Clearing fouled plugs.

[Plow King]

Hey all

Have just been re-reading the "Tips on engine care" put out by TCM, and under the section Ground Run-up (reprinted from the Aviation Mechanics Bulletin) I came across this piece of advice:

11. Never but never attempt to "burn out" a magneto drop with a ground run-up. This "time honored" procedure succeeds only at the expense of the engine's mechanical health.

This was news to me, but it has made me reconsider how I handle such situations.

Would anyone with any knowledge on the subject care to comment

Cheers

PK

[ForkTailedDrKiller]

I am guilty of "clearing a fouled plug" on many an engine over the years by the time honoured method of leaning during a runup.

However, since taking the Chimbu Chuckles Master Class on Engine Managment, which advocates heavy leaning of an idling engine during warm up, I have never had a problem with plug fouling on IO520 in the FTDK!

Dr :8

[The Green Goblin]

I agree FTDK, aggressive leaning on taxi so that if you try to take off without en-richening the mixture the engine will not rev. This prevents damage if you inadvertently take off with the mixture lean also.

[Plow King]

Thanks FTDK. I see where you're coming from, I've just been skimming over some old threads, particularly this one:

Mixture Rich for Taxi (http://www.pprune.org/dg-p-general-aviation-questions/249794-mixture-rich-taxi.html)

PK

[Fred Gassit]

Sometimes it is lead fouling that causes the problem-you can rev the sh*t out of the engine until the sun burns out then and wont normally fix the problem. Plugs fouled with carbon usually clear readily enough.

The lead scavenging agents in the fuel need a minimum temp to function, which you wont get at idle power settings, need about 1200rpm minimum, more than your flight instructor likes but hey...

Also leaning when taxiing as others suggested, which is more about the carbon buildups than the lead.

Would TCM have been warning against high power settings on a badly running engine because of the cylinder pressures involved while it is popping and farting away? I dont know.

[rioncentu]

I concur with Dr.

Since being shown to lean aggresively on the ground, I have never had a fouled plug.

Pick up the plane from the LAME's and sure enough, fouled plugs from them taxiiing around full rich.

But be sure to lean VERY aggresively so you can't takeoff with a part lean mix.

How do I know about that :eek:

[Jabawocky]

And let me add to that, as part of my retract flaps, fuel pump off.....mixture LEAN as I taxi away from the runway, because thats another time to foul them and another litre of fuel saved!:ok:

[blackhand]

but it has made me reconsider how I handle such situations.

Try this:
Run engine up to prop governor operating speed, cycle the prop two or three times.
Don't be afraid to load the engine up. This should clear spark plug quicker than leaning out the mixture.

Cheers
BH

[ReverseFlight]

I'd say taxi on lean as a prevention but run up the engine as a cure.

[Tankengine]

A squillion years ago when I was a GA instructor, BP was worse than Mobil worse than Shell[LL].
Any Ideas?:confused:

Lean taxi is a very good idea.:ok:

If a runup to 1700-1800 does not quickly fix then at least it should clean the top plugs.:ok:
grab a few tools and replace/clean the bottom plugs.:ok:
[if gen Y will get dirty]

[mcgrath50]

Please Tankengine, I'll pay one of you old blokes to do it now you all don't have the reflexes or eye sight to fly :}

[Tankengine]

Yeah, whatever!:E

If you pay to get your first Job you can pay me to change your plugs!:ugh:

I will charge you my usual pay : $237.03 PH with a min 5.30Hr/day + traveling time at same + about $162 per day food!:E:E

And being so old i'm real slow!:)

[mcgrath50]

:ok: Not all Gen-Y is like that, just like everyone not in Gen-Y isn't useless and old, I know a lot give us a bad name here!

[Tankengine]

"Not all Gen-Y is like that, just like everyone not in Gen-Y isn't useless and old, I know a lot give us a bad name here! "

How true!:ok:
Off next week to instruct some teenagers, [Gen Z??:confused:]
Some useless, some really good!:)