Fixing leak in genny muffler

Spyderweb

At bottom of generator muffler is a screw, that I assume is to drain the muffler for winterization.  Couple of years ago I noticed water leaking from it.  It no longer screwed in tight, so I wrapped it with plumbers tape, it took up the slop and stopped the leak.

Checked this earlier in the week and big leak again with genny running.  Now hole is so stripped that tape no longer works.  Muffler is a fibrous plastic material.  Would it be appropriate to tap larger threads and put the next size screw in to seal the hole?

Spyderweb

No one with ideas on this one?

YYZRC

I removed my genny exhaust the other day. It seems to be made from fiberglass. I am not sure that you could tap threads into it as it appears to be very thin (1/8" or less). I would be inclined to use a step bit to clean out the existing hole and use a new appropriately sized bolt.

Spyderweb

So essentially the new bolt would make its own threads?

YYZRC

That's how I would tackle it.

Alternately, you could try some epoxy on your current bolt. I might attempt that approach first.

There was a lot of water in the muffler when I removed it. Definitely learned a good lesson about winterizing and the importance of running a lot of antifreeze through the genny before winter storage. My guess is that you had some water left in there one winter and it pushed the bolt out.

Spyderweb

I thought maybe mechanic used power screw driver to reinstall and stripped the threads.  

Wouldn’t using epoxy risk tightening it too much making difficult to get off to winterize?

YYZRC

I have never removed the bolt for winterizing. Maybe @aero3113 can chime in on how he winterizes his.

Spyderweb

I don’t do mine so I don’t know how the mechanics do mine.

PickleRick

You can get NPT taps at your local harbor freight.  Then drop by your favorite hardware store and get both a plug and proper pilot drill bit size for the tap that is the next size up.

I've never tapped fiberglass but I'd be careful as it's a little brittle.  Go slowly with the tap and back out often to keep the threads clean. Install with a little sealer. 

Good luck!  

Rich_

Retap next size up and new plug.

worst case glass/epoxy over the drain hole and always use lots of antifreeze for winterizing.

Dream_Inn

So, I have never removed mine for winterizing (17 years worth).  I do run two gallons of pink stuff thru mine when I winterize.  It has a strong pink color out the exhaust when complete.

aero3113

YYZRC said:

I have never removed the bolt for winterizing. Maybe @aero3113 can chime in on how he winterizes his.

I never removed that bolt to winterize. I remove the hose off of the seacock, stick it into a low bucket full of antifreeze and run the generator. Once the antifreeze is sucked out to almost empty, I shut her down and leave it till spring.The picture is when I ran it at the house with a water hose feeding the bucket.

YYZRC

Dream_Inn said:

So, I have never removed mine for winterizing (17 years worth).  I do run two gallons of pink stuff thru mine when I winterize.  It has a strong pink color out the exhaust when complete.

aero3113 said:

I never removed that bolt to winterize. I remove the hose off of the seacock, stick it into a low bucket full of antifreeze and run the generator. Once the antifreeze is sucked out to almost empty, I shut her down and leave it till spring.

 This is what I do as well.

@Spyderweb I would epoxy the bolt in place and move on. I would sand down the outside surface of the muffler around the hole, cut a small circle of fiberglass mesh maybe 1" in diameter, put the bolt through it, and epoxy it in place. Trying to tap the thin fiberglass seems dicey.

rasbury

Could you put an insert/helicoil in it so you can continue to service? Is it under any pressure?

LaRea

Time to upgrade to a 2-stage muffler.  I looked into them a few years ago, but with a working muffler, it didn't fit the budget.  

Liberty44140

Yes they are fiberglass. I had a crack in one years ago on a diesel sailboat, same size as yours, patched it with west system and cloth, and ran it for several years on my dads racing sailboat. If it really bothers you these are not that expensive and easy to replace but you can definitely either put a patch over it to seal it, or just screw in a larger screw. Maybe do both. This is not that big of a deal. I would probably drill it out larger, fill it and re drill and re use the screw. 

Spyderweb

Up to the boat this week and thought I'd tackle the leaky muffler.  Was going to try and use a larger bolt, though I had nothing to ream out the old hole.  Found a few choices in my tool box.  The 1st 2 turned out to be same size threads, loose and sloppy. The 3rd was a thumb screw off the bimini of a former boat.  Turned out these threads were the same size too, but when I screwed it in, and hit the non threaded part, it snugged right up.  Started genny and no leak.  Ran the genny out on the water later in the day.  Checked afterward and maybe a drop or 2 of water had come out.  Bolt was still tight.  

If anyone still wants to take it out, it's easier with the thumb screw than trying to get a slotted screwdriver head on it in the awkward location that it is.

I think I'm good.  Thanks for your ideas.