blew out spark plug today

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duramaxman05

Minister of Fire
Aug 17, 2014
739
Perryville, Mo
I was sawing today and all of a sudden, a loud poof and the saw quit. I pulled the rope a no compression. So i took the air filter cover off and found it blew the spark plug out. This is on my stihl 441. How does everyone fix this? I have never had this happen. I do wanna fix it right because i have no plans to get rid of it.
 
I've never done it with a saw but on small engines many use a heli coil kit. Not sure if that would work here with all that plastic
 
I have never used a heli coil either. I know some mechanic huh. I guess i will check into that
 
Seems to be a defect with the 441. I've used several that had the same issue. Depending on age of the saw I would try to get the dealer to help out.
 
I've used a solid insert kit similar to (broken link removed to http://www.ebay.com/itm/SAV-A-THREAD-SPARK-PLUG-THREAD-REPAIR-KIT-14MM-1-25-HELICOIL-TAP-M14-/291657629746?cmd=ViewItem&hash=item43e8264032:g:MqkAAMXQWzNSpRHq). It was fairly straightforward, but doing it right requires pulling the cylinder because otherwise there's a big risk of dropping metal bits into the combustion chamber where they'll do damage. The finished job looked really clean and solid. I sold the saw not long after (disclosing the repair, of course) so I can't speak to its longevity.
 
If you're mechanically handy, one option is to find a replacement cylinder and swap it in. You might be able to find a good used OEM one and I believe several aftermarket companies are offering MS441 kits now.
 
Are all the threads stripped or did it just vibrate loose and then popped out? If it vibrated loose you might just be able to clean up the threads with a tap and just put a new plug in. Otherwise I would pull the cylinder and have it welded then drilled and re-tapped.
 
Those of you saying "just pull the cylinder, and then ...", I hope you understand that on a 441 that is a bizarrely complicated undertaking. If you can get your hands on an IPL for that saw, take a look at it. No logical reason for that sort of Goldbergian complexity.

IME, there are probs with some A/M cylinders. With at least one, from Hyway, there was interference that had to be removed- a wee bit of grinding on the casting.

+Still haven't heard about the condition of the plug-bore threads..
 
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I am going to check it out today. Hopefully it just came loose. I didnt look real close at it yesterday. I put a new plug in it earlier last year so maybe it just came loose.
 
Just put an insert (Helicoil or one of the others) and run with it. The threads of the insert are stronger than the Aluminum they are going into.
 
I tore into the saw today. The threads looked descent. So i put a little grease on the spark plug threads and screwed it in. It went in good and tightened up fine. I guess it just came loose and worked itself out. I will run it and see what happens. Thanks everyone for the info.
 
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