Exhaust Hose Rubber Lined??

[Sidclark]

I was washing the boat today to get ready for haulout for bottom paint and I'm on the swim platform when I looked down at the exhaust exit and saw this stuff protruding from the exit. It was black rubber, inner tube like, material. I grabbed ahold of it and was able to pull out about four foot of it. Question is, the exhaust hose may be original, so were the 1985 vintage hoses rubber lined? I've never seen this happen before so it's a little odd. Anyway, looks like new exhaust hose and bottom paint. I did run the engine and the water flow and exhaust flow looked good. I'll keep an eye on it as it's a 26 mile run to the yard.

36 Marine Trader with a 135 FL...

 

[firehoser75]

Sid,
Sorry to hear of your exhaust hose issue. They are a maintenance item, and if it is 35 years old, I would guess way past due. I have seen those hoses delaminate, usually from overheating.
Quick story. When I first got our boat, I installed an exhaust temperature overheat alarm (Borel) on the hose just after the shower head where the water is injected. The next summer, that alarm kept sounding. I had 2 different mechanics have a look at it to determine why the hose was overheating (I confirmed it with an IR gun). Neither one was sure, and their guesses were (to me) all over the map. I was sure that it had to be the exhaust elbow, as all other engine temps were well within spec. Turns out I was right, my elbow had corroded through in a few spots on the inside and it was not visible at all. Glad I installed that alarm, as if this issue had gone on, I could have "sucked" water into my turbo or even the exhaust manifold. I also caught the issue before the hose suffered any visual damage. My hose was rated for 200 degrees F, and I was seeing spots of 220 degrees.
I would guess that your hose problem could be just "old age", but I suggest you check out your cooling system, especially your exhaust elbow to ensure no issues there. By the way, my elbow did not show any problem visually until I took it to the radiator shop for a good cleaning. Then the holes (very small) were visible. Even the "shower spray" looked good when I used the garden hose to supply the water on the dock. It needs to be cleaned to be sure.
I am not an expert on this, but this is my experience.

Good luck.

 

[Sidclark]

An update. Started out this morning to take the boat 26 miles for the haul out. Ran about 1400 RPM for a mile while tiding up dock lines then ran her up to 1800 RPM and watched the temp start to climb. She got up to 200 degrees so I backed off to 1200 and limped back to the dock as the temp came back down. So, I figure too much backpressure because of whatever rubber is still inside the hose caused the temp rise.

So, plan B is playing it safe and have Sea Tow take her upriver to the Haul out where I'll replace all the exhaust hose.

 

[Steve1.0]

This is what the inside of my 8" 1992 exhaust hose looked like.

 

[Steve1.0]

Here is my replacement.

 

[Sidclark]

Here is my replacement.

That's what my run looks like. Pretty easy access and a straight run. I believe I have either 3-1/2 or 4 inch line. I'm glad this happened before we left for Florida!