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stihl TS350 has clank in engine

Started by coastlogger, October 06, 2013, 10:08:56 PM

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coastlogger

Hey guys
Recently "aquired" 2 boxes of Stihl parts. Built up a TS 350 cutoff saw, which runs quite nice EXCEPT there is an impressive clatter in the engine somewhere. I noticed this right away after Id got the cylinder bolted on and was able to roll it over under compression. There is a clank at about the time piston rolls over TDC.No clank with spark plug removed. No evidence of piston hitting plug etc.Assumed bad con rod brg or wrist pin;dissassembled,seemed fine. ie no noticeable slack.The con rod will rock side to side maybe 1/16" plus on the crankshaft,but no up and down play.
Really seems to me the con rod must be the issue but sure doesnt seem like it "could" be given the above.Any thoughts?
The other con rod/crankshaft in the box had identical side rocking. Of course I dont know if both were good or bad when dissassembled.A crankshaft is $120 on ebay Im thinking I might have to invest.Anyone have a spec on con rod slack/tolerance?Or any other ideas what issue may be?
clgr

sablatnic

My first guess would be a worn piston skirt, which allows the piston to rock as it passes tdc. Have you run it yet, and if, does it rattle a lot?

coastlogger

It does rattle when running.Yes  that could be it. I used the best piston out of box, it had minor scuffing which I cleaned up in a few seconds with fine sandpaper. Still, I guess that would make it smaller. Im going to take it by a mechanic's shop todat and get him to listen to it.Talked to him on phone he suspected crankshaft bearings. I like piston better....Interestingly I recently bought a rototiller with Briggs Intek engine which makes exactly the same noise. Have tilled for two seasons now and it hasnt got any worse. Hoping when I get the cutoff saw sorted Ill have the tiller figured too.
clgr

AdkStihl

Crank or rod bearing......sorry for the bad news  :embarassed:
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coastlogger

Thats what 2 guys who listened briefly told me also. They also said theyd heard worse. Im going to run it on 25-1 gas and see if/when it gets worse. I got the thing to maybe cut a pipe or cable a couple of times a month so it could conceivably last quite awhile. Yes I am familiar with the connotation "dreamin".
clgr

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