Blue plastic drain plugs on Cool Fuel 4

rondds

Well-Known Member
Oct 3, 2006
8,859
Jersey Shore
Boat Info
2001 380DA
Engines
Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
I have had two of these break and the same CF unit on the same engine (stbd) inside of a year. I can't figure out why...it is not in a spot that's susceptible to being stepped on and I've done no work on that engine that could have led to possible breakage. Thwre are many others scattered around both engines that have never broken. I dont use them to drain the motors (I use antifreeze for winterization) so it's not getting fatigued from over use. Anyone else experience this?
20180803_152148.jpg
 
The heat from the engines gets to them over time and they get brittle. As far as the other ones scattered around... Most likely they are there when a mechanic dropped them while trying to install and falling into the great abyss below the engines. It's easier/faster to get a new one than to try and fish out the old one.
 
Hi Dennis. Something is fishy with this one. Second time in a year it sheared off. And the many others on both engines never had an issue in the 6 seasons I've owned this boat.

When I said there were others scattered around I meant there are several spots where Merc has installed these plugs where water can be drained, not that the ER floor was littered with broKen remains LOL!

As for temps, this particular one is sort of a "first stop" for sea water. It is fed by a T in the line that comes right off the raw water pump. So the water that enters this thing is 70 to 80*

I'm thinking it's a vibration issue. The wing leans against the brass fitting of the fuel line when fully tightened. I think that after a while it gets rattled enough to cause a fracture.
 
Oh, I gotcha now, Ron. Yes, I misunderstood what you are saying. I think your theory of vibration against a harder material makes sense. In your boat... the piece that contains the female fitting for the plug... can it be rotated a bit to avoid contact of the plug ear and brass fitting? Or... maybe just trim the ears a tiny bit so they don't contact the brass fitting? FYI... if you cut two slots into a 1/2" deep socket, you don't need much "ear" to remove the plug, should you ever need to.

I think I remember seeing someone on CSR advertising about those SS plugs... maybe the same person that's on ebay? I'd still want to make sure things weren't touching, though. Probably would be a non-issue, but better safe than sorry.
 
Good idea about dremel'ng the ears off! Didn't think of that. But I've already ordered a SS plug from McMaster Carr. These have o-rings as are these particular fasteners that I found on McM-C. I'll load it up with never-seeze. I believe they're plastic b/c the CF module is aluminum - dissimilar metals in an electrolytic environment is probably a no-no. Maybe I'll do the dremel thing...
 
Can you post the link where you got the SS plugs from... Would love to buy them as well for this winter...
 
This is what I ordered https://www.mcmaster.com/#92205A523

But hang on before you buy. It arrived today and the 0-ring looks like it will sit in a recess of the hex head. Not sure if it'll make up against the CF module enough to get a good seal if it's recessed. Let me try it out and I'll let you know.
 
Ty so much Def Appreciate it... I was also worried about the Corrosion with the Aluminum and the SS..on the fuel cooler....You think it will counter act?? And freeze up in there....
 
I'm not sure. I guess eventually it would seize. My greater concern is galvanic corrosion caused by the dissimilar metals,which could lead to perforation of a $1000 fuel cooler.

To be honest I'd just as soon epoxy up the drain. I don't use any of the blue plugs since I run pink antifreeze through the engines for winter lay-up.
 
Ty so much Def Appreciate it... I was also worried about the Corrosion with the Aluminum and the SS..on the fuel cooler....You think it will counter act?? And freeze up in there....
I'm still using the original blue plugs in my 280DA, 13 years old. Finger tight with a bit of spit for lube when re-installed....don't have to worry about corrosion.
 
Learned about these plugs the hard way. At a marina having dinner, looked over and bilge was pumping, which it normally does not. Went to investigate and the same one on the fuel cooler was sheared off and leaking. Just happened on its own, nobody around. Guess I could have bumped it at some time and cracked it. Ended up tappin Nothing left to grab a hold of. What a pain. So now carry a set of easy outs and a few spares. Fellow boater says he exercises his on occasion to prevent seizing up. Though of the ss ones as well and from what I read they work great until they corrode - leak and require replacing the module.
 
Woody, not worrying about the blue plastic ones corroding. It's a metal plug that I'm concerned about.

Korkie, that seemingly "spontaneous combustion" breakage that is so perplexing. Same exact thing happened to me..two times now, and on the same fuel cooler.
 
Woody, not worrying about the blue plastic ones corroding. It's a metal plug that I'm concerned about.

Korkie, that seemingly "spontaneous combustion" breakage that is so perplexing. Same exact thing happened to me..two times now, and on the same fuel cooler.
That was my point. There's got to be a gazillion of those blue plugs in use, maybe more. Most folks aren't having breakage problems, somehow they're getting abused I'd think. It sounds like you identified what's doing yours in. Do the blue plug modification and try it one more time, you might not have to worry about corrosion then.
 
^^^ that looks like a good deal for plugs.......

Would you put something on the threads like never seize if you used the stainless steel ones?
 
Some never/anti-seize products have metals in them... not good. Best product for this purpose would probably be Tef-Gel. But my vote is to mod the blue plug.

Besides... those stainless ones... looks like their "ears" are at least as big as the blue ones and would likely have to grind them down, as well, for this application.
 
OOOOO! Those are purdy. Same price as the crappy blue ones too.

Yeah, I think I'm gonna dremel off half an ear and see what happens.
 

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