Unclogging drain in 1956 Evinrude 30hp water LU

[NeilDaCosta]

I just pulled off the lower unit from an engine I bought; cleaned it up and replaced all the seals. I need to clear the drain that drains excess water/gas from the top of the LU(not where it is filled with oil). I cleaned out as much gunk as I could see from the top and all the dry dirt from the small drain hole on the side. But both access holes make 90 degree turns and I can't get it cleared past there.

Here is what I have tried:

letting carb cleaner sit in there
trying to get a guitar string to make the angle
compressed air
Letting penetrating oil sit in there
Knocking side with mallet

Anyone else have any advice on how to clear it?

All I can think of is some sort of high powered drain clearing product(that won't effect metal)?

Or heat? Although I wouldn't want to go overboard with heat.

Any insight is appreciated

 

[AlTn]

got a pressure washer or a self serve car wash nearby?...