Another Elbow Question

[MikeHoncho]

Took the boat out yesterday for some new equipment shake down (radar, autopilot) and realized there was no water coming out of the exhaust. I have a “pee” set up on my boat that shoots raw water out the stearn to show the pump is working properly. I check this repeatedly and it was flowing strong so I know the engine was getting water but the exhaust was not.
Idled back to the slip and got into my manual. I found a clogged elbow that feeds raw water to the elbow from the HE. Problem fixed in 2 minutes. Back out for the shake down with no further issues.
Now my question. I want to remove the elbow for inspection. It is a inverses U type with typical difficult access. It appears to be more appropriate to remove the elbow at the 4 bolt mounting surface that attaches to the exhaust manifold than trying to get pipe wrenches in there. How common is it to be able to reuse the gasket? Is it a typical steel type exhaust gasket or a one and done type one? Opinion?

 

[Ralph Johnstone]

The gasket is a once only grafoil type and runs about $18.00 CAN. Even at 10X the price, this is the last gasket you want to leak. A word of advice ............ the replacement of the gasket is the mother of all creation. Came upon the idea of using guides to replace the gasket and riser flange some years back:



Make sure you use LOOAAAAAAADDDS of parting compound on the gasket and flanges when you reassemble. You'll see why once you get into it. Grafoil gaskets break apart nicely but are bears to clean off.

This is what you'll probably be looking at once you get into it:



Also, watch the threads on the riser joint CW and CCW.

 

[MikeHoncho]

The gasket is a once only grafoil type and runs about $18.00 CAN. Even at 10X the price, this is the last gasket you want to leak. A word of advice ............ the replacement of the gasket is the mother of all creation. Came upon the idea of using guides to replace the gasket and riser flange some years back:

View attachment 187279

Make sure you use LOOAAAAAAADDDS of parting compound on the gasket and flanges when you reassemble. You'll see why once you get into it. Grafoil gaskets break apart nicely but are bears to clean off.

This is what you'll probably be looking at once you get into it:

View attachment 187280

Also, watch the threads on the riser joint CW and CCW.

View attachment 187281

Noted on the gasket lol. I saw that pictures of it cut in half. I don’t think my elbow is original and think I will try to soak it in something to break up the restrictions prior to replacing if needed.

 

[Ralph Johnstone]

The grafoil gasket on the removed flange will come off nicely, with a razor sharp wood file, while sitting in your lap. It's soft but sticks like crazy to the flange. The murderous one is the one attached to the engine. Have a loved and trusted one hang you upside down, by your feet, over the engine and see if you have any luck cleaning it off.

I check mine every 2 - 3 years, hence all the cautions !

 

[MikeHoncho]

I think I might remove the exhaust hose and use my endoscope to take a look/see in the water channel before removing. I’m considering trying to ream it out in place. Exhaust components and I don’t historically get along.

 

[Ralph Johnstone]

Exhaust components and I don’t historically get along.

I think it's a common experience with everyone !

As far as reaming it out in place, can't offer too much encouragement there. The carbon inside the hot gas passage is in the process of turning into diamond it's so hard. You may have some luck with the cast iron corrosion products but don't hold your breath.

I think when you finally pull yourself out of the rear of the engine, you'll say the hell with it, pull out the entire assembly, unscrew the elbow and invest in a new one.

This invoice is for a mixing elbow back in 2012:



Today's price is anyone's guess.