Chain tensioner slips, hoping for diagnosis

[elitts]

Let me preface this by saying, this is my first big boy chainsaw. I made do for my previously (more limited) needs with an el-cheapo electric one of the sort where you just buy a new one if it breaks.

I picked up a used 440 Magnum. Seems to run fine, except that the tensioner isn't working correctly. I can turn the screw forever and it never moves forward. If I apply sideways pressure on the nub while turning the screw, it will slide forward, but not smoothly, it sort of jumps and skips. And then once the tensioner is at maximum extension, if I push it backwards with a finger, it takes very little pressure and it will slide all the way loose.

I'm going to assume something is either broken or disconnected. I'm also going to assume this part is commonly subject to breakage.

Question 1: Would anyone like to speculate from my lay-person description of the problem as to what part may be broken?

Question 2: Assuming you think you know what part needs replacing, is this a DIY job or am I likely to break other stuff and I should bring it to a shop?

Thanks in advance.

 

[rich450es]

It sounds just like the Adjusters on the farm Tech Chinese clone saws. Just wondering next to the muffler Outlet are there numbers stamped on the case?

 

[FWANK WIZZO]

Something is stripped, the bolt or the “nub”. Theres only a couple parts, pull it out and see whats up. Dont be scared, its not the space shuttle.

 

[homemade]

Something is stripped, the bolt or the “nub”. Theres only a couple parts, pull it out and see whats up. Dont be scared, its not the space shuttle.

What he said.

 

[Efisher26]

Yup, stripped, screw or nub


Sent from my iPhone using Tapatalk

 

[HarleyT]

Sounds painful!!!!

 

[HarleyT]

here...

 

[user 122190]

I had a neighbor replace his. He was having a similar problem. Had the nub(?) installed backwards/upsidedown. I could see the nub wasn't going into the bars hole. Easy fix.

 

[elitts]

Ok, pulled the metal plate off today, the threaded hole that moves along the screw had broken off inside the housing. Seems simple enough, and it's not even expensive.

I also saw that the chain catcher was mangled beyond all repair, so I guess I'm replacing that too.

Thanks for the help!

 

[Wood Doctor]

Stihl did a very good job of designing a chain tensioner mechanism that is twice as complicated at it needs to be and with twice as many parts. Then they used the same design on dozens of models and thousands of saws. We have all been victimized by it at one time or another.

 

[HarleyT]

Yeah, but since it isn't much of a problem,
well........

 

[Frank Rizzo]

Let me preface this by saying, this is my first big boy chainsaw. I made do for my previously (more limited) needs with an el-cheapo electric one of the sort where you just buy a new one if it breaks.

I picked up a used 440 Magnum. Seems to run fine, except that the tensioner isn't working correctly. I can turn the screw forever and it never moves forward. If I apply sideways pressure on the nub while turning the screw, it will slide forward, but not smoothly, it sort of jumps and skips. And then once the tensioner is at maximum extension, if I push it backwards with a finger, it takes very little pressure and it will slide all the way loose.

I'm going to assume something is either broken or disconnected. I'm also going to assume this part is commonly subject to breakage.

Question 1: Would anyone like to speculate from my lay-person description of the problem as to what part may be broken?

Question 2: Assuming you think you know what part needs replacing, is this a DIY job or am I likely to break other stuff and I should bring it to a shop?

Thanks in advance.

Stripped and or broken screw / nub ... easy fix just take your time ... that saw will serve you well once ya whip it into shape !

 

[elitts]

Ended up replacing the worm gear/shaft assembly too. While it wasn't visible to the naked eye (at least not mine) when I got the new nub in there the whole assembly kept wanting to hop up once per rotation on the screw. Now it works very well.

Random bonus question. Is it normal for a saw to leak bar oil if it's left sitting on its side for a time?

 

[oldfortyfive]

...Random bonus question. Is it normal for a saw to leak bar oil if it's left sitting on its side for a time?

Every saw I've had did

 

[elitts]

Every saw I've had did

Ok, good, TY. I thought it must be normal since the bar oil is essentially in an open reservoir so it dribbles on the chain, but confirmation is good.

 

[oldfortyfive]

I always drain the oil when done.

 

[ironman_gq]

Mine don't leak bar oil, when they do it's almost always the oil tank vent. Cheap and relatively easy to replace.

 

[CentaurG2]

I would have left it broken. I find it faster to adjust the chain without the tensioner. All saws will leak bar oil if left for a long enough period of time. If you don’t drain them, store them on several layers of carboard. Use the now oil soaked carboard as quick and easy fire starter.

 

[rd35]

Even if your tank/oiler does not leak, the bar groove generally has a good bit of oil in it just after you finish using the saw. That oil usually runs back to the saw via gravity and drips till gone. Not very much, but a few drips usually.

 

[elitts]

I would have left it broken. I find it faster to adjust the chain without the tensioner. All saws will leak bar oil if left for a long enough period of time. If you don’t drain them, store them on several layers of carboard. Use the now oil soaked carboard as quick and easy fire starter.

How would I tighten the chain when the nub slides backwards freely, allowing the bar to slide back and putting slack in the chain?