What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Spark mag wires coming off inflight

A

APACHE 56

Well Known Member
Has anyone had trouble with the spark plug wire boots pulling off from the Pmag barrels (is that the correct term)? When I returned from a flight today I found that 3 of the 4 wires had come off the right mag. Looks like a combination of normal engine vibration and the squeezing force of the boots conspire to pull them off. The mechanical post/sleeve connector isn?t very strong. These are the 90 degree automotive type wires.

Any good ideas on how to fix this issue?
 
This was one of my concern when I installed my PMAG with automotive type plug. I was assured that is not an issue and it has not been so far.

You may want to move them to the top plugs.
 
I had heard that getting a good, ositiv elock requird some care, and it does! I am always careful to make sure I hear a "click" when in stalling them, and then I "burp" the boot to get the air out and hep it sit down on the plug. Failure to get the positive click, and leaving air in the boot, can cause them to pop off.
 
NOT YET

G'day folks,

I think that Apache 56 is talking about the leads coming loose on the PMag itself not the spark plugs.

I have a E/Pmag combo, 3 years, and have not yet had the leads come loose at the E/Pmags.

Also watching for them to come off the plugs, so I am particular about the 'click', and air in the boot too - I use a very small slot screwdriver with a smoothed blade that I have had for years in the car tool kit.

Regards,
 
Never had one come off but I am also very picky about hearing the click when installing.

Even when trying to remove them sometimes it is difficult because the boot tends to grab/stick/suck onto the post.
 
As noted on a previous thread

Ted RV8 said:
We used to put a tie wrap around the boot to tighten the friction on high vibration race engines.

Works great as long as the boot and spark plug have no oil on them. Add oil and it's kinda like a wet watermelon seed.

Ted
Click to expand...
 
It's the wire to mag not wire to plug.....

Bob Redman said:
G'day folks,

I think that Apache 56 is talking about the leads coming loose on the PMag itself not the spark plugs.
,
Click to expand...

Yes Bob that is correct. I have cleaned the "barrels" with brake cleaner to get any/all the moisture and oil removed. Since the barrels are molded plastic I imagine they are tapered so the tie wrap won't work.

I may try the Magnecor (suggestion above) custom wires assuming they can accommodate the Pmag form.

VR,
Don
 
My mistake on the end Apache was talking about....but my experience is the same on both ends - you need to be very careful to get the click, and you have to burp the rubber cap to get it to sit down - and it can be hard to do either or both of those if your engine is close to the firewall. But it can be done, and then you shouldn't have anything popping off.
 
And the answer is....

You know I really hate to write this post but full disclosure demands it.

The fix was simple; squeeze the terminal ends just enough to make them slightly out of round. They were slipping over the rings on the coil posts without making solid contact. Now they give the audible snap and are hard to pull off.

It seems obvious now.
 
THANKS

Thanks for posting your find Don. I have not yet had that problem on the aircraft, but I have at the plug end on the cars.

Another tip to add to the trouble shooting checklist.

Regards,
 
You must log in or register to reply here.
Back
Top