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When the exhaust system fails, it's time to...

Overhaul the exhaust system

It was a nice day of sailing last January when we heard the smoke alarm go off and I went to investigate and noticed smoke/steam coming up from the engine compartment. The engine compartment has an automatic extinguisher system and it was not going off. I noticed steam and smoke coming from the engine cover; the engine was shut down as we glided into the slip. Perfect conditions and timing for a thing like this to happen. I pulled the engine cover and saw water and soot all over everything and then I saw the elbow and hose knew what the problem was. The exhaust riser was failing. Fortunately we were on our way back to the slip.

The first couple of pictures show how it had failed. The collapsed hose going into lift muffler and the mixing elbow weld breaking.

I had to remove the shelf in the aft cabin and it had never been removed before. It was screwed together from the inside so that was the first challenge. It took a lot of contortions to get one side of the shelf off, but it was enough for me to work on the exhaust and heat exchanger.

RalphJohnson_CollapsedHose.jpg (1018912 bytes)

The collapsed hose

RalphJohnson_ExhaustElbow.jpg (893879 bytes)

You can see the exhaust elbow

I found that when I went to remove the exhaust riser, the flange screws were rusted to the exhaust flange, so I had to cut off one of the nuts.

RalphJohnson_Flange.jpg (978421 bytes)

The flange is removed

The stud was stuck in the exhaust manifold and it took weeks of soaking with PB Blaster and a pipe wrench to finally remove the stud.

RalphJohnson_RiserandHeatExchanger.jpg (735574 bytes)

The riser and heat exchanger, removed

RalphJohnson_InsideHeatExhange.jpg (630186 bytes)

The inside of the heat exchanger

I soaked the heat exchanger in CLR for a couple of days and the used a small stream nozzle on the water hose and it cleaned up very nice. I replace the zinc and put on new end caps and gaskets.

RalphJohnson_Systempieces.jpg (904636 bytes)

The pieces of the exhaust system, removed

I replaced all of the cooling system hoses on the engine as well as the hose clamps.

Parts:
     - I ordered a new exhaust riser from Catalina
     - A new exhaust flange, studs and gaskets
     - A "hump hose"
     - And a new zinc, end caps and gaskets for the heat exchanger

RalphJohnson_OldandNew.jpg (995670 bytes)

The old pieces, and the new

The riser from Catalina was well made and well insulated. When I went to dry fit the riser on the exhaust manifold, the riser would not mate up with the muffler. I had to remove the insulation to get to the SS threaded elbow. I used the vise in the marina shop and a big pipe wrench to twist the riser in two directions to get it to line up with the muffler. This did the trick and I was able to get it to mate up with the muffler.

You will notice in the after picture that there is a not a hump hose going to the muffler. As the saying goes… Measure twice, cut once. When I was dry fitting the hump hose and riser, the riser slipped off the stud and I didn’t notice when I took the measurement. Needless to say, it was easier to buy a hose from the marina than wait a week for a new hump hose.

The photos below show the new exhaust system put back in place...

RalphJohnson_Installed1.jpg (962157 bytes)

RalphJohnson_Installed2.jpg (858693 bytes)

RalphJohnson_Installed 3.jpg (515568 bytes)

I filled up with 50/50 antifreeze and fired her up. No leaks. We’re back in business.

Thanks to all of the c36 maillist participants who helped me with this project with all of the advice and encouragement.

Ralph Johnson
Still a Thrill #765
Lake Texoma, TX