MS 180 Crankshaft Seals

[paul99]

After just under 18 months of serious abuse my trusty MS 170 / FT 180 hybrid finally let me down. I'd worked it all day fencing but had noticed it had gradually developed all the usual symptoms of an air leak.On testing sure enough there was an issue...




It was interesting that it wouldn't hold a vacuum but would hold pressure until you touch the crank.

Anyway I've stripped it down removed the crank and pulled the bearings ready for a set of 6002 skf replacements but when it comes to the seals the ipl lists two possibilities...

9638 003 1581 and 9639 003 1585 the first one being double the price of the second??? I did a bit of googling but couldn't find anything to explain the difference so does any one out there know what the deal is with two part numbers?

 

[HarleyT]

Here is the bulletin covering the seals.

 

[paul99]

Here is the bulletin covering the seals.

That straightens that out I can use the cheaper seals then. Thank you HarleyT

 

[smokey7]

Is it my eyes playing tricks on me or is your crank moving as in radial slop (bad crank bearings)? Is this onebof those cheap long blocks that come preassembled?

 

[MnSam]

It was interesting that it wouldn't hold a vacuum but would hold pressure until you touch the crank.

An "aha" moment for you.
Your crank should always be played with during suckage.

 

[MnSam]

Is it my eyes playing tricks on me or is your crank moving as in radial slop (bad crank bearings)? Is this onebof those cheap long blocks that come preassembled?

Good eye, true that.

 

[paul99]

Is it my eyes playing tricks on me or is your crank moving as in radial slop (bad crank bearings)? Is this onebof those cheap long blocks that come preassembled?

No it's not your eyes it's definitely bad crank bearings that is the cause of the problem. It is one of those cheap Chinese pre assembled long blocks - it was the cheapest & quickest way to get that scrap saw up and running at the time and to be fair its done a lot of work since. With a lot of that cutting in bigger wood (14"+ hardwood) that it was never designed to be used for... silly really given the choice of more suitable saws I have available but with a sharp, well cutting chain it's hard to put down such a light saw after the limbing up is done.

The slop in the bearing is noticeable in the video but now I've pulled them off the crank they actually look good with no visible signs of damage they still turn smoothly with no notches and no play noticeable. I'm guessing they are simply just worn which surprises me a little, even given their Chinese heritage. With the big end bearing, small end bearing, piston and cylinder in perfect condition I'm ruling out it being an oiling issue maybe it's just one of these bearings...




Whatever the case it will be getting some decent replacement bearings new seals and we'll see what happens....