Blue Drain Plugs

aero3113

I had one of the blue drain plugs snap on me. It’s one that I didn’t replace when I bought the boat. It was new last season, it came with my new cool fuel pump. It seems like whatever ones I bought are much better than OEM. I tried to chip it out but wasn’t working. I was able to tap a screwdriver into it, heat with a little torch and it screwed right out.

LaRea

You need Hardin Marine stainless steel plugs.  I've been patiently waiting for one of my plastic plugs to break so I can replace them all, but no luck so far.  

https://www.hardin-marine.com/p-81080-stainless-steel-sea-pump-drain-plugs-mercruiser-22-806608a02-8m2000874-5-pack.aspx

aero3113

@LaRea , I’ve seen them. But always wondered about dissimilar metal corrosion, especially in salt water.

YYZRC

Right. And they probably leak like their pumps!! 

aero3113

LoL, ouch @YYZRC. I’m telling them you said that! 😂

YYZRC

Keeping it real. Real @rando3113

mattie

Those Hardin plugs are cool lookin’.

Bling bling.

Spyderweb

I bought 5 of the stainless plugs last year.  Left them for marina to replace 5 of the blue ones this spring.  They did it but service manager warned me this spring there can be trouble with dissimilar metals corrosion, and I’m in fresh water.

boatman37

I was going to order those SS plugs but wondered about the dissimilar metals

LaRea

The stainless steel bolts don't cause corrosion.  It's a bronze part.  Yes, stainless steel is more noble than bronze, but the difference isn't huge.  

aero3113

@LaRea , but what about all the other plugs on the engine?

LaRea

I'm guessing any part that has raw water running through it will be made of bronze, which means it can tolerate stainless fasteners (and drain plugs).  

aero3113

LaRea said:

I'm guessing any part that has raw water running through it will be made of bronze, which means it can tolerate stainless fasteners (and drain plugs).  

The one that broke on me in the above pic is for the cool fuel, all aluminum and has raw water going through it.

aero3113

Also, isn’t the thermostat housing steel? That’s raw water on my engines also.

LaRea

I stand corrected ... would not use them on a component made of aluminum.  

YYZRC

So it begs the question. The arch is aluminum and the screws used to secure the u channel are stainless. How does one prevent corrosion?

aero3113

YYZRC said:

So it begs the question. The arch is aluminum and the screws used to secure the u channel are stainless. How does one prevent corrosion?

@YYZRC , read this. It explains it pretty well.

https://www.anzor.com.au/blog/stainless-screws-in-aluminium

aero3113

Plus the “U” channel is a barrier so the head of the screw isn’t touching just very little of the threads. Need to find some of that Tef-Gel !

aero3113

Yes, you still get some corrosion but not nearly as bad if it was aluminum screws into stainless.

Dream_Inn

Just change the blue plugs every couple years or so and never a problem.  I have a buddy that went with the hardin plugs and they actually can loosen up pretty easy.  He has had two of them come loose and leak.  He has not been that happy with them.