Slow leak at exhaust riser drain screw

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Jun 12, 2009
5
2 30 Alexandria, Va
The drain screw on the aft of the exhaust riser on my 1990 has started a very slow drip when screwed in. I fear it is stripped. It had not been removed for probably 10 years until I needed to twice for a 30 second plus nonstart. Today it started a very slow leak that is worse when she is cold. A couple of options, it seems, perhaps someone has a better idea:

1. Since you can get by without removing it often, use a tiny amount of a liquid gasket product to finish the seal and hope you can break the tension if you need to drain the riser box in the future. Downside, you'll have to break the seal and hopefully not damage the screw in doing so. Perhaps only apply to one thread.

2. A small wood plug. This seems like a really bad idea.

3. Buy a new screw drain. Problem: If the female side is also stripped, this will not solve the problem.

Would love to hear how someone else might have dealt with this before.
 
Feb 26, 2004
23,050
Catalina 34 224 Maple Bay, BC, Canada
Definitions & terminology

U wrote: drain screw on the aft of the exhaust riser

I am unfamiliar with that description. Please confirm that you have a Universal M-25 series diesel, which is what these comments are based upon.

I am not aware of any drain screw on the riser. The only drain screw is on the MUFFLER, the fiberglass box that the exhaust riser is connect to.

If you are, indeed, talking about the muffler, then your options are well presented and thorough.

Option 2 - I agree makes no sense.

Option 3 - Only you can tell, but if it is stripped, I agree it won't work.

That leaves us with Option 1, which made the most sense to begin with.

In the 11 years I've had our boat, I have never had to drain the muffler because we've never had a reason to have to crank the engine more than 30 seconds. We built a stable electrical system to assure engine starts. We never, unlike many C30-ers, use the decompression lever.

The gasket material should be flexible enough to, first, provide a good seal, and second, separate when you need, if ever, to remove it.

Make sure you use high temperature gasket material.



 
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