Stihl MS181 ignition coil

[EricBradley]

The majority of the new stihl saws have the plastic insulator, some just have plastic washers, the part number is correct 1139 is the series of saw, this equates to the 171 181 211. 1302 is the ending of the part number, all that's missing is the 400 in the middle like all stihl coils have, so the part number is 1139 400 1302. Not sure of the configuration of the coil / flywheel but you need to get a coil that ends in the same last 4 digits as your origional or the part that has replaced it, some flywheels and coils you cant mix and match. If the holes wont line up with the mounting holes on the cylinder its deffinately the wrong coil.

[spandit]

Thanks. The holes line up but the body of the coil won't fit past the cooling fins on the cylinder head to actually bolt it down.

 

From reading on listings such as this:

 

STIHL MS171, MS181, MS211 Ignition Module / Coil [#11394001307] | eBay

 

the part ending 1307 will replace parts ending 1302. I suspect the part I bought is just a really crappy Chinese part that is badly made and the seller doesn't actually check that they fit. Think I'll go and buy a genuine part

[spandit]

MS180 coil part no. 1130 400 1302

 

MS181 coil part no. 1139 400 1307

 

 

I think the red number denotes the chainsaw model. The 1302/1307 denotes as to how new the part is (as in the 1307 has superseded the 1302)

[EricBradley]

http://www.cnczone.com/forums/attachments/1/2/8/1/3/506898.attach

[spandit]

I don't know what that link is supposed to be but doesn't work on my computer

[spandit]

Oddly, with a spark tester gadget plugged in ([ame=https://www.amazon.co.uk/Laser-2780-Ignition-Spark-Tester/dp/B003AN1VPW]Laser 2780 Ht Lead Ignition Spark Tester: Amazon.co.uk: Car & Motorbike[/ame]) with a metal bar in place of the spark plug it lights up well and with one particular car spark plug I get a smaller light but can't get any arcing across the plug electrodes. Don't know enough about coil packs to know how they'd degrade like this. Still struggling to find a replacement

[bmp01]

Probably arcing internally somewhere when it achieves the required voltage, insulation breakdown. ... But it could be generating a voltage upto the point where it arcs internally and maybe that's what the tester is telling you.

Of course if the voltage when insulation breaks down is not high enough to create an arc across the air gap of the plug then the plug never sparks. You could try closing the plug gap down to 10 thou, 0.25mm, it might arc.

Arcing could also be from the plug lead or plug cap, especially if damaged and dirty. Plug lead will be integral to the coil on these no doubt though.

 

bmp01

[spandit]

It's all potted with integral plug lead as you say so can't really diagnose where it might be internally arcing. I've ordered a genuine part now (albeit ending 1307) so hope that fits. If it doesn't then I've got some scrap metal for sale

[spandit]

Well. New part ordered. Box said 1307 but part says 1301. It fits but still not getting a spark.

 

I have an old strimmer engine with the same sort of thing and by spinning it with the drill I can get a decent spark from the strimmer spark plug (and quite a jolt, as it happens!) but can't get a spark from the Stihl spark plug (I've lowered the gap a bit too to the same).

 

Putting the strimmer spark plug into the Stihl coil produces no spark either. I've replaced the earth lead too to no avail. Gap between the armature and the flywheel was set with a feeler gauge to about as thin as I could get (tried with thicker settings too)

 

Any other ideas?

Edited May 30, 2017 by spandit

[EricBradley]

disconnect the two wires and try it, have you got the insulator in place?