But I have seen several experienced Mooney drivers open the oil dipstick door when they are making a brief stop. I suppose that can't hurt though that does not directly vent the top of the engine.

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1 hour ago, TheTurtle said:

I havent run a tank dry yet because Im worried about how much of a bitch it is to hot start.  I dont want to do magic tricks with mixture and throttle while maintaining best glide to the nearest airport ;)  I bet the prop spinning at 2400RPM or more has more gumption than a starter but Im not brave enough to try it.  yet.

Restarting in the air after running a tank dry is not an issue I've done it several times on long flights.  The injected engines in my experience usually quit pretty quickly when out of fuel since there is no fuel bowl like on carburetors.  The engine continues to spin at RPM no starter is needed.

Close throttle (so you don't get an engine over-speed when it gets fuel), switch tanks, boost pump on she will fire up quickly advance throttle to previous setting adjust mixture for cruise if necessary.  You may experience some roughness at first but that passes quickly and could just be imaginary. 

Oh also warn your passenger that it is coming so they don't have a heart attack.  I've been able to catch it pretty much as soon s the engine start to lose RPM knowing it is coming.

 

 

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I no longer fear hot starts. ('78J)

I crack the throttle, mixture at cutoff, no boost pump, crank.  If it hasn't caught within 2 or 3 seconds I slowly advance the mixture toward mid-point.  If it still hasn't caught I abandon the start.

If the above didn't work, I leave the throttle cracked open, mixture full rich, boost pump on until I see pressure (about 1 second), then repeat the above.

Hasn't failed me yet since I've started doing that.

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Restarting in the air after running a tank dry is not an issue I've done it several times on long flights.  The injected engines in my experience usually quit pretty quickly when out of fuel since there is no fuel bowl like on carburetors.  The engine continues to spin at RPM no starter is needed.
Close throttle (so you don't get an engine over-speed when it gets fuel), switch tanks, boost pump on she will fire up quickly advance throttle to previous setting adjust mixture for cruise if necessary.  You may experience some roughness at first but that passes quickly and could just be imaginary. 
Oh also warn your passenger that it is coming so they don't have a heart attack.  I've been able to catch it pretty much as soon s the engine start to lose RPM knowing it is coming.
 
 

Id assume you leave the mixture alone during this entire process, yes?
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7 hours ago, teejayevans said:

Try this, for Lycoming IO models only:

Throttle and mixture fully forward for 10 seconds or more. If you watch the fuel pressure gauge you'll see the fuel pressure drop to 0.

So now you have no fuel in the lines. I do this as soon as I get in, then adjust the seat, seat belts, etc while waiting.

Pull throttle back to what would be 1200 rpm setting or so, mixture to ICO.

Pressurize the fuel system by using boost pump just for a second, then without delay start as normal.

By emptying the fuel lines you are putting in cool fuel and always starting from the same state as oppose to have some of the fuel vaporized out. Starts will be smoother and won't cough and stutter.

 

The problem with other techniques is they may work fine for a short fuel stop but not longer stops, or work when cool but not hot. This insures every hot start is the same, starting from the same state.

Whether it's been 5 minutes or 25, 10° or 90°.

 

I'm going to give this a shot.  Like everyone else here, a quick fuel stop is not an issue; it's the 30 minute stop that wreaks havoc.  

Question: When i cold start, i leave the mixture full rich, are you starting using this technique with the mixture in ICO?  Do you kill the boost pump before starting or turn it on and start?

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I'm going to give this a shot.  Like everyone else here, a quick fuel stop is not an issue; it's the 30 minute stop that wreaks havoc.  

 

Question: When i cold start, i leave the mixture full rich, are you starting using this technique with the mixture in ICO?  Do you kill the boost pump before starting or turn it on and start?

Cold start is mixture full rich, throttle at 1/4", turn on boost pump for 7-10 seconds depending on temperature. Boost pump off, mixture back to ICO. Usually starts in 1-2 blades. If it doesn't start right away and it's cold, I'll repeat boost pump step for another 2-3 seconds.

My mechanic told me you can't have a Lycoming too rich on a cold start, but I haven't tested this theory.

BTW, on hot starts, somebody mentioned this, you don't need to go full rich, when hot this can cause the engine to stumble (like pulling choke when engine is hot), you only need to go half way, you can use your extended index finger to stop from going too rich.

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Ok with all the variation in technique next time we have a gathering with more than say 5 IO-360s, we need to have everyone try their own tested method or some other prescribed method to work out which is actually the most reliable. Almost like a "Hot-start-off".




Sent from my iPhone using Tapatalk

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On 2/21/2017 at 6:05 AM, Mooney_Mike said:

I have been doing the following for 15 years in my IO360. Works everytime.

At shutdown - At idle (1000RPM), mixture to cutoff. - Pretty much a normal shutdown, things should be as normal as possible anyway.

Startup -  Master switch on, leave throttle where it was (if you accidently moved it, no problem just crack it slightly above idle) - mixture stays in cutoff. NO FUEL PUMP!!!! (you will flood the engine for sure!) - now start the engine it will turn over 3 or 4 times then fire, bring mixture to rich as it fires.

The only time I was having major issues getting started it turned out I need my mags overhauled.....

 

 

You will not flood the engine if the mixture is at ICO.  In fact, some Times you should have the pump running during start, because th engine starts then will die immediately after due to vapor locked fuel lines. A running fuel pump prevents this..

 

Edited by jetdriven
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10 minutes ago, jetdriven said:

You will not flood the engine if the mixture is at ICO.  In fact, some Times you should have the pump running during start, because th engine starts then will die immediately after due to vapor locked fuel lines. A running fuel pump prevents this..

 

That hasn't been my experience. I don't use the fuel pump on hot engine starts.

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