Catalina 350 International Association

After all the discussions about blown engines, etc., I decided to replace our exhaust riser. Boat has been in salt water 13.5 years with 1800 hours on the M-35B engine. I purchased the Westerbeke part number 037403 from Discount Marine for $234. Part number cast on the riser is 36743. Apparently the 037403 is a new part number, but the new part came in with the same old 36743 still cast on both sides of it, however it was Westerbeke fire engine RED. I painted it silver to match the engine. Discount Marine also sells the Universal Exhaust Riser 200490 for $260. Close inspection of the photos of that part number show "Westerbeke 36743" cast on its side. Here are a couple pictures of what the inside of the riser looked like.

I had to cut off a piece of the section where the exhaust hose connects to create enough 'throat' in my hacksaw to cut the interior walls. As you can see there was no significant wear or erosion. The walls are quite thick and the only wall where salt water could possibly get in the engine is the wall separating the raw water from the exhaust path between where the water enters and the top of the top of the elbow.
This is a blow up of the greatest erosion I found. You can see that the wall just below where the raw water enters is about 1/2 the thickness that it is everywhere else. This makes sense as this is the area where raw water would accumulate until it evaporates. After 1800 hours, I feel this is pretty minimal erosion, but I will sleep better knowing that it has been replaced.

I want to replace mine as well, but I can't find a replacement part that looks like that one. Here is a photo of mine, but the replacement doesn't have that plug on the top. I know the ads say there have been mods on the engines and maybe this is ok.

Any comments?
thanks

dave

Hi Dave,

I bought mine from here; https://discountmarinesource.com/store/ ... UNV-200490 and replaced it this past summer. Easy job.

As to your question, the plug on top is not needed.

Bill
Atlanta, GA
#193

You can also purchase westerbeke part 037403 from Discount Marine Source. It is exactly the same part except it is painted fire engine red and is less expensive (about $237). The riser comes with three brass fittings including the plug in the top, the larger plug in the side of the riser that is not used, and an elbow fitting for connecting the raw water hose to the side of the riser which is used. The riser also comes with a round gasket and clamp for attaching to the exhaust manifold flange.