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Lower unit drain plug threads

pbrown

New member
I'd like to pressure test

I'd like to pressure test my lower unit. It does not sound that hard to make a little pressure gauge. But I need a fitting that will screw into the drain hole. The only recomendation I've seen is to cut the end off of a fill pump and use it. Does Anyone know what size the hole is and what the thread pattern is on a '89 40 hp Merc? }
 
3/8"-nc ---I made my own p

3/8"-nc ---I made my own pressure test unit years and years ago ----teed in a shreader valve and use a bicycle pump for the pressure.
 
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