Exhaust leak troubles

Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
I've had a persistent leak at the exhaust since I installed our new engine several years ago. It isn't a major leak, just enough to cause a little water in the bilge while underway. It's been a long time since I removed the back panels to look at it. Now I'm wondering how to go about curing it. Is it possible without removing the exhaust fitting at the stern?

IMG_6011.JPG
IMG_6015.JPG


The stern fitting is a 2" SS assembly from Vetus. Originally, there was a 1-1/2" fiberglass tube that the hose connected directly to. With the new engine, I needed a 2" muffler so I had to drill out the original hole and insert the stern fitting. VETUS stainless steel transom exhaust connection, check valve, 51 mm - Transom exhaust connections - Exhaust systems I had the installer do the work. Some remnant of the original tube is left as can be seen above the exhaust hose. I can't remove the hose because the muffler is locked in place and so is the Vetus flange. I can't tell if the water leaks from around the outside flange and thru the new drilled hole, or if the water leaks from the hose. The hose is double clamped, so I doubt it is the issue.
I think the orangish stains are from the leaking water. There reddish material around the cockpit drain was there before, I'm pretty sure. The same stuff is around the one on the other side, too. I couldn't get the cockpit drain off by hand so I left it unclamped for now.
 

Attachments

capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
I don't see a hose barb in that fitting to secure the hose to it and then clamp it. That would be my priority. If I'm not mistaken, take the fitting off, clean it up and check for dangerous corrosion. It appears to be 304, not 316 S/S. Then get it to a machine shop to weld the proper size nipple onto the fitting's inner end which you can then clamp the exhaust hose to.
When you replace the fitting on the hull, use underwater seam compound to bed it and through bolts. There's quite a bit of weight in the muffler and it must flex any loose connections in that line, which could create your constant leak.
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
Well, I am curious about the rust stains around the flange, but the specifications from Vetus indicate that it is 316 SS. Also, what are those 2 rings at the end of the inner tube if not a hose barb? (I'm looking at the Vetus link). That fitting has been in place for 6 seasons of relatively light use - 200 hours on the engine total.

The screws could be a problem, I suppose. Thru-bolts or machine screws would be an improvement if I can reach in there to secure the nuts on the inside.
 
Last edited:
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
A question, wish I had a solution, could the water be coming in from outside the boat. Does the exhaust drop down beneath the water when you are going WOT?
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
A question, wish I had a solution, could the water be coming in from outside the boat. Does the exhaust drop down beneath the water when you are going WOT?
Yes, the boat squats quite a bit. It is virtually submerged while running even at about 2/3 WOT. I tend to run at high RPM just about every time I'm going anywhere outside the channel, so the exhaust is submerged probably 75% of the time I'm running with auxiliary. It's just barely submerged and the exhaust is bubbling away, but it is submerged.
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
I know my boat had that problem. I was worried about possible water intrusion. It is not unusual. It could be a factor. Wondering about the seal around the exhaust port. Or perhaps you have another source of intrusion on the stern.
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
My general impression is that there is water leaking around the outer flange and that the bedding was not done very well. However, the muffler tube and the stern tube do not align perfectly, either. There is only about an inch or less gap between the muffler tube and the SS tube at the stern fitting. The flexible hose overlaps enough at both ends to get a good solid 2 clamps at each end, so even if the alignment isn't perfect, I wouldn't expect a leak from the rubber exhaust hose. Also, the hose is only 6 or 7 years, and should be fine. At least it looks like it is in perfect shape, and I don't see any defects with the clamps removed.
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
I know my boat had that problem. I was worried about possible water intrusion. It is not unusual. It could be a factor. Wondering about the seal around the exhaust port. Or perhaps you have another source of intrusion on the stern.
Well, I did have some concern about the other thru-hulls that are in that vicinity because they are all virtually submerged when the boat is running. If you look at the photo underneath from further back, it is pretty evident that the water comes from the exhaust port. The 2 cockpit drains appear to have some sort of red sealant that was used and I don't see any sign of a water trace from the port side. There doesn't appear to be anything coming from the locker drain or the bilge discharge either. I only get water entering when the engine is running, which makes sense anyway because all of those thru-hulls are above waterline when the boat is just sitting in the water.

If I had enough patience, I suppose I might try running the engine at the dock and watch for a leak while the boat isn't moving. But that would mean waiting for several months :banghead:I think that the logical course of action is to remove the Vetus fitting and make sure it is well bedded when putting it back together. My fear is that I can't crawl in there and get my hands on all of those parts with enough strength to get everything apart and then back together. Plus, I have no idea how they got that muffler in that space and I'm afraid that I will need to move it to remove the exhaust hose.
 
Last edited:

DArcy

.
Feb 11, 2017
1,691
Islander Freeport 36 Ottawa
That looks like a very challenging place to get at. You are probably correct, it looks from the staining as though the water is coming in from the flange on the transom exhaust tube. Re-bedding may fix the problem but you may need to put better through bolts on to get enough compression to seal.
There is staining around that cockpit drain thru hull so it could be coming from there. Isn't it a bit odd to have those drain thru-hull fittings below water with no seacocks?
 
  • Like
Likes: Scott T-Bird
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
That looks like a very challenging place to get at. You are probably correct, it looks from the staining as though the water is coming in from the flange on the transom exhaust tube. Re-bedding may fix the problem but you may need to put better through bolts on to get enough compression to seal.
There is staining around that cockpit drain thru hull so it could be coming from there. Isn't it a bit odd to have those drain thru-hull fittings below water with no seacocks?
I don't think the darker red color is staining from water intrusion. There is the same material around the other cockpit drain on the port side and it doesn't show the tracing of a water leak. It looks more like a sealant material. The lighter rust stain is the tracings from water and it originates at the exhaust port. It just happens to flow around the cockpit drain on the starboard side. and you can see it also further towards the center.

All of those thru-hulls, including the cockpit drains, are above waterline when the boat is still. They are below WL when the boat is squatting while underway.
 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
Looks to me at least some of that leakage is coming in through the bottom left hand screw (looking from the inside back to the transom) where the stain is kinda like a dark river, that screw is very corroded as well.
 

Attachments

  • Like
Likes: Scott T-Bird
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
Looks to me at least some of that leakage is coming in through the bottom left hand screw (looking from the inside back to the transom) where the stain is kinda like a dark river, that screw is very corroded as well.
Good eye! I think there may be leakage at each of those screws. I could try to replace them with machine screws and nuts, but it doesn't look like I will have a flat surface on the upper ones unless I remove the fitting and cut away the remnants of the old tube.
IMG_6027.JPG

here is another look with a better angle to see the top screw without shadow. I think there is some dark staining around that one as well.
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,758
Alden 38' Challenger yawl Rockport Harbor
Great photos, Scott! That makes it easy to see the situation. I don't think you have an leak from the exhaust hose connection. Wouldn't there be some carbon staining as well? Rust is insidious and tends to collect and grow in places like that where you can't clean it off. Could just be condensation working on the fasteners, clamps and stuff (no leak at all).

My 2 cents: Your exhaust outlet is secured with machine screws. Good! Take it off, clean it up, re-bed it and re-install(new screws). Then you can connect your exhaust hose back up, clamp (new clamps if they're rusty), unless you see a problem.
 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
Doesn't look like a whole heck of a lot of room to get in there, you might want to tie a recovery line around your ankles so someone could pull you out of there... you know just in case you cramp up.
 
  • Like
Likes: ggrizzard
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Scott. This is where you need to find a person that is small, wiry and not claustrophobic.
I’m reminded of the lady working upside down on a motor with only her ankles showing from the lazerett @capta posted a couple of years ago.

It would be worth hiring someone for a day.
Or you could try and install an inspection plate. Beckson Marine makes some water proof ones.
1580257665567.jpeg


that can give you access to inaccessible places.
 

Mr Fox

.
Aug 31, 2017
204
Marshall 22 Portland, ME
Sorry if im repeating what you already know- If the flange and screws are stainless it looks like you need to rebed that flange and the screws, water is getting in. Remember stainless will rust if not exposed to oxygen; so poor seal, water gets in, no air and that makes rust that bleeds out around the screws. I'd follow TomY's advice. Good luck let us know how it turns out.