McCulloch B43 BT Strimmer: Spark plug change

danboy775

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May 28, 2020
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Hi,

I'm new to the forum and came here looking for help replacing the spark plug on my McCulloch strimmer.

I have zero experience tinkering with engines so could really do with some idiot proof help please.

My strimmer rolled off a stand and landed on the garage floor smashing the spark plug. So I ordered a replacement. The spark plug which was originally in the machine was a Champion RCJ6Y so I looked on Amazon and found one that said it was equivalent to this plug.
I tried putting the plug in, it fit in the top of the engine okay but then I noticed that it has a threaded connection on top, however the male thread in the spark plug cap was too wide to fit the female connection on the top of the spark plug and would not screw in.
So I done some more research online and ordered another spark plug, this time an NGK BPMR7A which arrived today. I checked that it fitted the thread connection inside the spark plug cap which it did, it also fit in the top of the engine....however...how on earth do you fit this thing??
You have to screw it one way onto the thread on the spark plug cap then the opposite way when fitting it to the engine so it unwinds from the cap!
I watched a couple youtube videos prior to starting, and all the videos show the person just pushing the cap on to the top of the spark plug however I cant do that with this strimmer.
I've attached a couple of photos showing the old spark plug in the strimmer and also the inside of the spark plug cap showing the threaded connection.

Any help or advice would be most appreciated.
 

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dougand3

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The boot/cap just pushes straight on. Is the broken central lead still in the "spring"? Can't tell from the pic.
Or on some machines, you unscrew the "fat" adapter off the plug and insert the threaded screw straight into the boot spring.
 

danboy775

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Joined
May 28, 2020
Threads
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The boot/cap just pushes straight on. Is the broken central lead still in the "spring"? Can't tell from the pic.
Or on some machines, you unscrew the "fat" adapter off the plug and insert the threaded screw straight into the boot spring.
I did wonder if part of the old plug may still be stuck in the cap, so I gave that threaded connector a good tug and the top of the old spark plug popped out. Got the new plug fitted and the strimmer started fine.
Thanks for your help.
 
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