Another bad MS361 Ignition Module?

[bwalker]

Would using a type of sparkplug that does not match coil cause the death of a coil over time?

No. If your gap got way out of wack to the wide side it might shorten coil life, but that would take a long time to manifest itself.

 

[bwalker]

Keeping the saw clean is very important. Caked on sawdust mixed with oil insulates the heat in like a blanket. Storage of the saws in a environment that keeps them below 140f is also important. I have experienced failed coils on saws stored in a attic through a summer.

Yes and on that particular a muffler mod is a must have. It has the most choked up muffler in the business.

 

[Old2stroke]

If you are insulated from ground you will feel nothing.Ever wonder how a tiny bird can sit on a 150000 volt hydro wire and fly away and do it time after time.
I am in full agreement with you that the saw will build up the voltage potential higher than normal but nothing happens unless there is a source to ground.
Kash

If you are insulated from ground, the voltage is just not high enough to break down the insulation and cause any current to flow so you don't feel anything. That's what keeps the birds safe. The voltage is still there, just no discharge current is produced, so you are right that nothing happens unless the energy can find a path to ground. A coil is just a transformer and any time current is driven through the primary, the secondary voltage will appear at the output whether there is anywhere for it to go or not, and the point I am trying to make is, if a plug lead is disconnected and there is no normal discharge path to ground through a spark plug that would limit the voltage to about 10kv to 20kv, the voltage can rise to as high as 60kv or higher depending on the ignition system and this level of voltage can be high enough to break down the fragile enamel insulation of the secondary wires and find a path to ground through the coil windings, eventually leading to coil failure. Some more expensive ignition systems will have voltage limiting spark gaps built into the secondary but you won't find them on chainsaws.

 

[stihltech]

I always use a ground wire from tester to metal. I also use a spark tester. Very simple, open up the gap very wide on a plug. My tester is a non extended tip plug with the side electrode removed. You can buy them or make one. It will show if a spark is weak right away.

 

[arto_wa]

If you are insulated from ground you will feel nothing.Ever wonder how a tiny bird can sit on a 150000 volt hydro wire and fly away and do it time after time.
I am in full agreement with you that the saw will build up the voltage potential higher than normal but nothing happens unless there is a source to ground.
Kash

Hi Kash,
No big deal, but '150000 volt hydro wire' is Canadian speak - many in the rest of the world have no idea what you mean

Cheers

 

[KASH]

High voltage electrical transmission power line.
Kash

 

[Lightning Performance]

One thing not mentioned is a bad plug wire or spark plug that might seem to run pretty good.

On engines with more than one cylinder and running a bad spark plug or plug wire can fire internally and burn out internal wiring as well as the chip set or a capacitor. This is often seen as cross-fire in the common distributor cap. A coil doing this can overheat itself internally and break down wiring on the windings and the electronics.

Much more than meets the eye going on inside a single cylinder magneto ignition source. This applies equally to CDI systems and points setups. The voltage will drop to the nearest ground point. If it doesn't then bad frequencies build up and cause issues in multiple locations. The primary has power and it must go somewhere or it just builds up heat until failure. This isn't a test or to be debated it's just a fact of the life cycle in any coil of any type. Bad spark plug ran with miss-fire can cause the same issues over time.

Enjoy your learning experience.

 

[Cedar Row]

Thanks, Pioneerguy600,
As usual your comments are very helpful. I think the trick for keeping a coil working is to make sure to let the saw idle after cutting, especially after heavy cutting. I was also curious about the gap, you answered that issue well also.
Thanks again,
Cedar Row

Installed a new after market (inexpensive) coil and got a spark, this after retrying four old coils. No spark from the old coils. Each time that the saw wouldn't start in the past a new coil fixed the problem, but eventually they stopped working. Got the spark with the Stihl spark tester, and the saw kicked over. Haven't reassembled saw yet, I have a 261 and have been cutting firewood with it, making sure to let it idle before turning it off. Haven't read about any problems with the 261 coils, but I'm being careful.

 

[Northerner]

i have also replaced a coil on a 361 for a customer, pricy unit, wow! $157.00, that was a year ago