Sometimes the best tools are the ones with a simple design that works.
Text, photos and video by Tom Hintz
Posted – 12-15-2016
One of the realities of virtually any type of internal combustion engine is that it can occasionally refuse to start. I have about 40 years of experience with street and racing engines and know that when one won’t start we look for two things – is it getting fuel and is there spark. That same sequence of investigation applies to our model engines as well. But when we check for spark we run into a problem that is common on both model and automotive engines.
To check for spark we pull a spark plug or find a spare, push it into a plug wire and then hold it against the engine block while turning the engine over to generate spark. A big mistake I see people make with model engines is that they do not push the plug all the way into the plug wire terminal cap to be sure it is easier to get back out. If the plug is not fully seated in the terminal the plug will not spark no matter how good the ignition is because the circuit is not complete. The metal tip at the top of the plug has to be fully in contact with the clip in the top of the wire terminal for the circuit to be completed.
Once you fully seat the spark plug and run the test we need to get the spark plug back out of the ignition wire terminal and this is where the problem comes in. There is nothing large enough to grab with your fingers to pull the plug back out. The obvious answer for many is to grab a pliers and jerk the plug out of the terminal by the threads as they are about all that is showing. But, if you damage the threads at all, usually bending or flattening the edges of the threads themselves over a bit, every time you screw that plug into the engine it is gouging the internal threads just a little bit, but consistently making them deeper and reducing the holding surfaces. Before long you can strip the threads in the engine quite easily. I have seen threads get weak enough that the plug can blow out of the hole when the engine is running.
The Purple Plug Puller is made in the USA from 6061-T651 aluminum bar and given a tough anodized finish after machining is complete. The folks that make the Purple Plug Puller told me that,” There really is nothing special about the knurling”. Perhaps nothing special to how they do the knurling but I have seen lots of higher priced tools with far less defined knurling which translates to lesser grip.
We used to kill more spark plugs just
getting them out of the plug wires.
The Purple Plug Puller is 100mm long and 25mm in diameter. That is a nice feeling handful when in use. The ends have 1/4-32 and M10 threads. The M10 thread is for the nearly universal CM6 spark plug used in RC gasoline engines today. In the center of the Purple Plug Puller are two more threads, M12 and M14. The M14 threaded hole accepts the older (large) plugs used by engines like the older Brisons and Zenoahs. The M12 thread was put there because they had space but it currently has no design use for specific engines. The makers of the Purple Plug Puller say that if they can identify another needed thread the M12 will be replaced with that.
This is going to be the shortest field test I have ever done and that is mainly because the Purple Plug Puller is a simple but well thought out design with a specific need, no special instructions and no skills to be developed to use it. Screw the Purple Plug Puller over the threads of the spark plug, get a firm grip on the wire terminal with one hand, the Purple Plug Puller with the other and pull the plug out of the wire terminal. That’s it.
The Purple Plug Puller does what the makers say it will and it does it easily. The most surprising thing about the Purple Plug Puller is that despite being manufactured in the USA, it costs just $15.00 (12-15-2016) and you get it directly from the manufacturer at the link at the end of this review.
If you still don’t see a good reason to own a Purple Plug Puller I can’t help you. To me the Purple Plug Puller is a simple no-brainer that makes a lousy task easier and I am not jerking the ignition box loose in the plane when the wire finally comes off of the plug unexpectedly. Get one or you can never whine again about dinging up your plane or hand when trying to get the plug out of the wire terminal.
Visit the Purple Plug Puller manufacturers web page – Click Here
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