FS80 (4137) how to split the case?

[Luven]

Hi all, am new to these machines and have been watching loads of @Vintage Engine Repairs and other youtubes but can't find many where anyone has actually split the crankcase on these - anyone had experience or suggestions for how to DIY'it?
i don't have much in the way of pullers etc but can try to fudge something...thanks for any help you can offer.

 

[stihl #1]

Special tools are required to do it without a hammer or damage, both to split the case and push the crank out of the bearing, as well as to pull it all back together, again without hammering. I have never tried to do it without the tools so I am sorry I am not helping you any. Just curious but why are you trying to open it in the first place?

 

[stihl #1]

See page 15 to start.

 

[Luven]

Thanks for the confidence boost! Pressure tested the whole thing and sprayed soapy water on it to clearly see a leak between the crank halves... Assume I could probably bodge it up with some glue/paint/silicone on the outside but not ideal to say the least...

 

[hacskaroly]

Thanks for the confidence boost! Pressure tested the whole thing and sprayed soapy water on it to clearly see a leak between the crank halves... Assume I could probably bodge it up with some glue/paint/silicone on the outside but not ideal to say the least...

There are ways to split the case with just a hammer and screw drivers, however, if not careful, you risk gouging metal and mushrooming over the crank shaft ends (threaded part).

I split two saws and put them back together this way and it was a pain in the rear! I ended up cutting wood planks to put around both halves and use cargo straps to cinch it all back together...very redneckish. I have since bought a case splitter and another tool to pull the cranks through without the need to heat anything up or beat on it, much more pleasant to work on.

If it is just a small area that is leaking, you might give JB Weld a try, clean the surface as best as possible, push the JB Weld into the seam, let it dry and then put some more over the top of that and let it dry and give that a try. It might help you get by until you get the tools to split it or get a new unit.

 

[stihl #1]

Like this?

STIHL used a grey RTV sealant back then and it is common for it to start leaking with age. The FS 80 went out of production in 2009. Somewhere in the early 2000's STIHL started using DIRCO red high temp RTV which is much better. Never tried JB Weld as suggested but it might work.

 

[hacskaroly]

STIHL started using DIRCO red high temp RTV which is much better. Never tried JB Weld as suggested but it might work.

I agree, if he can split the halves, Dirco Red will be the way to go. If he wants to try to patch from the outside, JB weld should work for that application.

 

[Luven]

Thanks guys - it's actually got the red on it already and that's failed but still, if it's anything in the order of a decade, then can't blame it.
Actually, where is the serial number on these things and how can you tell the age? can't find anything on the motor which i would think was unusual....
I'm up for the challenge so will try to work something out re splitting.

On a separate note, to reassemble the MS661 also on the table, i'm trying the method Matt O demonstrates to pull the crank through - will post pics if i can get it to work....

 

[hacskaroly]

Thanks guys - it's actually got the red on it already and that's failed but still, if it's anything in the order of a decade, then can't blame it.
I'm up for the challenge so will try to work something out.
On a separate note, to reassemble the MS661 also on the table, i'm trying the method Matt O demonstrates to pull the crank through - will post pics if i can get it to work....

Yeah, give the JB Weld a try, it should harden up enough after 24 hours to give it a try (compression test - or attempt to start).

I have Matt O's tools, they work really well, I have used them on about 7-8 saws so far and they are awesome!