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Hot Starts

Releew

By Releew
in General Mooney Talk

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Releew Community Regular

Releew

Posted
Posted

As the weather is getting hotter, I am finding it more and more difficult to restart the IO-360 after even short flights.  I have had the plane for two years.  This is the second summer.  I thought I had a good sequence worked out for a hot start.... as it has worked since we purchased the plane.

 

  • Throttle indent first notch
  • Push the mixture in all the way
  • Wait a Second.....
  • Pull mixture to lean
  • Start
  • Push mixture to rich.
  • Fire
  • Throttle to idle

 

In my mind, I was breaking the vapor lock by the push and return on the mixture.  Anyway.........  That worked very well for several hot restarts....   until now.  I cannot get this engine to fire after its hot.  I have tried the POM suggestions along with forcing a flood start.  She will not fire until the engine is cooled off. (warm).  

 

  • Engine is in time.
  • Mags have less than 100 hours

Any input would be appreciated.

 

Rick

 

N201MKTurbo Grand Master

N201MKTurbo

Posted
Posted

I leave the mixture at idle cut off, throttle open to about 1000 RPM, crank till it starts, wait till it starts to falter then mixture to full rich.

Be prepared for about 100 other opinions...

  • Like 4
Cruiser Grand Master

Cruiser

Posted
Posted

Set the brakes. Set power to just above idle, mixture full rich. It should fire in two or three revolutions, wait for the engine to falter then turn on the elec fuel pump and manage the power setting

OR75 Veteran

OR75

Posted
Posted

Not sure those are real hot starts.

The hot starts I get are when the engine has been sitting for about 30 mm to an hour

Sitting on the ramp for 10 men or less to refuel for example, no problem to restart

Guitarmaster Veteran

Guitarmaster

Posted
Posted

Set parking brake.

Get out.

Fling the prop while standing on one foot and sticking your tongue out.

Turn on nav lights.

Release parking brake

Push aircraft across ramp at good clip.

Jump in

Pop clutch.

Your results may vary.

  • Like 1
Tommy Mentor

Tommy

Posted
Posted

The first thing you should do is to understand the reason for hot start being difficult (this, of course, assumes that your plane has no mechanical / ignition / electrical issues). Next, try few different methods suggested and see which one your engine likes the best. Good luck!

 

Just to hijack the discussion. One of the most common suggestions about hot start is to leave the throttle at 1000-1100 rpm at shut down. But is that at leaned-for-taxi or full mixture? Reason asking about this is because I noticed when the engine catches and mixture advanced to full, the rpm will be 600rpm NOT 1000rpm since the mixture is richer than when I shut it down. I will then quickly advance the throttle and the engine comes alive! I wonder if people's hard hot start (say it quickly 10 times) is beacuse of this?

 

Has anyone tried to set rpm at 1000-1100rpm with full mixture then cut off? Does it make it easier to hot start?

PTK Grand Master

PTK

Posted
Posted

Releew, have you tried the hot start as described in the POH?

Don's video is as per POH.

1964-M20E Grand Master

1964-M20E

Posted
Posted

I've had pretty good success with the following

 

1. set throttle to about 1300rpm +/- before shutdown, when leaned for taxi

2. for restart fuel pump on touch nothing elxe
3. crank once it fires off enrich the mixture and normal operations after that

4. also if  know I'm doing a quick turn around I will open the cowl flaps while in the pattern to dump a little more heat from the engine

  • Like 1
wpbarnar Collaborator

wpbarnar

Posted
Posted

One indication of a engine being vapor locked is: with throttle open, mixture rich and boast pump on, you will see fluxiations on the fuel pressure gage before it peaks and stabilizes. If it is not vapor locked it will peak and stabilize quickly. The fluctuations are the vapors being displace by liquid fuel. Vapor locked engines that have not been fully purged will often fire but then stumble and die.

Is this a case of just being a pain to start or just won't start? If the engine just won't attempt to fire when hot, I would suspect a coil(s) breaking down due to heat and not providing enough energy. Often the mag is overlooked when diagnosising hot start problems. Just because it ran good in flight and checks ok doesn't mean it will provide enough spark energy when it is hot and at starting RPM.

I am not familiar with the single drive mags. Does anyone know if both sides are retarded and firing during cranking or does only one side fire while cranking? If it is the later, I would really suspect the mag.

Bill

Bill

jetdriven Grand Master

jetdriven

Posted
Posted

One indication of a engine being vapor locked is: with throttle open, mixture rich and boast pump on, you will see fluxiations on the fuel pressure gage before it peaks and stabilizes. If it is not vapor locked it will peak and stabilize quickly. The fluctuations are the vapors being displace by liquid fuel. Vapor locked engines that have not been fully purged will often fire but then stumble and die.

Is this a case of just being a pain to start or just won't start? If the engine just won't attempt to fire when hot, I would suspect a coil(s) breaking down due to heat and not providing enough energy. Often the mag is overlooked when diagnosising hot start problems. Just because it ran good in flight and checks ok doesn't mean it will provide enough spark energy when it is hot and at starting RPM.

I am not familiar with the single drive mags. Does anyone know if both sides are retarded and firing during cranking or does only one side fire while cranking? If it is the later, I would really suspect the mag.

Bill

Bill

If you start it with the boost pump running or turn it on just after starting, it won't die like that. As soon as you run it a fa seconds the hot air leaves the cowling and you can turn the pump off.

Watch your fuel pressure gauge next time you hot start it. It dips to 13 PSI and often below.

  • Like 2
Oldguy Veteran

Oldguy

Posted
Posted

A couple of us with J models over in Alabama (about as as hot as NOLA) have a technique which seems to work with a fair amount of consistency:

 

1. Throttle to ~1200 RPM prior to shutdown.

2. Pull mixture to shutdown.

3. To restart - do NOTHING to mixture or throttle prior to turning the key.

4. Once you start cranking, smoothly advance mixture as it starts. Should fire on 4 blades or less.

 

One caveat, though: we all have Sky-Tec startes which seem to spin the engine fairly fast.

 

This seems to work for us anywhere from a 10 minute fuel stop to an hour's layover, but as with any advice, YMMV.

 

John

  • Like 3
DaV8or Grand Master

DaV8or

Posted
Posted

M20S Driver recently posted this; it's a YouTube video of Don Maxwell doing hot starts on the Lycoming. Hope this helps:

"I just saw this on a link from MAPA..

https://www.youtube....h?v=jbRYqS-fRo0

This is on a Lycoming engine. Is it the same on io-550?

He makes it look so easy :)

Driver"

 

Yeah, his hot start video is kinda lame. I wish he would make one with him shutting down then waiting about 30 minutes and then try starting. It's a whole other ball game IMO.

  • Like 1
DaV8or Grand Master

DaV8or

Posted
Posted

What has always worked well enough for me is-

 

Taxi lean

1400 RPM

Idle cut off

Don't touch anything!!!

Boost pump to get up to pressure then off. (although I may try leaving it on after reading this thread)

Crank and when she starts to fire, mixture in.

Reduce to 1000 RPM.

  • Like 1
Vance Harral Veteran

Vance Harral

Posted
Posted

Yeah, his hot start video is kinda lame. I wish he would make one with him shutting down then waiting about 30 minutes and then try starting. It's a whole other ball game IMO.

 

Agreed.  The first start in the video is interesting/useful, though he doesn't say exactly how long it's been shut down.  All the subsequent starts, that are less than 2 minutes after the prior shutdown, not so much.

 

Not intended as a knock on Don, my guess is he does well with 30-minute turnarounds, too.  But that's not what's shown in the video.

Releew Community Regular

Releew

Posted
  • Author
Posted

Well.....  I had the opportunity to test a combination of a few of these suggestions this week on a fight to Baytown Texas from Abita Louisiana.  About 1.5 hours......  

 

  • On Downwind Cowl Flaps Open
  • Before shutdown throttle back to ~1200RPM (Keep in position)
  • Pull the Mixture

 

Waited a minute.... (She was hot!)

 

  • Throttle was in previous shutdown position (~1200 RPM)
  • Hit the key
  • Spun ~4 times (blades)
  • Fire
  • Worked the mixture like the throttle until engine smoothed out
  • Reduced to idel

 

Tried the same procedure on the return trip and did a double restart.......  Effortless both times!  Sure hope this continues to work.

 

Thanks everyone....

 

Rick

  • Like 2
jlunseth Grand Master

jlunseth

Posted
Posted

Hot starts in my 231 are effortless, but the plumbing is different than in the Lyc's so there is no point in describing what I do. The one thing I can add is that I discovered some time ago that the judicious use of the high boost pump will cure quite alot. On start, the engine will fire and run just a little bit, then quit. That is because there is vapor in the lines and the engine cannot get a consistent flow. I can prime and try again, but it takes several efforts to start the engine that way (by priming and restarting) and hitting the prime button while starting does not always work either. The problem is that the fuel flow is not consistent because of the vapor locking in the fuel line. Now what I do, is push the high boost button as soon as the engine fires and hold it on for a couple of seconds. My high boost has a safety blocking it, so if I wanted to turn it full on I would need to move the safety aside and press the rocker switch on. Instead, if I just push the top of the rocker with the safety in place the high boost will come on momentarily, pushing fuel through the lines until the engine can fully catch and the engine fuel pump is working. I don't do this any longer than necessary or I would flood the engine.

Don't know if that will help you Lyc guys, but it sure works in my engine.

Guitarmaster Veteran

Guitarmaster

Posted
Posted

Changed my technique a little after reading this. Adding the boost pump makes no more stalling on the first attempt at hot-start.

Sent from my iPad using Tapatalk

jetdriven Grand Master

jetdriven

Posted
Posted

Do you guys read the thread before repeating the same thing twice in a row? It seems like half of the threads on here ask something that's been described, hashed to death, and dealt with 3 threads before as well. Sorry to be a prick, But we literally have 5 threads each running to several pages about cam failure, whether LOP burns valves or not, how to run LOP, why camguard sucks, why retreads won't fit in the wheel well, why bladders suck, and the merits of 25 square climbs.

If you start it with the boost pump running or turn it on just after starting, it won't die like that. As soon as you run it a fa seconds the hot air leaves the cowling and you can turn the pump off.

Watch your fuel pressure gauge next time you hot start it. It dips to 13 PSI and often below.

DaV8or Grand Master

DaV8or

Posted
Posted

Do you guys read the thread before repeating the same thing twice in a row? It seems like half of the threads on here ask something that's been described, hashed to death, and dealt with 3 threads before as well. Sorry to be a prick, But we literally have 5 threads each running to several pages about cam failure, whether LOP burns valves or not, how to run LOP, why camguard sucks, why retreads won't fit in the wheel well, why bladders suck, and the merits of 25 square climbs.

 

 

OK... what do you want to talk about? There are a lot of new and excited people here. They haven't been there and done that yet. Their questions are to be encouraged and answered IMO. If you don't want to deal with it that's understood, but why harangue them?

 

There are but so many topics and a much smaller sub set are popular.

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