STIHL MS440 Reassembly Questions

[FamilyTradition]

All, good afternoon. I'm reassembling an MS440 that was given to me with a lightly scored piston/cylinder. The issue causing the scoring was fuel related. With that said, I've invested in all STIHL OEM parts for the rebuild: OEM piston, fuel and impulse lines, NOS boot, OEM tank vent and fuel filter (large end), OEM cylinder gasket, and more. I even invested in the STIHL tool for circlips. My question is this: do I use Yamabond or similar sealant along with the OEM cylinder to crankcase gasket, or do I simply use the gasket itself? I cannot remember/figure it out and am seeking help. Also, in which direction do I place the gasket: raised surface up towards the piston or down towards the crankcase?

I haven't worked on many STIHL's before, thus the question. I hope everyone is well and thanks for any help and assistance. Max.

 

[L34]

Never done an 440 but if same as 066 indent down(towards crank)
Some use sealer,some don't.
I do,Permatex.

 

[lone wolf]

Curvature on the gasket down you dont need the sealant but put it on if it makes you feel better.

 

[Yukon Stihl]

What ever method you chose...
Vacuum and pressure test once you have it reassembled

 

[drf255]

No sealant if oem metal, I’ve never had one leak.

Convex up on that gasket (bulging towards the jug). That being said, I’ve done backwards with no issues, but the bulge should be up. They are flat when you pull them out used, so unless the bulge was up from the factory, they’d never gat flattened.

Vac testing on the 044/440 is tougher than most. The crank spacer on the clutch side inherently leaks a bit. Grease it up before you slide over the crank. You really need to snug the clutch down before you test in an 044/440 unlike other saws.

 

[Mad Professor]

If I use any sealer on gaskets only a very thin film. Put on some nitrile gloves and just a thin smear on the gasket as you pull it between your fingers/thumb.

 

[Nex]

I put together a 440 quite recently. Happy to help if you need - feel free to shoot me a PM.