I have the newer Merc system with the Blue plastic drain plugs. On my Port engine I was getting a drip from the drain plug. I ordered new ones and installed... It went from a drip to a slow stream when the engine is running, then a slow drip while off.

Any advice? Should I put Teflon tape on it too?

do you have the o-ring on the plug? if you do your leak isn't the plug....

Are you sure it's the blue plug? Is it a 496? The air acutators have a spring that will go bad after a while.

If you are certain it's the blue plug and it's fitting, are you certain you don't have an old O-ring jammed up in there somehow?

There is no spring that I can tell, it's a small blue plug with an O ring. I was sure to get the old o ring out but I will re-check.


It looks like this:

did you get all of the remnants of the "old" plug out of the manifold before installing the new one? We had to dig the busted off pieces out before installing the new plug. I realize this sounds stupid, but it's easy to miss the pieces that break off up in the manifold.

Is this a 496 with the air actuated drain system? If so, it may be the piston that moves up and down to open/close the drain. That piston has two o-rings on it. If one or both of those o-rings are broken, you will see a constant drip/stream leaking directly down from the water pump. I've been there! Simple fix. The piston is held in place with a snap-ring. Pop off the snap ring and lift out the piston. You will see the broken o-rings on the piston, if that is what the problem is.