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hot start procedure

F

fazlo

Member
I am trying to figure out what my hot start procedure should be on my O-320 (fitted on my RV4) and perhaps you can help me out.

Yesterday, I tried to start my engine 5-6mns after having it off (with mags off rather than leaning as I intended to restart shortly), no priming, fuel pump on, ? inch throttle : it started for 1 second and then died. Couldn?t restart it.

5 mins later after ventilating the engine (mags off, fuel off, full throttle,10 turns of prop manually opposite) still nothing.

1hr later ventilating again, little bit of priming and it finally started.

Some guys told me that it is a fairly common feature: when the engine is switched off, the heat of the magnetos actually increases, sometimes to a level where they become inoperative. The heat of the engine would actually be transferred to the magnetos when they are no longer cooled by their special venting?Does this make sense?
What?s the best advice for carburetted O-320 hot start procedure?

Olivier, France
RV4, G-RVDP
 
It died after a second because it flooded. If this happens, you can either wait a few minutes and try again, or if you want to save your starter, shut off the mags, pull the mixture, open the throttle fully, get out and pull the prop through about 10 blades. Then get back in the plane and start it normally, only open the throttle a little more than what you'd open it when doing a normal start. Just pull the throttle back as soon as it fires. If you have a separate starter button from the mags, you could also do this same routine from inside the airplane by cranking the engine a few blades with the throttle open before doing it with the mags on. In general for hot starts with a carb, you'll probably need to open your throttle a little more than for a cold start. If it starts and dies, then try as described above. If you have an integrated starter/mag switch, then you can do it from inside the plane, then just turn it over a few blades with the throttle open and the mixture out, then push the mixture in and hope it goes. :)
 
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That must be Dudley Patterson's old RV-4 - very nice.

My hot technique on a carburetted O-360 RV-4 is to set mixture to ICO and throttle wide open. When the engine fires move the mixture to rich and bring the throttle back. If it doesn't catch and run, you will have blown out most of the excess vapour and a normal cold start setting will probably work.

This technique always seems to work for me, but it assumes you are dealing with heat soak in the fuel lines etc and excess fuel vapour. I've not heard of heat problems with mags, but maybe worth checking mags, timing, wires and insulation etc.
 
Thx for replies and advices. So, if one's ennemy in hot starting is flooding, then it is silly to switch off with mags and one would be better off starving to ease re starting?
(Mark, yes, it's Dudley's, he's done a very nice job!)
 
fazlo said:
I am trying to figure out what my hot start procedure should be
Click to expand...

This has worked for me every try (so far).

1) Mixture off
2) Throttle idle
3) Fuel pump on for 5-10 seconds & then off
4) Throttle open 1/4"
5) Start prop turning with the starter and slowly push in the mixture....... When she likes it she'll start!

Also, you might check your Mag timing. Strangely enough, I have found that the closer to 25 deg BTDC and the closer to "in sync." my mags are the easier my engine is to start (hot or cold).

Hope this helps,
 
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twsurveyor said:
This has worked for me every try (so far).

1) Mixture off
2) Throttle idle
3) Fuel pump on for 5-10 seconds & then off
4) Throttle open 1/4"
5) Start prop turning with the starter and slowly push in the mixture....... When she likes it she'll start!

Also, you might check your Mag timing. Strangely enough, I have found that the closer to 25 deg BTDC and the closer to "in sync." my mags are the easier my engine is to start (hot or cold).

Hope this helps,
Click to expand...

Im going to give this one a try. I have always shut down with mixture to ICO.

On HOT restart, I would use full rich, boost pump on a few secs, then start to crank engine and pump the throttle in/out until it starts. This would work well for me on a cold start, Hot start 50/50. :mad:

Im going to try your 1/4 throttle and slowly move mixture in until it starts.
If that doesnt work, i guess i have boiling fuel or Heat soaked mags.
 
This "slowly pushing in mixture" trick for hot restart has never let me down since Tommy indicated it! (touch wood) Thank you very much!!!
 
Just something I noticed here, but a few folks are talking about different things I think....proc's for Injected and Carb'd engines aren't necessarily the same at all. For example, running the fuel pump on a Carb will do little other than to maybe fill the bowl. Doing that on an injected engine puts fuel into the cylinders - unless you have a purge valve, then the process changes yet again, as it does depending on which injection system you have, which ignition you have, impulse couplings, starter, etc... This is sort of like the primer debates of old, each engine is sort of like a girl. You need to learn their individual nuances, because my experience with lyco's is that if one thing is absolute, it's that they all are different. Sure some general methods will help, but details will just need to be figured out.

I do know one rather famous RV driver who flies a lot of different airplanes...and his procedure for hot starts in an unkown plane is just to flood it, then start it from there because at least every time you know where you're starting from! :)

Just my worthless 2 cents as usual.

Cheers,
stein
 
SteinAir said:
I do know one rather famous RV driver who flies a lot of different airplanes...and his procedure for hot starts in an unkown plane is just to flood it, then start it from there because at least every time you know where you're starting from! :)
Click to expand...

Just remember the procedure for putting out the resulting intake fire. :rolleyes:
But hey, it is good for washing the oil from the cylinder walls and the cool noise it will make when the fuel torches off in the exhaust system. :eek:

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
This hot start procedure always works for my carb 0 320 with electronic ignition.
Pump the throttle full in then out once (this pumps fuel from the accelerator pump). Crack the throttle slightly open then crank. The engine always starts within a few blades and immediately settles down to a steady idle.

Fin
9A
 
Caution on pumping carb throttles

Most of the students I taught stepped blindly through the checklist for starting carburetor equipped lycomings. Pump the throttle three times, then continue on with the checklist until it said "engage starter".

Meanwhile, the excess fuel would drip out of the upside down carburetor into the air intake duct. One backfire and it is time for the fire extinguisher.

One unfortunate instructor and student had a backfire and filter fire but didn't know it. Passing through a marine layer at 1000 feet the engine quit after ingesting burned filter and ducting. They survived the forced landing in a field.

If you are going to pump the throttle and make use of the accelerator pump, please only do so WHILE the engine is cranking so all the unburned fuel goes where it is supposed to... inside the engine cylinders. It's STARTER then PUMP, not PUMP then STARTER.

Sorry for the thread drift from "how to start" to "how not to start".

Don
 
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