Replacing exhaust hose

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Chris Foster

Senior Member
Oct 12, 2007
Vessel Name
Vessel Make
46 Grand Banks Classic
Looks like I need to replace about a 4 foot long piece of 4 1/2" exhaust hose that runs from the stbd engine outlet to a fiberglass elbow that sends it aft.* There's a 90 degree bend in the middle.

Any hints on doing this?* I assume the odds are pretty good that I'll have to hacksaw the old hose to release it enough to get it off.* Or is this one of those "best hundred bucks I ever spent was getting a guy from the yard to come down and muscle the SOB into position" situations??
As far as getting it off.....what I have always done is get a flathead screwdriver and wedge it as far in there as possible and whithe tool still inserted pull material aways and spray penetrant(my favorite being Boeshield) in the space you have created. DO this all around the hose and then crack a beer. By the time you have finished your beer, she will likely slide right off. If it is melted on, then I dunno......

-- Edited by Baker at 09:46, 2008-10-27
I replaced a section of my exhaust hose last spring and found the fiberglass muffler end came off easily. The cast iron engine end was more difficult, but with the leverage of the length of hose I was able to wobble it off fairly easily.

I also found that the local hydraulic hose supply house had the exhaust hose for 1/4 the price of the "marine" folks or the auto parts house. It's worth a phone call at least.

You might want to get what I call a "Sneaky Pete" (cotter pin tool). It resembles a long awl, bent to 90 degrees on the end. You can slip the point under the hose and pull it around to dislodge the hose. Recently I changed a long section of black water hose and cut it into sections with my SawzAll with a fine tooth blade.This made for much easier diposal and also helped to get the ends loose. If you used this method you would probably need a 6" blade for the larger diameter hose.
The right tool makes all the difference. What you want is called a "hose pick". I use the one with the bent end (Stock #: SGA175BR) so I can pull around the mount. See:

It is worth it to find (or make) yourself one of these. Another trick is to put a little silicone caulk (high temp black for exhaust) on the fitting before sliding the new hose on. This will not only help it slide on, but slide off again years later. A little regular clear silicone caulk does the same for regular water hoses. The PO did this on my boat, and it was amazing how easily everything came off after years of use.

-- Edited by Keith at 06:46, 2008-10-28
I also found that the local hydraulic hose supply house had the exhaust hose for 1/4 the price of the "marine" folks or the auto parts house. It's worth a phone call at least.

Marine exhaust hose will have markings on it that proves to the hooligan navy (USCG) and to your insurer it is usefull as exhaust hose.
The hose pick was a really good call.* The local NAPA store had one for a whopping $4.95 that I abused the s__t out of until it finally gave up.* It had the pick end bent into kind of a square "U", so it wouldn't go as far between the hose & fitting, but gave a good tool for pulling the hose.

(Warning:* rest of this post contains a lot of whining)*

As to the job itself, well, my lifelong fantasies of becoming a professional marine exhaust maintenance person have been dashed.* Even with the tool, I still had to hacksaw through pretty much all of the hose to get it to release (it had about 6" of overlap on either end.* The old hose must have been in there for quite a while - it was 4" corrugated, and pretty much disintegrated in the area of the tightest bend when I pulled it out.* Access to the line was via "assuming the position" of crawling around the outboard side of the stb'd engine.

Since I had to move the boat on Friday (yesterday), I made certain that North Harbor Diesel had 4" exhaust line in stock.* No problem, they said.* So I pulled the old line out and went to get 3 feet of new.* Oh, we don't stock corrugated line.* Ooops.

Since I had to make a 90 degree bend in less than 3 feet of line, using standard exhaust line alone was out of the question.* So I bought a fiberglass 90 plus 3 feet of the standard stuff.

The problem now was that, while everything would fit beautifully once in place, there was too much misalignment to get everything to start.* Slashed the heck out of my hands trying to muscle it into place as my hand would inevitably slip and rip across the (sharp) wire at the end of the hose.

The silicon sealant was a also good call as there's no way that I could have slipped the line over the ends without it as a lubricant.* Unfortunately, within 10-15 minutes, it would start to cure to the point that things wouldn't move at all.* So during the 3 or 4 different attempts at trying to get it to go together, I had to pull everything apart a few times and scrape the curing sealant off.* I'm wondering if something like Dow/Corning # 4 (DC-4) wouldn't work better - it's basically a high temp silicon grease that doesn't hurt rubber, neoprene, silicon rubber, etc.

The final solution was to reduce the amount of hose overlap on the water/exhaust injector (don't know what to call it - it's not a "riser" as the turbo outlet is well above the waterline - this is just about 10" long, bolts to the turbo on one end, has a water hose coming in on the side, and has the exhaust hose on the other end).* You can overlap the exhaust hose by over six inches, but the bead is at the* very end of the fitting... so I decided that about 3" of overlap would be adequate (allows two clamps above the bead).* My final trick was to put one piece of hose all the way up the injector, then install the other piece of hose and the fiberglass elbow, and then slide about 3" of hose down the injector over the elbow.

The installation saga ended about 3 hours after it started.* But it doesn't leak water or exhaust.* And I managed to get moved to my new slip yesterday morning before the wind picked up!!
Glad to hear the job was successful! I am sure 3" will be sufficient. Check that one off the list.
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