Seal for crankcase

[Racer]

Hello guys, i have question about crankcase assembly. For this operation i need use seal with gasket or just gasket enough?

 

[Agent Smith]

When i put bottom ends together, i pull the dowel pins, give both case half gasket surfaces a few swipes across my flat plate with 220g stuck to it to true up the surfaces. I do smear a very very thin layer of 1184 on the crankcase gasket and assemble away. Thats probably overkill as the factories assemble them with a dry gasket but any saw i touch is always old, well used units with some warpage so i feel a little sealer is helpful.

 

[Woodslasher]

I use Copper Coat on my paper gaskets just to be safe.

 

[jacob j.]

It's a good idea on older saws that have a long, thin run in the case underneath the muffler like the Stihl 064/066/084/088, Husky 281/288/394/395, Efco 999/Oleo-Mac 199, etc.

 

[Sloughfoot]

Helps hold them in place while reassembling, if nothing else.

 

[Stump Shot]

Some saws such as like in the manual for the 372xp actually call for grease to be applied. I believe the thinking is so if the case shifts, the gasket doesn't tear.
Case disassembly can be a mess when sealant is present as well. The copper coat spray is a good option or even spray paint can work well if applied still tacky without much of an increase in thickness. (usually about .001")
Also as previously mentioned, truing the case halves is most important for good results. I have not seen a set yet that doesn't have a little warpage to them.

 

[Vintage Engine Repairs]

Permatex Aviation form-a-gasket #3 is my go to for any gasket dressing.