Servicing our Exhaust Muffler

Servicing the Exhaust Muffler on our Catalina 34

In July 2016, our Aqualift Muffler had an issue and I serviced it (Here's the link), at that time, I repaired cracks that had formed between the Muffler body and the Inlet & Outlet tubes using a 2 part Marine Epoxy.

Well, I thought those cracks had reappeared, so I pulled the Muffler out to bring it home and inspect then repair.

I released the hose clamps from both the Hump tube and the Exhaust pipe and then gave the hump & the hose a sharp twist to break their hold on the tubes.

There's barely room to pull the hoses off of the muffler - I think that is due to the fact that when I last did this repair, I added a 1" piece of ply beneath the Muffler as the new Exhaust Riser reached further to Port, the 1" made all the difference.

With the hoses off, next I released the 4 screws that held that Muffler to the new piece of ply.

Struggling to get the Muffler out from the area beneath the aft berth, I was able to move the muffler out of the way of the screws that held the new piece of ply to the original and then slide that new piece out of the way. Then I was able to slide the Muffler aft and towards the center. I did touch the PSS ( shaft seal ) so some water came it, not much.

This shows the original ply base for the Muffler. the dark patch is probably from the Diesel leak we had last year. I'll clean up all that area before putting the serviced muffler back in place.

I added that ply back in 2016 and will replace it with a 3/8" ply base. That should mean that it will be easy to replace the muffler.

The new piece of ply will be fully sealed with epoxy before that gets installed over the top of the original ply.

With the Muffler out, I brought it home to service it.

Servicing the Muffler

Step 1: Wash it down with soap and water. I'm pretty sure the leak was from the Inlet side of the muffler but not where expected. Now I'm pretty sure it's from the Malformed Inlet Tube, it looks like it has a fold along the length of the tube, one that cannot be closed by just using hose clamps on the hose.

Step 2: I dried of the outside of the muffler and filled it with water, all the way to the brim of the inlet and outlet tubes. NO WATER LEAKED!

Step 3: Using a Dremel, I cleaned up the fold in the tube so that I could fill that fold and thus ensure that the hose clamp can fully close the Hump Hose around that tube. Then I sanded down the entire surface with 60 Grit paper, and use the Dremel to remove any lumps in the surface of the tubes. I did the same for the area around the drain tap.

Step 4: After the sanding, I washed the entire surface with Acetone, got out some Marine 2 part epoxy and filled all of the dings that needed it. Then let the Epoxy cure overnight.

Step 5: Second wash down with Acetone and time to paint the entire surface of the Muffler. ( A new one cost around $700 ). I am applying 2 or 3 coats of the Petite EZ-Poxy Modern Polyurethane Topside Paint, Med White, same as what I used on the Propane Cylinder holders last year.

This is after the crack repairs, sanding and the first coat of paint.

Looking good. Should be really easy to keep it clean. 

Another coat this evening after a light sanding with 600 grit paper.

Using this paint is really a pleasure.

Not sure I'll need a 3rd coat.

Hoping to go to the boat in the morning to do the clean up of the under sink area and re-install the Muffler.

I decided on flipping the Muffler upside down and applying a coat of the epoxy paint to the underside and adding a 3rd coat around the outside of the base, just to complete the job.

I'm really not sure why the lower edge is 'shaped' as can be seen here on the far right surface of the edge.

The Muffler was originally installed onto a piece of ply just about the same size as the outside edge of the muffler, it's FLAT, so why that weird cut on the underside of that edge.

The Drain plug is missing from this image as I removed it before starting the refinish process.

The drain plug is showing it's age, but is still functional. So I spent a few minutes cleaning it up with a handheld wire brush and a piece of 600 grit paper. Scrapped off some of the heavy build up and removed as much of the old Teflon tape as quickly possible.

It looks like a tapered thread but I'll still add several wraps of tape.

Finally washed it down with some Acetone and put it back in place in the Muffler.

Turned out pretty good. 

I really wish that the area beneath the head sink was as nice as the refinished Muffler. But I'm not going to spend much time cleaning it up. 

It will have to just enjoy the soap and water wash down and a bit of scrubbing before I reinstall the Muffler.

Current Schedule is to install it on Friday. Hopefully is not still freezing down here. I know it's SoFla but... Dang! it's been as low as 29ºF this week.  That's too cold to go up the mast to work on the standing rigging, but not too cold to work in the cabin.

Ok, install complete ( bar the shouting ) just need to screw the muffler to the base but my right angled cordless screwdriver battery was flat and spare was at home grrrrr.

It took a bit of maneuvering, but I got it done.

We ran the engine and a small leak showed that the hoses, both input and output were not quite tight enough. It only took a few minutes to fix that. But then we found ( ok, Peggy found ) water dripping from the Anti Siphon valve in the hose that leads from the heat exchanger to the exhaust riser nipple.

I removed the valve cover and the birds beak valve, all looked good and clean, it's not that old. So put it back and tightened the cap and the two hose fittings. Ran the engine again, this time for about 10 minutes while my leak sleuth checked everything again and it all looks good.  Plenty of water gushing from the exhaust. 

Cross this one off the list once I screw down the muffler, that should only take a few minutes than I can put the Aft Berth back together. Oh, refit the door too.

See you on the water --- soon!

Paul