Plug Problems--Bilge Pump Works

[followme21]

So we have a 84 Century, Merc-5.7, that we have used now for 8 years..no major problems. I have been noticing that it seams to be taking on more water then I felt it should when I pull the plug, so last time out I decided to get a new plug and the base that the plug goes in. Ordered it, and installed it, when I took the old one out it had two wood screws that did not seam very tight and the third screw was a very long machine screw. So I siliconed up the new base and installed three new, a size bigger, wood screws, they all tightened up very good. The next day we went out and after about 2 hourse or so the boat was full of water, I'm talking full. After running the bilge pump enough to get the water level down below the crankshaft, I have never in the 8 years had to run the pump so was very excited when it actually worked, I was able to get back to the dock and onto the trailer, As it was heading up the ramp I could see water coming out from around the base of the newely installed brass plug base. Now the silicone I used was not marine grade it was simply a acrylic latex that says it is waterproof. When I got home and removed the base no silicone was there, it had all washed away. I plan on getting a good marine grade adhesive/silicone and reinstalling...Should I make a rubber gasket? or will silicone be enough????

Also regarding that machine screw that I removed from the old base...after inspecting inside the bilge area I found an electrical wire that appears that it was hooked to that srew..It looks like a ground wire that ran from the plug base up the the transom, there are a couple of other ground wires on the transom in the same spot... I will hook it back up but why does the plug base need to be grounded??

Thanks for reading and responding..Its a little long.

 

[Lrider]

Re: Plug Problems--Bilge Pump Works

to quote - bifflefan who took the time to explain this to me - Regarding 3M - 5200 vs 4200 - there is 5200 fast set and regular set. Fast set is about 3 to 5 hours. regular is like 7 days cure time.5200 is almost impossible to get apart once set. it for permanent repairs the you dont want to take apart again.
4200 I cant remember the set time.
4200 you can take apart and is reasonably easy to clean off when you do. It like 5200 is good fro above and below the water line.
4000 is for above the water line only.
The PO of my boat also used caulk on some things. I cleaned them and used 4200 on them.
As for the little holes, there are various ways for deal with this. 1 dab a bit of 4200 on a stainless steel screw and put the screw in the hole. Not pretty but works. Or you can install a fake wire and something on the bottom so it looks like it should be there

Be Well

 

[fishrdan]

Re: Plug Problems--Bilge Pump Works

Don't use silicone, but even though you did I don't see why there was such a massive leak, unless the silicone was bad and didn't cure. I've had bad silicone before that looked OK, but never cured.

I would use 3m 4200 marine sealant on the drain plug base (garboard drain?) and mounting screws, jam a bunch of it up into the screw holes also. After securing the base, clean up the squished out sealant with paint thinner.

(FWIW, I used 3M 5200 on my garboard drain's base as I never intent to take it off the boat. If I ever have to it's going to be a real bear to remove...)

4200 and 5200 are moisture cured, so leaving a wet towel over the part will accelerate the cure, 1 or so day instead of 7 days for the 5200

 

[followme21]

Re: Plug Problems--Bilge Pump Works

Yea thanks thats what I though about the silicone.. it wasnt gushing in but we were on the water for close to 2.5-3 hours before it really got bad.

Any thoughs on the ground wire I described in the orignal post?

 

[fishrdan]

Re: Plug Problems--Bilge Pump Works

Any thoughs on the ground wire I described in the orignal post?

I'd guess it's to electrically bond the metal base to avoid corrosion.