MS391 oil leak

[topchippyles]

3 minutes ago, Stubby said:

MS 391 is a semi pro / farm saw anyway . There was a spate of them having oil tanks crack I seem to remember .

You quote me and i will quote you ?

 

STIHL Recalls Chain Saws Due to Risk of Injury

• MS 391 Chain Saws.
• Hazard: The flywheel on the chain saw can crack causing parts of the flywheel to separate and strike users or bystanders, posing a risk of injury.

[Stubby]

Just now, topchippyles said:

You quote me and i will quote you ?

 

STIHL Recalls Chain Saws Due to Risk of Injury

• MS 391 Chain Saws.
• Hazard: The flywheel on the chain saw can crack causing parts of the flywheel to separate and strike users or bystanders, posing a risk of injury.

Yea . I would not want one .

[topchippyles]

3 minutes ago, Stubby said:

Yea . I would not want one .

Not even in a christmas cracker ?

Edited July 27, 2020 by topchippyles

[Stubby]

9 minutes ago, topchippyles said:

Not even in a christmas cracker ?

No ta .

[Estatesman]

Thank for that guys. I don’t have a problem stripping it down just needed a couple of pointers as to what to look for when I am doing it.

Thanks Frammo will look at that and rig something up for the air.

The saw does fine milling for my needs on my Logosol F1, just for projects of my own . Don’t cut big slabs .

[topchippyles]

12 minutes ago, Estatesman said:

Thank for that guys. I don’t have a problem stripping it down just needed a couple of pointers as to what to look for when I am doing it.

Thanks Frammo will look at that and rig something up for the air.

The saw does fine milling for my needs on my Logosol F1, just for projects of my own . Don’t cut big slabs .

Plenty big enough to mill with.

[spudulike]

You need to strip the clutch drum and clutch off, look at the area under the clutch and see if there are any obvious signs of cracks or wear. These 391/390 etc have a strange arm that pushes in to the oil tank union and connects up to the oil pump. It is possible the seals on the arm or the arm are damaged. The crank seals will NOT be an issue, there is no chain oil behind them!

Frammos idea of pumping the tank up a bit is a good idea, easier on the saws with rubber pickup pipes but possible by pushing a bit of big fuel pipe on to this arm union connector (you will recognize it when you see it)!

Sometimes you can fill up the oil tank with Petrol/diesel and if the leak is bad, it will come out a lot faster making it much easier to see.

Not much else to recommend, I wasn't being funny in my earlier post, sometimes it comes down to strip and diagnose. Damage through a mechanical failure rather than wear are difficult to diagnose unless it is a common failure!

[Estatesman]

1 hour ago, spudulike said:

You need to strip the clutch drum and clutch off, look at the area under the clutch and see if there are any obvious signs of cracks or wear. These 391/390 etc have a strange arm that pushes in to the oil tank union and connects up to the oil pump. It is possible the seals on the arm or the arm are damaged. The crank seals will NOT be an issue, there is no chain oil behind them!

Frammos idea of pumping the tank up a bit is a good idea, easier on the saws with rubber pickup pipes but possible by pushing a bit of big fuel pipe on to this arm union connector (you will recognize it when you see it)!

Sometimes you can fill up the oil tank with Petrol/diesel and if the leak is bad, it will come out a lot faster making it much easier to see.

Not much else to recommend, I wasn't being funny in my earlier post, sometimes it comes down to strip and diagnose. Damage through a mechanical failure rather than wear are difficult to diagnose unless it is a common failure!

 

[Estatesman]

Cheers for that . I’ve got a good idea of what I’m looking at now. I will check all that out, thanks. 
There is oil around the joint of the oil suction hose and pump which I am going to look at tomorrow too. Only had time today to strip it down tonight.

Thanks again

[Estatesman]

This is what I reckon caused the oil leak. The metal flange must have separated from the clutch when it overheated and sheared the elbow connection of the oil pump leaving a small gash. Parts ordered and fingers crossed.

Thanks for all the help .