Stihl ms-231 chain tensioner part: bad design or accident?

[Medit]

Hi there,

A friend of mine bought recently a brand new STIHL MS-231 and after a few hours of work, the chain tensioner slide broke.

In this PDF parts diagram it is labelled as "3" with part number  "1123 640 1900":

https://www.diyspareparts.com/parts/stihl/diagrams/ms231-c/bf694571-ad64-45d2-b717/

It is basically a metal plate (3mm width) which on one side it has a round conical hole of diameter ~7mm

Onto that hole a cylindrical nail is fitted (not soldered). And that nail just popped out.

To begin with, that design seems flawed to me (non-technical, no mechanics background). it was not soldered. it was just pushed in the conical housing. The nail seem to have a security ring as if to secure it into the hole. But then how did it poped out?

I am writing this because I want to find out if this is a recurring problem often encountered by you hardened log-choppers on this particular chainsaw model.

If it is rare or unseen problem, then my friend must have been doing something wrong. WHAT?? Could it be that the chain overheated so much that the plate expanded and the nail came out from its housing? I saw it overheating and then he put some more oil in. But this requires extreme overheating no?

If this is not a rare problems and others have encountered it, then what?

bw,

a friend from the Mediterranean Sea.

 

[Khriss]

Take it back to the dealer, that sounds rubbish  ? K

[Wonky]

My question is, did you over tighten the chain.  Do you have any pic's of the parts that broke. ?

[Moose McAlpine]

7 minutes ago, Wonky said:

My question is, did you over tighten the chain.  Do you have any pic's of the parts that broke. ?

 

Would definitely explain overhesting the bar too if it was overtightened. I replaced an MS201T chain tensioner today for chewed up threads from being overtightened, pin wasn't damaged.

[Stubby]

7 hours ago, Medit said:

Hi there,

A friend of mine bought recently a brand new STIHL MS-231 and after a few hours of work, the chain tensioner slide broke.

In this PDF parts diagram it is labelled as "3" with part number  "1123 640 1900":

https://www.diyspareparts.com/parts/stihl/diagrams/ms231-c/bf694571-ad64-45d2-b717/

It is basically a metal plate (3mm width) which on one side it has a round conical hole of diameter ~7mm

Onto that hole a cylindrical nail is fitted (not soldered). And that nail just popped out.

To begin with, that design seems flawed to me (non-technical, no mechanics background). it was not soldered. it was just pushed in the conical housing. The nail seem to have a security ring as if to secure it into the hole. But then how did it poped out?

I am writing this because I want to find out if this is a recurring problem often encountered by you hardened log-choppers on this particular chainsaw model.

If it is rare or unseen problem, then my friend must have been doing something wrong. WHAT?? Could it be that the chain overheated so much that the plate expanded and the nail came out from its housing? I saw it overheating and then he put some more oil in. But this requires extreme overheating no?

If this is not a rare problems and others have encountered it, then what?

bw,

a friend from the Mediterranean Sea.

 

Did the chain oil tank run out ?

[Medit]

20 minutes ago, Wonky said:

My question is, did you over tighten the chain.  Do you have any pic's of the parts that broke. ?

The owner is experienced and Iam sure he did not overheat. and put oil regularly. the only thing iam not sure is over-tightening. The pin was lost. the plate (slide) looks brand new and not a scratch on it.

[Medit]

37 minutes ago, Khriss said:

Take it back to the dealer, that sounds rubbish  ? K

And that he did with 2 weeks of delays just to get a new part and not change the chainsaw. Anyway, it cuts fine now, I was just wondering whether he did something wrong or the design of the slide+pin is flawed. Obviously if you lot have not encountered this problem regularly then it's either the usage by the owner or that particular part was faulty. Thanks for responding,

best wishes

[Stubby]

41 minutes ago, Khriss said:

Take it back to the dealer, that sounds rubbish  ? K

It is a Stihl after all Khriss . ☺️

[bmp01]

L & S Engineers says this part is used on the following saws:

 

Description

Tensioner Slide for Stihl HT73, MS230 Chainsaw
Genuine Stihl Part
OEM No. 1123 640 1900

Suitable for the Following Applications:
MS180 / MS180C, MS210 / MS210C, MS230 / MS230C, MS250 / MS250C, MS171 / MS171C, MS181 / MS181C, MS211 / MS211C, 019T, 021 / 023 / 025, MS231 / MS231C / MS251 / MS251C, MS241C, E140, E160, E180, MSE140 / MSE160 / MSE180 / MSE200, MSE141 C, MSE170, MSE190, MSE210, MSE230, MSA160T, HT56 C, HT70 / HT70K / HT75, HT73, HT101, HT130, HT131, HTE60, HTA65, MS190T, MS191T, HT-KMTo

 

Widely used, ---> design is ok. Either a one off bad part or user error. Single bar nut on 231 by the looks of it, wonder if it was left nipped up but not tight. If you had the broken parts to hand it might be obvious if not we'll never know.

 

 

 

Edited November 26, 2020 by bmp01
Typo

[Wonky]

Pictures answer a thousand questions..

 

I think, but could be wrong.. it was over tightened and chain cover not tightened and the chain shrunk when cooled then broke the thing..

 

ive seen bent crankshafts and bent bars from having the chain to tight. So that’s why I think operator error. I could be wrong but all that pin is ment to do is tension the chain then the clutch cover takes over when the nuts are tightened and holds the bar and chain.