If you mean replacing the gasket, usually, yes. But if it is fairly new, came off easily and didn't tear, you could try a non-hardening gasket sealant on re-installation. Replacement gaskets are flat - they mold to the cam shaft bump.

What you should check is the flame trap which, when clogged, can cause excess engine pressure and oil leaks.
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1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

Just make sure you use a Volvo replacement gasket. I have used Elring kits and Felpro. I always seem to have some sweating of oil from them showing up some place with those.

If you use sealant in the front corners per the manual. Don't use very much. You don't want any extra to get to squash out around into the oil galley. The stuff doesn't cure right away.

If it is a good gasket I doubt you really need to use sealant. The gasket is suppose to fill surface blemishes. The gasket material fibers are suppose to be laid to crisscrossed and block seepage.

I just push the cover on by hand few times to flex the gasket to stretch to get over the front cam surface. Then put it on with the nuts then work them down as evenly as you can. Then run it up to proper torque.

As far as replacing it every time. Yes, unless you are just doing adjustments and can stand the leakage until you can put it on permanately. Extended time would not be advised.

Phil

I assume you mean the cam cover, and, yes, the gasket needs to be replaced every time the cover's off. Don't forget some goo in the corners.