ScotiaMcBlurty

She lives 2 oil baths, good load of WD40, 2 upside down overnight hangings to drain it all out, filled the fuel tank .... and broom broom! Burning a bit of oil now obviously, but that'll clear up in a min or two. Happy days - many thanks to all for their help. If someone who is barely mechanically competent can get it going, then you guys must be good. Cheers!

Openspaceman ... above and beyond the call of duty May just take you up on that ... will get the pulley off this weekend if I can and give it another oil bath. Just need to get the kids through GCSE and A levels first - chaos right now in the house (sigh). Will message you directly if that's ok. 👏 (and yes, appreciate what you say about new saw vs cost to fix ... used to know the guy who owed the dealership, but under new ownership now, so yes, I'd also expect to pay for diagnosis if it was not an obvious problem ...) Thanks guys and gals.

Gave it an oil bath last night ... then left it to drain out overnight. Cord does seem a little better (or maybe its wishful thinking!), but not free enough to start. So will have a look at the pulley tonight as well - at least remove that variable from the equation. If nothing else, I'll learn more about how it works ... but I fear a trip to Honey Brothers (dealer) might yet be on the cards. Cheers all.

Filler caps are both black, screw down. Plug hole is 10mm diameter. My engine output is also slightly different to the manual you posted (I only have 1.6HP). Can only assume for some limited time period they used this plug in the MS 170, right?

Hmmm ... thanks Pleasant, plot thickens. My manual says "STIHL MS 170" on the cover. Its only for the MS 170, no other guidance for any other model is provided (each page says MS 170). Its 44 pages long, and page 44 is blank. Copyright statement is "ANDREAS STIHL AG & Co KG, 2013". Picture of the Engine Spec page is attached... strange one this.

Thanks Pleasant. Re plug. The online Stihl manual does say "NGK BPMR 7 A" but my hardcopy manual, which I still miraculously have, is defo "NGK CMR6H". So I assume the design changed at some point. Top of piston looks good from what I could see through the exhaust port.

Right, the plug I have is a NGK CMR6H. Have dug out the manual and its the right one. Book says Spark Plug (Supressed) : Bosch USR4AC, NGK CMR6H. Which does make sense, as even if I just cover the hole with my finger, the cord still goes tight. Will try the WD-40 wash out tonight.

Will check the plug serial # at lunch. Its been in there since the last service ... but that's doesn't mean to say its not right!

Thanks guys. -No fuel coming out of exhaust port when I tug the cord with the plug out, so assumed not a hydro lock (?). -Did see one of Spud's posts - hence I turned it upside down last night, even after a couple of hours, not much had dripped out of the plug port -Even with the plug only screwed in a rotation or two I get the tight cord, so plug probably not too long Have attached a couple of low res photos ... plug was a bit manky when I took it out (on the outside) - and perhaps leaking.... (That photo was taken before I turned the saw upside down). Muzzle filthy. Its been good as gold until this issue. Dealer serviced it a couple of years back, but suspect they just change the filters and not much else. Will try the WD40 as you say Chris .. can't harm. Let you know how that goes - appreciate the help guys.

Hi guys - sure you have all seen this one before, but nothing out there totally matches my symptoms, so here goes.... - Stihl ms-170, 7 years old, been good as gold for years - Not used for 3 months - Starter cord stuck - Take plug out, cord turns easily. So my thinking is to look for an exhaust blockage. - Muffler is indeed dirty black, but can't see any blockage. Taken it off, piston looks clean / sliver, rings visible, no blockage, moves freely. Interestingly, there is no gasket between cylinder and muffler, just a metal plate which kind of surprised me. (???) - Put plug back in, kept muffler off ... still cant pull cord ... so it's not a muffler blockage What options are left ... blockage from the carb? Any thoughts appreciated - hate to give in and take it to a dealer - probably cost me more than the saw is worth Not an expert on this, but happy to get stuck in. Cheers!