Hot start procedures for IO-360

[KB4]

17 hours ago, OR75 said:

Hot start: full throttle , mixture full lean then crank , full reach and throttle back when the engine starts then lean 

Always had no problems with Maxwell technique til I didn’t.  after 15 minutes sitting didn’t fire up immediately like usual. Tried the above and instantly worked.  Another good tool.  

[PT20J]

4 minutes ago, KB4 said:

Always had no problems with Maxwell technique til I didn’t.  after 15 minutes sitting didn’t fire up immediately like usual. Tried the above and instantly worked.  Another good tool.  

Throttle controls air, mixture controls fuel. If it takes full throttle (lots of air) you somehow flooded it during earlier attempts.

Sometimes when an engine won’t start, it is difficult to know if it has too much fuel, or not enough. In this case, it is best to get it to a known condition and then use the appropriate technique. Since you cannot remove fuel (except by waiting for it to evaporate which isn’t always practical), you can purposely flood it and then use the flooded start procedure. Don’t over do it - you don’t need raw fuel puddling on the ground and dripping out the exhaust creating a fire hazard.

Skip

[KB4]

In my case, no need to purposefully flood my IO360 that is already taken care of for me the second I shut down I can hear it in the spider. 

[ZuluZulu]

Should add, I have also had no fouling problems with my massives due to using aggressive leaning technique on the ground.  I lean it so much that I sometimes have to add a little mixture to prevent the engine dying when I try to break standing inertia.  And that's within a wide range of conditions from near-freezing temperatures (Big Bear) to mid-110s (Palm Springs).  

[Shadrach]

7 hours ago, PT20J said:

Throttle controls air, mixture controls fuel. If it takes full throttle (lots of air) you somehow flooded it during earlier attempts.

Sometimes when an engine won’t start, it is difficult to know if it has too much fuel, or not enough. In this case, it is best to get it to a known condition and then use the appropriate technique. Since you cannot remove fuel (except by waiting for it to evaporate which isn’t always practical), you can purposely flood it and then use the flooded start procedure. Don’t over do it - you don’t need raw fuel puddling on the ground and dripping out the exhaust creating a fire hazard.

Skip

I’ve seen two Mooneys catch fire because a ham fisted pilot failed a hot start and elected to flood the engine and use the flooded start procedure. One blew out when the engine started and the other was put out with a fire extinguisher. 

If the pilot has fumbled the start so badly that they’re at this point, it might be better to walk away for a bit allowing the starter and battery to have a break. Come back after 30 minutes and try the flooded start procedure (note that I didn’t say flood the engine). If that fails then go to a cold start procedure.

Incidentally, if anyone is ever AOG with a failed boost pump, a cold engine will start easily in cool weather without prime. Set throttle to 1/4”, full rich and crank. It will typically fire in five to six blades.

Edited September 23, 2021 by Shadrach

[A64Pilot]

17 hours ago, Shadrach said:

I’ve seen two Mooneys catch fire because a ham fisted pilot failed a hot start and elected to flood the engine and use the flooded start procedure. One blew out when the engine started and the other was put out with a fire extinguisher. 

If the pilot has fumbled the start so badly that they’re at this point, it might be better to walk away for a bit allowing the starter and battery to have a break. Come back after 30 minutes and try the flooded start procedure (note that I didn’t say flood the engine). If that fails then go to a cold start procedure.

Incidentally, if anyone is ever AOG with a failed boost pump, a cold engine will start easily in cool weather without prime. Set throttle to 1/4”, full rich and crank. It will typically fire in five to six blades.

A Maule was burnt up at Brown’s Sea Plane base a few years ago, normally people won’t choose an injected airplane for a  float plane as if you cast off and are floating downwind you may need to start now.

Anyway the Instructor was teaching to flood the hot motor and then do a flooded start under the theory if you started from a known condition it would be faster.

So as you say, don’t do a flooded start on purpose, the outcome may not be what you wanted

[Will.iam]

This very good info for a lycoming engine but i noticed a couple of posts that said continental engines have a fuel return line and are on the bottom so do not get as much heat. Are the procedures different for hot start on continentals? I have heard of one procedure to just run prime pump for 1 min with mixture full closed as the fuel will be pumped through the lines via the fuel return line thus cooling the lines and removing any air from vaporization. Will the technique of starting with full lean and then once the engine starts to goto full rich work when the engine hasn’t been purposely flooded? My engine fuel pump seems to lag getting pressure back up or maybe its pushing the vaporized air through before the engine dies from the initial start and then i have to prime and start again. Sometimes if I’m fast enough with a shot of primer i can keep engine going long enough for the engine pump to keep a steady supply going. I’d never thought to try starting with mixture in cutoff will have to give this a go next time. 

[flyboy0681]

There are so many postings here that it leads me to the conclusion that there is no simple, one size fits all solution or technique to this problem. The only thing that I can add is that the age and wear on the engine could have something to do with it because prior to my overhaul it was a bitch getting her to turn over during a hot start. After the overhaul she turns right over no matter how hot she is or how long she has been sitting, even if only ten minutes for a fuel stop.

[A64Pilot]

3 hours ago, Will.iam said:

This very good info for a lycoming engine but i noticed a couple of posts that said continental engines have a fuel return line and are on the bottom so do not get as much heat. Are the procedures different for hot start on continentals? I have heard of one procedure to just run prime pump for 1 min with mixture full closed as the fuel will be pumped through the lines via the fuel return line thus cooling the lines and removing any air from vaporization. Will the technique of starting with full lean and then once the engine starts to goto full rich work when the engine hasn’t been purposely flooded? My engine fuel pump seems to lag getting pressure back up or maybe its pushing the vaporized air through before the engine dies from the initial start and then i have to prime and start again. Sometimes if I’m fast enough with a shot of primer i can keep engine going long enough for the engine pump to keep a steady supply going. I’d never thought to try starting with mixture in cutoff will have to give this a go next time. 

Big Conti’s don’t have the vapor lock issue Lycomings have, as you say you can run the boot pump and fuel will flow though, another difference is after start if a Conti starts to quit due to lean mixture you can hit the boost pump momentarily and it will pick right up again.

 

[Will.iam]

21 minutes ago, A64Pilot said:

Big Conti’s don’t have the vapor lock issue Lycomings have, as you say you can run the boot pump and fuel will flow though, another difference is after start if a Conti starts to quit due to lean mixture you can hit the boost pump momentarily and it will pick right up again.

 

So since they don’t have the vapor lock issue does that mean they also don’t leak out fuel into the cylinder so it's not in a flooded state like the lycomings is? (With freshly overhauled mag and a surefly ignition I’m hoping hot hard starts will be a thing of the past)

[A64Pilot]

Just now, Will.iam said:

So since they don’t have the vapor lock issue does that mean they also don’t leak out fuel into the cylinder so it's not in a flooded state like the lycomings is? (With freshly overhauled mag and a surefly ignition I’m hoping hot hard starts will be a thing of the past)

My experience with them in South Ga and Fl heat is that they don’t flood like a Lycoming, but how tight the cowling is I believe also has an effect, the C-210 I used to fly hot starts weren’t as issue, difference between it and a cold start was if hot you didn’t need to prime, just start at high idle and full rich, cranked like a car, no drama, no quick hand movements pulling and pushing anything.

That’s a Cessna, a Mooney may be different, I notice my neighbor has issues starting his Bonanza, you always hear it crank and go to high RPM immediately, either he doesn’t know what he’s doing or a Bonanza is way different than a Cessna? But this guy pumps the throttle on a cold start too, I’ve shown him all he needs to do is a short boost pump run, I think he thinks it has an accelerator pump?

[Shadrach]

On 9/23/2021 at 3:05 PM, flyboy0681 said:

There are so many postings here that it leads me to the conclusion that there is no simple, one size fits all solution or technique to this problem. The only thing that I can add is that the age and wear on the engine could have something to do with it because prior to my overhaul it was a bitch getting her to turn over during a hot start. After the overhaul she turns right over no matter how hot she is or how long she has been sitting, even if only ten minutes for a fuel stop.

First we would have to acknowledge what the problem is. The only time that I’ve had a hot start problem, it was related to an ignition issue. I have an injected lycoming.  It starts reliably when hot. It starts reliably when cold. It starts reliably in when in between. It starts reliably after running for three minutes to the fuel farm. None of these starts require a complicated procedure.  It’s binary. To prime or not to prime, that is the question.  I do not believe that my engine is special. I was flying behind an AEIO320 for a while.  It had slick mags with an impulse coupling rather than Bendix and SOS. Nevertheless, it responded the exact same way my IO360 does.   My personal experience suggests that  hot start problems are either maintenance related or from overly complicated “techniques”. 
We like to anthropomorphized aircraft. “She’s temperamental when she’s hot”... In reality, fuel, air and spark typically respond in a very predictable manner.

Edited November 22, 2021 by Shadrach

[jaylw314]

2 hours ago, Will.iam said:

So since they don’t have the vapor lock issue does that mean they also don’t leak out fuel into the cylinder so it's not in a flooded state like the lycomings is? (With freshly overhauled mag and a surefly ignition I’m hoping hot hard starts will be a thing of the past)

I expect ALL fuel injected motors will leak some fuel into the intake manifold (not the cylinders, I don't think we have direct fuel injection in general aviation), since the differences between the continental and lycoming only matter up to the fuel divider.  The fuel lines past the divider should be, for most purposes, pretty much the same, and will leak fuel when they heat up.

[Shadrach]

28 minutes ago, jaylw314 said:

I expect ALL fuel injected motors will leak some fuel into the intake manifold (not the cylinders, I don't think we have direct fuel injection in general aviation), since the differences between the continental and lycoming only matter up to the fuel divider.  The fuel lines past the divider should be, for most purposes, pretty much the same, and will leak fuel when they heat up.

All the aero diesels are DFI.  Agree they are similar in principal. One difference between the Bendix RSA and Continental is that the fuel return on the Continental allows cool fuel to be circulated to the servo by running the boost pump with the mixture at idle cut off.

[jaylw314]

13 minutes ago, Shadrach said:

All the aero diesels are DFI.  Agree they are similar in principal. One difference between the Bendix RSA and Continental is that the fuel return on the Continental allows cool fuel to be circulated to the servo by running the boost pump with the mixture at idle cut off.

Ahh, good point, I forgot about the diesels!

[Will.iam]

3 hours ago, Shadrach said:

First we would have to acknowledge what the problem is. The only time that I’ve had a hot start problem, it’s was related to an ignition issue. I have an injected lycoming.  It starts reliably when hot. It starts reliably when cold. It starts reliably in when in between. It starts reliably after running for three minutes to the fuel farm. None of these starts require a complicated procedure.  It’s binary. To prime or not to prime, that is the question.  I do not believe that my engine is special. I was flying behind an AEIO320 for a while.  It had slick mags with an impulse coupling rather than Bendix and SOS. Nevertheless, it responded the exact same way my IO360 does.   My personal experience suggests that  hot start problems are either maintenance related or from overly complicated “techniques”. 
We like to anthropomorphized aircraft. “She’s temperamental when she’s hot”... In reality, fuel, air and spark typically respond in a very predictable manner.

Yes this is why I’m really looking forward to how the warm starts are after i have the electronic ignition. Should alleviate most of my problems. 

[Ragsf15e]

52 minutes ago, Will.iam said:

Yes this is why I’m really looking forward to how the warm starts are after i have the electronic ignition. Should alleviate most of my problems. 

Don’t expect miracles.  Yes a SF starts well, but if you don’t use the well developed hot start technique, it won’t start.

[carusoam]

M20Ks have a variety of fuel priming plumbing…

It helps to really know your specific system…

where the fuel goes when priming…

where the fuel goes with the fuel pump running, at idle cut off…

Where the fuel goes when you hear the bubbling under the cowling…

The fuel selector valve is pretty complex in Continental powered Mooneys…. At ICO, the fuel gets returned somewhere…

In Ovations the fuel returned goes to the same tank it came from…

Ovations don’t usually get hot starts, unless it is a really Quick turn from flying to stopping at the fuel pump…

It is really cool to be able to run cool fuel through the lines… taking out a serious variable…

Pp thoughts only…

Best regards,

-a-

[Shadrach]

19 hours ago, A64Pilot said:

the C-210 I used to fly hot starts weren’t as issue, difference between it and a cold start was if hot you didn’t need to prime, just start at high idle and full rich, cranked like a car, no drama, no quick hand movements pulling and pushing anything.

What you’ve described above is precisely how my Lycoming IO360 behaves. If the engine has been run in the previous four hours (regardless of how long it was run), I simply turn the key and provide fuel when it starts. If it fails to start, then I know there is inadequate adequate fuel in the manifold to support combustion. When that happens, I simply give it a short prime.  
One thing I may do differently than others is prime at WOT. Priming with a throttle closed will require running the boost pump longer.

[PT20J]

13 hours ago, Ragsf15e said:

Don’t expect miracles.  Yes a SF starts well, but if you don’t use the well developed hot start technique, it won’t start.

THIS^^^^

The hotter spark during cranking may slightly widen the range of mixtures over which the engine will fire, but you still need sufficient fuel mixture of the right proportion to air to start, and that’s what the hot start procedure accomplishes.

Skip

[Shadrach]

On 9/21/2021 at 10:04 PM, ZuluZulu said:

FULL throttle?  Your poor brakes!

A full throttle start might be hard on an engine if it’s allowed to reach high RPMs before the throttle is retarded (There’s an SR22 on my hanger row that breaks 2000 RPM every single time it’s cold started). However, given that the brakes are locked they are not affected in the least. No heat = no wear...

Edited November 22, 2021 by Shadrach

[PT20J]

8 minutes ago, Shadrach said:

One thing I may do differently than others is prime at WOT. Priming with a throttle closed will require running the boost pump longer.

This is a good point. It’s fastest and more precise to prime with the RSA fuel injector off the idle circuit. Anything past about 1/4 throttle will do it. 

Skip

[Shadrach]

1 minute ago, PT20J said:

This is a good point. It’s fastest and more precise to prime with the RSA fuel injector off the idle circuit. Anything past about 1/4 throttle will do it. 

Skip

I agree. But priming with the throttle against the stop takes a variable out of the process. It ensures that everything is the same for every prime with the exception of engine temperature and OAT.

[Mooney217RN]

I'm a bit late to the party on the responses here, but I was given a hot start technique 20+ years ago from Tom Rouch (Top Gun) and he was spot on.  I put about 2,000 hrs on the IO-360 and never had a hot start issue.  In fact, I could more easily hot start it as opposed to a cold start.

Simple procedure - Throttle about 1/3 open, mixture lean/cutoff.  Crank it, add mixture smoothly but quickly as the engine fires.  works every single time.

[ArtVandelay]

This is a good point. It’s fastest and more precise to prime with the RSA fuel injector off the idle circuit. Anything past about 1/4 throttle will do it. 
Skip

To be clear is that a 1/4” or a 1/4 travel.


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