What's happening to my bars???

[clattin]

Why is this happening to my guide bars? See the blue arrows on the pic. These are 2-20" bars and 1-16" bar off my Stihl MS290. The chain is getting stuck at this lower point on the bar and obviously getting very hot. After this happens once, the drive links get stuck there and then the bar is shot. The saw seems to be oiling properly. What else could cause this? I'm VERY tired of buying new bars!

 

[Andyshine77]

I can't see any detail in the pictures. However my guess is your chains are too loose. This causes the chain to come off the tip do to centrifugal force, the thain then bangs back into the bar causing the rails to mushroom, which could make the rail grove too tight. Um also going to guess you may be also running excessively dull chains. The only other thing I could think of, is your pinching a bar in that area, which is unlikely. You should also be flipping your bars regularly.[emoji111]

 

[TLG]

Just a suggestion. Look at you connecting driver links on your chains. The radius side of the link should face downward. It helps the chain roll over the nose of the bar and drive sprocket of the clutch. I've seen some on upside down with the flat side down instead of the radius side. Normally when this happens the chain hangs on the clutch as the sprocket is a smaller diameter. But your clutch sprocket may be worn and wouldn't bind. BTW these chains were put together by a reputable shop too. Was a bugger to find. Tim

Sent from my XT1635-01 using Tapatalk

 

[HarleyT]

Show us a pic of the drive sprocket [teeth], and the bottom links of the chain.

 

[KarlD]

...and confirm that you are using ‘proper’ bar oil and not old skanky motor oil. I spent ages trying to help someone with an oiling problem without asking this question, only to find out that he was recycling his deep fryer oil

 

[clattin]

I'll take some more pics and post them in a couple of days. I'm out of town until Thursday. Thanks so much for all the input! Is it safe to assume that those bars are shot? Probably can't say until you see pics though

 

[clattin]

...and confirm that you are using ‘proper’ bar oil and not old skanky motor oil. I spent ages trying to help someone with an oiling problem without asking this question, only to find out that he was recycling his deep fryer oil

Yeah, I use real bar oil........but thanks for checking!

 

[U&A]

I can't see any detail in the pictures. However my guess is your chains are too loose. This causes the chain to come off the tip do to centrifugal force, the thain then bangs back into the bar causing the rails to mushroom, which could make the rail grove too tight. Um also going to guess you may be also running excessively dull chains. The only other thing I could think of, is your pinching a bar in that area, which is unlikely. You should also be flipping your bars regularly.[emoji111]

I think Andy nailed it


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[huskihl]

Every time I’ve seen hot spots like that it’s from pinched rails. Usually it’s noticeable by eye. Take your scrench and pry it back open. The bars will be fine

 

[Mike Kunte]

My money is also on a loose chain. Seems that the bars are flipped occasionally, because the bar has the same marks at the "top"... Hope you find the cause - let us know when you do. That way we all get to learn!

 

[Franny K]

That is pretty much normal in the reality I live in. Not the part about pinching the drive links though. If you do not like it use hard nose bars. My logic is that the chain is going in a circular motion around the nose sprocket and then re directs down the length of the bar. It crashes into the bar and makes what the blue arrow points to. Similar happens where the chain comes off the drive sprocket and slams into the top of the bar's tail. The above suggestions will help minimize but it just goes with the territory so to speak the way I see it. Cutting with the top of the bar would keep tension on the chain in that area and minimize the preening as opposed to cutting with the normal bottom of the bar, seems to me anyway.

 

[CR888]

...and confirm that you are using ‘proper’ bar oil and not old skanky motor oil. I spent ages trying to help someone with an oiling problem without asking this question, only to find out that he was recycling his deep fryer oil

And what did you end up diagnosing? Your clever diagnosis concluded that fryer oil was causing problems?

 

[KarlD]

And what did you end up diagnosing? Your clever diagnosis concluded that fryer oil was causing problems?

I concluded that he was a muppet and I immediately lost interest in helping him. I’m not going to waste my time researching the oiling properties of used fryer oil

 

[Gypo Logger]

Other than shot cutters,sprocket and drivers, all I can think of is excessive cutting using the tip of the bar. AKA: ram rodding.