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355t unsteady idle

Nutball

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Apr 4, 2015
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Does anyone here have much experience running a 355t? I know not every saw has a perfectly smooth idle, but a 355t I have seems too unsteady to be normal. Generally it is most significant when warm. Sometimes it idles fast, often times the idle drops a lot when tipped clutch side down or forward a little, but not always. Also it isn't too difficult to get it hot enough (2-3 cuts) even in cold weather to fast idle with the chain spinning for a good 2 seconds after a cut. Maybe it is normal for this model to heat up quick, and to idle erratically. I think the 026 has been known to die whenever tipped forward. It's just a pain when the saw wants to die whenever you reach out to make a cut, but you can tip it every which way for a few minutes without it dying.
 

Marc-Antoine

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It looks like an air leak at the crankshaft's seal ( clutch side usually). If it's that, soon enough that will become worse, until you can't run the saw anymore.
I got this behavior with two ms200T and my ms440.
 

BeerGeek

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Sep 13, 2018
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Warren, NJ
I interchange my CS-355T w/my MS-193T for climbing, and I do not have any fast idling problems with it, no matter how I orient it up in the air
 

Nutball

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  • Thread Starter Thread Starter
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The main issue is the idle drops really low very quickly in certain positions, but not all the time.

I found a hole in the gas line, but I'm not sure if it was in a spot where it could cause a problem.

I've never put much trust into Echo crank seals ever since I saw a new engine appear to leak case compression, or suction (I can't remember which) from where the seals contact the shaft. That one ran well. I don't have a pressure/vac tester, but with what I can rig up it seems to hold pressure well enough but not vacuum. I'll check the seals, but it's relatively new.
 

Magnus

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Sound as it starv for fuel. It could be seals, It could be airleak in intake or fuelline too. It could be set too lean or not pump fuel as it should.
I would start with filter and fuel line. Then see if there is crap in tank, carb. Perhaps raise inlet needle lever a tiny bit (should be as high as possible without leaking).
If thats Ok I look in carb boot, see to it that its tight and good. If I still don't find issue I would test the seals or just replace them.
 
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