I am in the process of finishing my basement and I have a total of 4 drains in the floor. The house was built in the 30's. I have never, ever had any water in the basement. I do however have a strong sewer gas odor coming out of the drains at times (I suspect when the traps dry out? ). I was wondering what I can do to seal them off so I can finish the basement and eliminate the nasty odors. Also, I have one mortar joint that gets damp after a heavy rain. If I dig out that mortar to repair it, what type would you recommend I use to replace it?

I have one mortar joint that gets damp after a heavy rain. If I dig out that mortar to repair it, what type would you recommend I use to replace it?
Are you quite sure it's mortar? What material are the pipes and what do they do?
As for your floor drains. Block the drains with damp rags to seal off the drain and fill the opening with hydrolytic cement to a level floor. Good luck, Tom

Sorry, I should have been more specific... The mortar is about two rows up on the back basement wall. It's like the mortar was painted over several times, and on a rare occasion, it will become damp if we have a really hard, extended rain shower. I'm wondering what I should use to replace the mortar if I dig it out from between the block...

With the drains, there's no issue with just blocking them off? The hydraulic cement will prevent future odors from leaking around it?

Sorry, I should have been more specific... The mortar is about two rows up on the back basement wall. It's like the mortar was painted over several times, and on a rare occasion, it will become damp if we have a really hard, extended rain shower.

I'm wondering what I should use to replace the mortar if I dig it out from between the block...

With the drains, there's no issue with just blocking them off? The hydraulic cement will prevent future odors from leaking around it?

I'm wondering what I should use to replace the mortar if I dig it out from between the block... '
My bad! I was thinking pipes and not cement blocks. If you have moisture that seeps past the joints in the blocks during a hard rain you can seal those joints with
Hydraulic cement also. But if ground water has you concerned why in install a french drain or build your own dry well,(see images) and direct the run off away from the house?

The hydraulic cement will prevent future odors from leaking around it?
For additional insurance fill the floor drain traps with cooking oil or anti-freeze. Good luck, Tom