old evinrude vent/drain screws

[Squeakit]

I want to replace the vent/drain screws on my 1957 Evinrude Fisherman 5.5hp lower unit, but I have purchased 5 different sets of screws locally and they have all been too large in diameter to fit down into the recessed holes in the gearbox. Everyone says these are the standard OMC replacement screws. Are the older screws slightly smaller or do I have a weird lower unit? Can anyone with an old Fisherman shed some light on this?

 

[Joe Reeves]

Re: old evinrude vent/drain screws

Squeakit.... That got me curious so I checked my remaining stock. The later drain screws that incorporate a "O" Ring have a thicker head, not wider, just thicker. The eariler ones that use a nylon washer are slightly thinner. Why are you replacing them?

 

[Squeakit]

Re: old evinrude vent/drain screws

Joe - thanks for replying. I'm replacing them because the screw slots are kinda buggered up from someone using the wrong size screwdriver I guess. The problem is that the newer screw heads are just a little too large in diameter to fit down into the recess. It's an extremely small difference but prevents me from using them. The original washers were a fiber material and the new hard white neoprene washers dont seem to fit right either. I put the old screws back in and used O- rings and teflon tape on the threads. Haven't tested them out yet. Would still like to replace the screws.

 

[oldboat1]

Re: old evinrude vent/drain screws

I don't think the new drain screws would protrude out far enough to make any difference in operation. You might try using the plastic washers after you heat them to make them more pliable -- might allow the drain screw to fit in a little deeper. Drop them into very hot water for a few minutes before use.