Exhaust…take care.

[jandane]

During engine maintenance I discovered small specks of rust/water on the exhaust knee. It was made of stainless steel. I took it off, installed a new and when home, I polished it and discovered a very small crack on the lower side plus a tiny rusty wound on the upside..
I placed a screwdriver on the wounds and after ONE beat with a hammer, the screwdriver went through both the rusty speck and the crack. The knee split in two and I saw, that the welding was rusted up from inside. Thanks I saw it now and not at the sea during summer’s sailing.
Lesson learnt: Check the exhaust pipe every year.

[Brian & Glenda]

Wow! Thanks for the advice. This is something I'll have to pay special attention to next time I'm at the boat. Along with a visual check, I wonder if a cracked still installed unit would yield an identifiably different sound when tapped with a hammer, as compared to a non cracked one.

How old do you think the failed component might be? I don't know whether engine hours or age might be a better measure of this component's life expectancy.

I'd bet that very few boaters have a new one on hand, as it seems you did! You must have been a Scout ... Be Prepared!

Brian.

[jandane]

Brian, I do not know the age of it. When it came out, my idea was to polish it and keep it as reserve, but when polishing, I noted a very fine rusty line on the lower side. Tapping with a hammer gave no significant response. A friend of mine, expert in welding stainless steel, could tell me, that the reason was it has been welded in a wrongly manner, not using gas on the inside….whatever that might mean. Today I am a sworn supporter of the original cast iron knees, meant to be changed every 5-6 years

[phil0110]

Thanks for the good advice! I'll check it