The dreaded warm start

Challenged

Challenged

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Challenged
What technique do you employ if you're away from your engine for just long enough that things aren't clearly cold start / hot start? How long is the amount of time?
 
full power full lean, turn the fuel pump on and start cranking, once it acts like its trying to start go to idle and full rich at the same time. time wise? i dont know. its 100 degrees out every day so...tomorrow?
 
If the cowl is still warm to the touch than I consider it a hot start. Of course the technique will vary between an IO & O engine, but for me it’s just mix full rich, crack the throttle and turn the key.
 
Depends on the airplane and the type of fuel system it has.
 
Hammer down and let er rip tater chip.



I usually just do what Ryan said.
 
Pump the throttle twice, leave it cracked, start.
 
Tio540, notorious for hot stars as the engine is upside down under the cowl.


Fuel pump on, idle cut off, throttle full open and crank. When she sparks and burbles, intro mixture and retard throttle. Sounds complicated but happens very fast. Once I learned the technique, I don't worry much about hot starts much anymore.
 
mtnflyr said:
full power full lean, turn the fuel pump on and start cranking, once it acts like its trying to start go to idle and full rich at the same time. time wise? i dont know. its 100 degrees out every day so...tomorrow?
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Usually what I'll do if normal start unsuccessful, or flooded engine suspected. Especially if it's a fuel injected engine.
 
Hot start issues are a function of vapor in the lines firewall forward. So it depends on the engine. Injected Lycos don't have return/purge lines, therefore you can't flush the lines with cool fuel without flooding the engine. Some Continentals do (TSIO-360 for instance), so the use of the electric pump in order to refill the line with fuel is available, which is why they are easier to start than Lycos when heat soaked. In a lyco, once the thing has heat soaked, you have to flood it in order to get it to start. Either way, you're cranking way longer than Contis, but at least the starters are hella cheaper to replace.
 
Challenged said:
What technique do you employ if you're away from your engine for just long enough that things aren't clearly cold start / hot start? How long is the amount of time?
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Just hand prop like you did cold.
 
Injected? Push enough fuel to be sure it's flooded, and then use your flooded start procedure. [IO-360]
 
In my carburated 0470, I do what mtnflyr said. Works 100% of the time.
 
hindsight2020 said:
Hot start issues are a function of vapor in the lines firewall forward. So it depends on the engine. Injected Lycos don't have return/purge lines, therefore you can't flush the lines with cool fuel without flooding the engine. Some Continentals do (TSIO-360 for instance), so the use of the electric pump in order to refill the line with fuel is available, which is why they are easier to start than Lycos when heat soaked. In a lyco, once the thing has heat soaked, you have to flood it in order to get it to start. Either way, you're cranking way longer than Contis, but at least the starters are hella cheaper to replace.
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Some injected Lycomings return fuel. Hot or cold, those engines are the ones that I think start the easiest.
 
I try normal start procedure first. If that fails, I prime first with the boost pump, just enough to budge the fuel flow gauge, then try starting again. If that fails, there is nothing to be done but wait. The flooded start procedure is not reliable; the (former) owner of PAC @ KPTK once tried a version of it that he said was sure fire. Shaka, when the walls fell. 45 minutes later, it started effortlessly with minimal boost pump priming.

Cardinal RG, IO-360 A1B6.
 
I've tried several procedures with injected Lycomings but lately I've had really good luck with:
  1. Throttle to 1000RPM
  2. Mixture to cut-off
  3. Master, mags, beacon off
  4. Don't touch anything until ready to go.
  5. When ready to go, key to start position.
  6. When the engine catches, enrichen the mixture.
The only time it's failed me so far is if I forget step #4.

Carb'd engines, I just skip priming and do everything else like it's a cold start. That's worked out mostly OK.
 
I just let the starter run a little longer to get the ITT to come down before advancing the condition lever. :)
 
Depends on the engine.

For a FI

At least for big bore continetals

I’ll hit the boost pump for a second, mixture rich, crank as I slowly advance the throttle.

Failing that, mixture ICO, throttle full, crank and when it catches throttle idle and mixture in.
 
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In my Cherokee, if it's warm or hot:

1. Crack throttle
2. mixture cut off
3. 3 to 4 shots of prime
4. Crank and advance mixture as it starts to catch.

Not to mention hot starts were about worthless on my plane until I got the mags serviced. They had 900 hours on them, got them serviced and starts way easier on hot starts.
 
Unit74 said:
Tio540, notorious for hot stars as the engine is upside down under the cowl.


Fuel pump on, idle cut off, throttle full open and crank. When she sparks and burbles, intro mixture and retard throttle. Sounds complicated but happens very fast. Once I learned the technique, I don't worry much about hot starts much anymore.
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You’re in a Turbo Lance, correct?

Isn’t that the procedure for a flooded start? After multiple failed attempts at hot starts with our Turbo Lance, this is the procedure that works every time.

Throttle 1000
Fuel Pump OFF!
Engage Starter
Slowly Advance Mixture

Starts every time.
Any other attempts, especially with the fuel pump ON, will result in a flooded engine. Hard to start.
 
my carb'd o-235 starts the same way hot or cold. non- issue in some planes and the real answer is engine/aircraft specific.
 
Wow, so much useless advice without even knowing what engine, injected or carbed. So much for internet experts.
For all you know he could be referring to his V-8 powered dildo.
 
hindsight2020 said:
Hot start issues are a function of vapor in the lines firewall forward. So it depends on the engine. Injected Lycos don't have return/purge lines, therefore you can't flush the lines with cool fuel without flooding the engine. Some Continentals do (TSIO-360 for instance), so the use of the electric pump in order to refill the line with fuel is available, which is why they are easier to start than Lycos when heat soaked. In a lyco, once the thing has heat soaked, you have to flood it in order to get it to start. Either way, you're cranking way longer than Contis, but at least the starters are hella cheaper to replace.
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The Mooney M20F with the Lyco IO-360 was a B!TCH to hot start. Flood, idle cut off, and crank away at full throttle until it caught. The Arrow with the Conti TSIO-360 is easy. Leave throttle at 1,000 RPM at shut-down. Hot start, hit the starter and after a revolution or two bring the mixture to full rich. Engine starts and idles at 1,00 RPM.
 
Let's say I'm on a cross country and I mess around in the FBO, then I go to lunch, then my wife wants to check out a local attraction for an hour..so I get back to my plane after 3 hours or so. What sort of technique would you use after 3 or 4 hours of the plane sitting? How much does ambient temperature matter? Sometimes I get behind the controls and I don't know if my go-to procedure should be cold start or hot start, that's more of what I'm interested in.
 
Challenged said:
Let's say I'm on a cross country and I mess around in the FBO, then I go to lunch, then my wife wants to check out a local attraction for an hour..so I get back to my plane after 3 hours or so. What sort of technique would you use after 3 or 4 hours of the plane sitting? How much does ambient temperature matter? Sometimes I get behind the controls and I don't know if my go-to procedure should be cold start or hot start, that's more of what I'm interested in.
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Depends on the plane/engine, and yes on ambient temperature. In my Cardinal here in VT that would be a normal semi-cold start, minimal boost pump priming then crank. I have no idea though, if that technique would need modification in the heat down South. Up here it never (or rarely) gets that hot, and when it does I'm not flying anyway.
 
Challenged said:
Let's say I'm on a cross country and I mess around in the FBO, then I go to lunch, then my wife wants to check out a local attraction for an hour..so I get back to my plane after 3 hours or so. What sort of technique would you use after 3 or 4 hours of the plane sitting? How much does ambient temperature matter? Sometimes I get behind the controls and I don't know if my go-to procedure should be cold start or hot start, that's more of what I'm interested in.
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Normal cold start for my IO-360...maybe half the prime...even if its 95 degrees..

Otherwise Hot on my Arrow is sort of Voodoo....open throttle for 20-30 seconds and then back to about half inch and crank...only after it coughs advance the mixture from the off position...

Nice write up from a guy who once owned my Arrow...

https://cheerfulcurmudgeon.com/2011/09/18/hot-starting-a-fuel-injected-lycoming-engine-io-360/
 
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A1Topgun said:
The Mooney M20F with the Lyco IO-360 was a B!TCH to hot start. Flood, idle cut off, and crank away at full throttle until it caught.….
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basically how I get it started every time in my F......ICO, NO boost pump, full throttle. usually I crank for about 5-6 seconds, then stop. then do it again and she fires up. the alternate method I've used is, like others have said, 'leave everything where it is', then instead of just going full throttle, slowly advance the throttle until it finds the mixture it likes. which usually ends up being full throttle so that's why now I just go full. so far, works every time.
 
Mags off, fuel off, throttle wide open, turn prop backwards 20+ times until the fuel stops running out onto the ground and there is no vapor coming out the exhaust.
Then fuel off, throttle closed, mags hot and yank the prop.
Repeat as necessary.
The ugly little secrets they don't mention about flying 77 year old "nostalgia" birds, when they are gushing over the glories of the taildraggers.
In Cub 159 there is no accelerator pump, no primer, and if you park it in the hot sun with the throttle closed tight and the fuel on, it will heat up and push all the fuel sitting in the lines and carb into the engine.
I recently had the chance to re-learn this valuable lesson.
 
For those fuel injected 172R/S, with everything off, try pushing throttle and mixture to full increase and count to 10 before the pre-start checklist. Then, proceed normally with the warm engine start checklist in the POH. (throttle cracked, mixture idle-cutoff, etc...). It works for me.
 
wilkersk said:
For those fuel injected 172R/S, with everything off, try pushing throttle and mixture to full increase and count to 10 before the pre-start checklist. Then, proceed normally with the warm engine start checklist in the POH. (throttle cracked, mixture idle-cutoff, etc...). It works for me.
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The point of that is to drain the fuel from HOT fuel lines, then when you crank, the lines are empty and hopefully the fuel doesn’t vaporize before getting to the injectors. You’ll see the fuel pressure drop to zero when you do this. Turn on the fuel boost pump for just long enough to see fuel pressure start to rise before turning over will save a few prop rotations.
 
Lndwarrior said:
my carb'd o-235 starts the same way hot or cold. non- issue in some planes and the real answer is engine/aircraft specific.
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One of our 152's that sports the O-235 has been having some starting issues, to what is believed to be a carb problem and this isn't the first rodeo with an issue like this since I've been there. We have to do some funny things at times to get it to light off (carb heat on- mixture rich- throttle open). It's probably about time for a carb overhaul, but once it starts, it runs fine.

With that being said, I wouldn't exactly say that an O-235 starts the same if it's cold or hot. Starting cold usually takes a couple shots of primer at the least. Hot will usually fire off by just cracking the throttle and going full rich on the mix.
 
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Challenged said:
Let's say I'm on a cross country and I mess around in the FBO, then I go to lunch, then my wife wants to check out a local attraction for an hour..so I get back to my plane after 3 hours or so. What sort of technique would you use after 3 or 4 hours of the plane sitting? How much does ambient temperature matter? Sometimes I get behind the controls and I don't know if my go-to procedure should be cold start or hot start, that's more of what I'm interested in.
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Go with the “warm” start technique on that one.....
 
Yes. Starts a hot engine in seconds. Don't care what it's for, it works. How long is your's cranking for with that procedure? 2-3 seconds with mine.

Heftiger said:
You’re in a Turbo Lance, correct?

Isn’t that the procedure for a flooded start? After multiple failed attempts at hot starts with our Turbo Lance, this is the procedure that works every time.

Throttle 1000
Fuel Pump OFF!
Engage Starter
Slowly Advance Mixture

Starts every time.
Any other attempts, especially with the fuel pump ON, will result in a flooded engine. Hard to start.
Click to expand...
 
Shepherd said:
Mags off, fuel off, throttle wide open, turn prop backwards 20+ times until the fuel stops running out onto the ground and there is no vapor coming out the exhaust.
Then fuel off, throttle closed, mags hot and yank the prop.
Repeat as necessary.
The ugly little secrets they don't mention about flying 77 year old "nostalgia" birds, when they are gushing over the glories of the taildraggers.
In Cub 159 there is no accelerator pump, no primer, and if you park it in the hot sun with the throttle closed tight and the fuel on, it will heat up and push all the fuel sitting in the lines and carb into the engine.
I recently had the chance to re-learn this valuable lesson.
Click to expand...
My 1941 Piper J4A (also 77 yrs old) w a C-85 and Marvel Schebler carb - When taxiing in shut off the fuel so the carb bowl is near empty while the engine cools down.

For immediate warm restart, turn on fuel, minimum or no prime, closed throttle, hand prop thru at least all cylinders w rich mixture w the closed throttle.

If it happens to be an immediate warm restart with a full carb bowl, switch off the ignition for shutdown. Keep everyone clear of the prop. My experience it will restart on first flip.

Whatever you do, don't allow the engine to ever become flooded.
 
I've had the best luck with the throttle-full-open-mixture-cut-off-crank-then-advance-mixture-retard-throttle technique. Seems to work well on hot, warm, etc., engines. CFI showed me that a while ago and even on cool-ish engines it works. You just have to be quick to not surge the RPM!

If you think about it it makes sense, you start very lean so that solves the whole "I flooded it" thing and with the throttle all the way open you are letting plenty of air into the engine unrestricted. Introduce fuel, you have spark, and off she should go!

Incidentally the only planes I have a hard time starting are old Archers/Cherokees.. I was told once that it has something to do with the type of magneto used? I don't think it's just me, any time I'm on the ramp and I hear people torturing the life out of a starter motor it's an older Piper. Never have an issue with Cessna's, and Conti's seem to always fire right up after one blade
 
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