Hot Starts

[C170U2]

It was my sons birthday this weekend, so we took a bunch of his little friends up flying. I ferried about 8 loads of kids up and around the airport. Once the engine got hot she seemed to not start as easily. Towards the end, I was also dealing with a drained battery due to forgetting to polarize the generator.

My question is, do you do anything different when starting an engine that is already hot? I didn't prime or pull the prop through. All I did was throw on the mags and pull the starter.

[dunlaps3]

Most of the time when I give rides and I know that I will restart in just a few minutes , as I taxi in I have the engine at idle power , then I shut it off with the key.
Now the fuel mixture is still perfect and when I hit the starter , it pops off in less than one revolution. I have done this for years with all types of piston power airplanes.
Now Turbines , well , better off not shut 'em down ! Andrew

[C170U2]

Makes sense, I'll try it next time!

Thanks.

[Kyle Wolfe]

I do the same and shutdown with the key if I'm going to start again soon. As a result it starts on the first blade.

[minton]

I do the same and shutdown with the key if I'm going to start again soon. As a result it starts on the first blade.

OR; Kicks through went you least expect it!

[GAHorn]

I suppose a "stickler" for procedure might point out that shutting down with the key is not the factory recommendation (and I think we all know why the factory does not approve that technique... safety.)

I always push the throttle one full stroke, then open it 1/4" when starting hot and have not had any problem.

[C170U2]

Ok...I'll take the bait. Why not shut it down with the ignition? My 120 has no mixture control and I always shut down with the mag switches and have never had any issues (If anything it tells me that the mags are not hot). I suppose I could shut it down with the fuel shutoff but I rarely do that.

[Ryan Smith]

I would assume because when you shut down with a key, there is still fuel in the cylinders that isn't burned off. When you bleep down with mixture, it starves the engine of fuel. No fuel, no fire, no run. All you're missing with fuel in the cylinders (shutting off with mags) is a tiny spark. I've heard of guys advocating shutting down with mags vs mixture periodically to verify that the mags will, in fact, shut the engine down to indicate that there isn't a hot mag.

I was shocked to learn that not all airplanes have a mixture control when I got checked out in my uncle's J3 at age 13.

[Kyle Wolfe]

Minton what do you mean by kicks through when you least expect it?

I always lean it to kill it when shutting down and don't plan to restart in the next few minutes. Just saying I've found it easiest on my starter and blood pressure to use the mag grounding approach when I have a hot start coming. Each of us finds a process that works - and was adding my experience to give the poster an option.

And George, you do always check your switch by turning it off then on before shutting down to ensure you don't have a hot mag, don't you?

My dad's good friend still has a limp from the time following an annual he turned the prop through to check compression prior to flying and the 170 started - with the keys in his pocket!

[GAHorn]

...
And George, you do always check your switch by turning it off then on before shutting down to ensure you don't have a hot mag, don't you?

My dad's good friend still has a limp from the time following an annual he turned the prop through to check compression prior to flying and the 170 started - with the keys in his pocket!

I check my magneto switch regularly, and every time I change oil as part of my return-to-service checks.

[bagarre]

What about the mag check during your run up ?
The rpm drop indicates the mag grounded properly.

I've never had an issue with hot starts and only need to prime a few shots if it's below 40 degrees.

Funny, I have the opposite problem as it won't shut down once warmed up. The mixture cut off is against the stop but it keeps chugging as it pulls a little more gas I end up pushing the throttle in a little to get it to quit. My carb could use a good going over.

[n3833v]

I have shut off with the key to check mags but follow immediately with mixture as regular shut down procedure. Correct me if this is a no-no.

John

[johneeb]

What about the mag check during your run up ?
The rpm drop indicates the mag grounded properly.

I've never had an issue with hot starts and only need to prime a few shots if it's below 40 degrees.

Funny, I have the opposite problem as it won't shut down once warmed up. The mixture cut off is against the stop but it keeps chugging as it pulls a little more gas I end up pushing the throttle in a little to get it to quit. My carb could use a good going over.

David, You could also check your primer it may be leaking internally.

[daedaluscan]

I was taught to do a live mag check every time I shut down, and then full lean. I fuel up after I fly and always do this, then I pump of throttle and she always starts on the first blade.

[minton]

I was taught to do a live mag check every time I shut down, and then full lean. I fuel up after I fly and always do this, then I pump of throttle and she always starts on the first blade.

That seems to be the accepted procedure. Carbon hot spots can cause kick through as well as hot mags. I can't see going outside of accepted procedures when bad things can come of if. Just my opinion