Help Stihl MS460 not starting

[Muddy42]

@spudulike @pleasant we've removed the cylinder and its not pretty. There are pieces of metal everywhere and deep scoring on a hidden inner side of the cylinder.  I think a bearing has exploded somewhere (and probably what was making the ticking sound for a while) but we won't know for sure until we crack the case to assess the damage. Hopefully the crank is OK, but as a minimum I'd be looking at new bearings, gaskets, seals and another meteor piston and cylinder - about £150 in parts alone, so probably still worth it.

[spudulike]

It may well be the big end. Check for play in the bearing - Up and down not sideways. You can usually push the con rod big end to one side with the big end cage pushed the other then rotate the cage round with a craft knife or similar. Look for cracks and missing bits on both sides of the bearing cage.

Not a nice outcome but a good learning curve for the future.

I think your £150 maybe a pretty light estimation.

[Muddy42]

23 minutes ago, spudulike said:

It may well be the big end. Check for play in the bearing - Up and down not sideways. You can usually push the con rod big end to one side with the big end cage pushed the other then rotate the cage round with a craft knife or similar. Look for cracks and missing bits on both sides of the bearing cage.

Not a nice outcome but a good learning curve for the future.

I think your £150 maybe a pretty light estimation.

Thanks. Lets see. We’re going to crack the case next week so no decisions made yet. Ive never done this before (but my friend has repaired a few and has the tools needed) so it’ll be fun to see. Yes I presume cracks would be a no go.

 

I guess thats the risk you take with old saws, but hey my MS261 has needed expensive parts too so you cant win.

[Trailoftears]

I'm sorry to hear the oucome.But if you can  get it done for the budget,I guess its viable.After all-whats a new equivalent now-4 figures no doubt.

[Dan Maynard]

Other option being good secondhand 461 in the region 5-600, if you can find one you trust.

[spudulike]

I left out one thing, the bottom of the con rod (Big End) will often blue up if it gets pretty hot. You can do all the tests I mentioned to verify a failed big end without splitting the crankcases. Hopefully one of your mains has grenaded as it is a bit cheaper than a new crank.

The crank is shared with the 461 - I repaired one with a secondhand 460 crank saving the owner a decent amount of dosh in the process.

[Muddy42]

Right so several weeks later and I can give a successful update.  So I took off the cylinder again, thinking I was going to need to crack open the case and investigate the bottom end.  I don't know how we missed this but when disassembling the piston (for the first time) there was a broken circlip.  This was the source of the metal that caused the scoring in the cylinder.  The big end and bearings felt OK.  We swabbed out the bottom of the crankcase to check for debris.

 

I fitted cheap Chinese cylinder simply to vac and pressure test.  It passed, so I've now fitted a second meteor p&c (and new stihl piston circlips) and sent two tanks of 25:1 through it in the logpile.

 

Two years ago and prior to a lot of use, I fitted the first meteor p&c, using the original stihl circlips.  Maybe these were worn or I didn't fit these correctly, I genuinely cant remember?

 

The flywheel issue was fixed also with a torque wrench - maybe I didn't have it tight enough?

 

Sorry for all the many misdiagnosis - this thread isn't going to be that helpful for others! Its useful to have friends with more experience than me at fixing saws.  Still learning me.

[openspaceman]

6 hours ago, Muddy42 said:

I fitted the first meteor p&c, using the original stihl circlips. 

Strange, the few stihl saws I took apart the gudgeon pin circlips had no tangs.

[spudulike]

Yup, as OS said, Stihl never used tanged circlips but thanks for the update and glad the saw is up and running again.

[Muddy42]

like this? This is what the non broken one looked like.