Plug not firing after washing airplane

JohnAJohnson

JohnAJohnson

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JohnAJohnson
Spent three hours washing my Cardinal this morning and when I taxied back to the hangar, I noticed the #4 upper plug (right mag) was not firing at all.

I did everything I could think of to clear it, full power run at maximum lean, etc., and nothing I did could get it to fire. Plugs are fine wire Champions with 60 hours on them and I always lean to the max religiously from startup to shutdown, except for full power climbs.

To the house for lunch, 7/8 deep well, and a torque wrench... One hour later...

Pulled the plane out of the hangar and it ran up fine. No more miss. I did a bunch of run-ups and power-ups at maximum lean and couldn't get it to malfunction.

I didn't have the cowling off or spray water directly in the intakes or cowl flaps, but I did spray water forward at the bottom of the windshield and that probably introduced water into the magneto area of the engine.

Is this indicative of a problem, and if so, what is the likely area I should look at? The magneto (Bendix D-3000 on my O-360-A1F6D), or wiring from the magneto to the plugs? Or something else? Or am I worried about nothing at all?
 
I had a similar problem with a Bonanza once, every time it rained, got damp whatever there would be a miss on the Left mag. Turned out to be a bad mag...there are some mags with know water penetration issues. I sure others will chime in as it could be several different things.
 
How old is the harness, does it appear to have cracks or is the outer wrap bunched?
 
JohnAJohnson said:
Spent three hours washing my Cardinal this morning and when I taxied back to the hangar, I noticed the #4 upper plug (right mag) was not firing at all.

I did everything I could think of to clear it, full power run at maximum lean, etc., and nothing I did could get it to fire. Plugs are fine wire Champions with 60 hours on them and I always lean to the max religiously from startup to shutdown, except for full power climbs.

To the house for lunch, 7/8 deep well, and a torque wrench... One hour later...

Pulled the plane out of the hangar and it ran up fine. No more miss. I did a bunch of run-ups and power-ups at maximum lean and couldn't get it to malfunction.

I didn't have the cowling off or spray water directly in the intakes or cowl flaps, but I did spray water forward at the bottom of the windshield and that probably introduced water into the magneto area of the engine.

Is this indicative of a problem, and if so, what is the likely area I should look at? The magneto (Bendix D-3000 on my O-360-A1F6D), or wiring from the magneto to the plugs? Or something else? Or am I worried about nothing at all?
Click to expand...

Does your spark plugs have the big nut (7/8") or the small nut? (3/4") the big nut has a water seal, the small one does not. the required water to short the plug out is too small to see and it will dry its self out in about 30 minutes of run/dwell time.
 
taters said:
I had a similar problem with a Bonanza once, every time it rained, got damp whatever there would be a miss on the Left mag. Turned out to be a bad mag...there are some mags with know water penetration issues. I sure others will chime in as it could be several different things.
Click to expand...

All unpressurized mags have a atmospheric vent, water can enter freely. It's usually on the bottom of the mags, but some mags are mounted at an angle so the water can get in easier and be trapped until it gets boiled out, and leaves as steam thru the vent.
 
Tom-D said:
Does your spark plugs have the big nut (7/8") or the small nut? (3/4") the big nut has a water seal, the small one does not. the required water to short the plug out is too small to see and it will dry its self out in about 30 minutes of run/dwell time.
Click to expand...

7/8". When I pulled them last annual, I don't remember a seal. Is it an O Ring?
 
JohnAJohnson said:
7/8". When I pulled them last annual, I don't remember a seal. Is it an O Ring?
Click to expand...

No "O" ring, it's more like a red rubber plug on the end of the lead that goes into the barrel of the plug.
 
Time on/brand of mags?

Possibly no problem but it can be indicative of other issues.
 
Mag got wet. CRC Electromotive is great for drying things out. Pull the harness cap off and spray.
 
Henning said:
Mag got wet. CRC Electromotive is great for drying things out. Pull the harness cap off and spray.
Click to expand...

I don't believe a mag got wet, or all plugs on that mag would be effected. plus they don't dry out in 30 minutes.
 
Tom-D said:
I don't believe a mag got wet, or all plugs on that mag would be effected. plus they don't dry out in 30 minutes.
Click to expand...

When I had this problem it only effected 2 of the plugs according to the JPI. Eventually the thing would steam off and they would run fine..but as earlier posted there was a drainage (and a core)problem with the mag.
 
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