Stihl MS361 running issues

[Nick Harrison]

Evening all

 

anyone ever had or know of persistent problems with tick over on the MS361? have had the saw for about 7/8 years now and it has always had the same problem...it will run fine for the first 20 mins or so and then turn into a proper pig, fine whilst on the trigger but as soon as you put it down with chainbreak on or off it cuts out and can then be a bugger to restart!!

 

have had it looked at by a couple of reputable mechanics but the problem has persisted. it's difficult for a work shop to replicate the fault as it only happens after near constant use of about 20 mins...weather temp seems to make no difference either.

 

bumped into a stihl rep shortly after buying the saw and he accused me of using the wrong mix, i explained that all my other saws all worked fine but he was having none of it....what you'd expect from a sales rep i guess!

 

any clues or advice please??

[inthewoods]

Without stating the obvious... Have you cleaned the spark arrestor & air filter. Changed / gapped the spark plug. Also checked fuel line & filter.??? What's the compression at cold & after 20 minutes work? May just need a rebuild :-o

[Nick Harrison]

Without stating the obvious... Have you cleaned the spark arrestor & air filter. Changed / gapped the spark plug. Also checked fuel line & filter.??? What's the compression at cold & after 20 minutes work? May just need a rebuild :-o

 

have tried all the above except fuel line and filter...my logic says if there was fault with either of these it would be evident as soon as you start using the saw??

 

haven't thought about checking compression at different stages, whats your thinking behind that?

 

bear in mind also that this fault has been there from new..took it back to the supplier at the very beginning and they maintained there could find no fault, as mentioned before, is difficult to diagnose a fault when it doesn't appear until at least after 20 mins of near constant use...eventually gave up arguing with them and have just put up with the problem ever since.

 

worth noting that in a previous role working for a LA we had exactly the same issue with their 361...problem was never sorted during my time there....but perhaps more than just a coincidence.

[Mark_Skyland]

Could be the coil breaking down when warm, check the gap between that and the flywheel, should be about .25mm.

 

Your saw sounds exactly like one with low compressionoso worth a check at cold and hot, even though it's been like that from the beginning.

 

If you are using stihl red two stroke it could be worth an upgrade to hp super, a lot of customers notice the difference in how well their saw runs when using a better oil.

[Nick Harrison]

Could be the coil breaking down when warm, check the gap between that and the flywheel, should be about .25mm.

 

Your saw sounds exactly like one with low compressionoso worth a check at cold and hot, even though it's been like that from the beginning.

 

If you are using stihl red two stroke it could be worth an upgrade to hp super, a lot of customers notice the difference in how well their saw runs when using a better oil.

 

will check the gap on the fly wheel.

 

have a compression gauge instrument that i used a few years back whilst restoring a classic car, will see if it has the same size fitting as a chainsaw spark plug and if so take a look a the comparable compression readings.

 

thanks for advice, fingers crossed!

[inthewoods]

From new!? Yikes, well I run two Ms361s 1 from new 8yrs ago & the other 2nd hand last year & never had this kind of problem with 'em (both been faultless)

Have had a similar problem with ground maintenance kit when hot & the causes were - degraded fuel line & fuel primer (OK not on 361) a faulty / knackered gasket (head & carb on separate occasions)

For whatever reason heat build up is causing the problem, so expansion maybe altering fuel /air ratio or lack of compression.

[inthewoods]

Ps when you start her hot & blast the trigger full bore, does it fly or bog down?

[Stubby]

Partially blocked tank vent so trying to pull a vacuum ?

[inthewoods]

Partially blocked tank vent so trying to pull a vacuum ?

 

Fair point, or is it leaking?

http://www.lsengineers.co.uk/tank-vent-stihl-part-no-1121-350-5802.html

[Tree Tastic Care]

Had running problems with my 171 today . Started and wouldnt run , after 20mins I gave up went to get my 028 saw to do the job . Got back to yard 2nite , started the 171 and ran fine ?!!!