Main Diesel Engines - When to replace Exhaust Hose?

[sgharford]

The only rubber I have not replaced since I bought my 1976 43DC with Cummins Turbo 903's with about 1800 hours on them is the 6" (or so) diameter exhaust hose from the shower head to muffler to fiberglass tube going out the transom. Sure looks like a huge PIA and I'm second guessing if I should do this just for the sake of doing it. For all's I know the existing hose is original. I imagine any damage to hose would be from inside and therefore only way you know if bad is by removing it.

Is there any 'test' you can do to see if exhaust hose needs replacing without actually removing it?

[rsmith]

40 year old rubber hose is going to be rock hard and can split or crack. Mine are 12" and a few years ago I started getting a coating of salt spray on everything under the back deck. Turned out there was a tiny split in the hose.

[sgharford]

Yep - exactly what I don't want. Thinking this is year for my big '2 week trip' on her with family (been a pipe dream for seven years, in my defense I keep procreating and baby's are no fun on extended boat trips). Seems like prudent preventive maintenance item, but man is that space tight. You know how your muscles tense up when it's 20 degrees out and you are squeezing into tight spaces, using muscles you haven't used in years, alone, in a deserted boat yard? I already know answer to my question, but I have to ask.

[saltshaker]

If in doubt change them. You've owned the boat long enough to warrant a change. Do you have longer hose runs or are these small pieces that couple the FRP tubes to the mufflers? The piece from the engine to the muffler should be straight forward. The ones from the muffler to the pipes or transom may be a bit of a job. If they just couple the muffler pipes and thru hull flange they may be OK. If there's any length to them I'd replace them. Make sure the mufflers are supported either from straps above or sitting on a cradle. There's a lot of weight there when they're filled with water. That's when the hose connection will fail. FYI my '74 46C had all original exhaust when I repowered in 2002. All was in good shape except for one broken hanger. I had to cut the aft bulkhead to get to the mufflers.

[MikeP]

40 year old rubber hose is going to be rock hard and can split or crack. Mine are 12" and a few years ago I started getting a coating of salt spray on everything under the back deck. Turned out there was a tiny split in the hose.

That's why they make duck tape!


Seriously…I wouldn't personally replace a hose that didn't appear in need of replacing. You can observe/poke/feel around and, IMO, determine if the hose needs replacing. OTOH, it's hard to argue against replacing all old hoses. So my answer is: Do whatever you think is best!

But since you are going to be making a long trip and are asking the question, I suspect you'd be more comfortable with new hose.

[Cricket]

Replace it with silicone hose, it will be much easier to work with than trying to get the rubber stuff back on.

[sgharford]

Outside of rsmith, whom I've gathered from past posts has many nautical miles under his hull, has anyone else ever had an exhaust hose give way on their main engines? Thanks for feedback on your hose Jack, and Mike your opinion is always well valued. Cricket - appreciate advice on silicon hose as getting them back on in tight spaces is one of big concerns. I really don't want to do this project, but that's not reason enough.

[Finalee]

Yep I had several failures. Once on a sailboat, the other on a Carver with twin 302's. Each time it was an internal failure that eventually resulted in the exhaust hose coming apart. Had to shut down the engines or sink the boat. This is actually on my to do list for the spring.

[jim rosenthal]

I have not had an exhaust hose fail, but I HAVE found engine seawater intake hoses that were VERY close to failure- and not that old! And they have an easier life than seawater exhaust hose. So, yeah, even though it's going to be a huge pain in the butt, they ought to be at the least very thoroughly inspected, and I suspect you'll find some that need replacing.

The silicon hose IS much better. It costs a lot, but it's worth it for the peace of mind. It comes in three temp ranges, and most of us use the blue one, which is the lowest, I think, but all you need.

And, FWIW, we used Vetus seawater intake hose when we did those. I think it is better than the competition, like Trident or Shields. The seawater hoses that were about to fail were Trident- they were disintegrating.

[Boatsb]

I've replaced more than a few that were cooked from loosing seawater. After restoring water they almost sank when the exhaust hose failed. If they are accessible change them. If they are not check them any way you can because they carry a lot of water and rushing back to shore when one breaks is not an option.