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Old 09-06-2010, 17:36   #1
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Cleaning Exhaust Manifold / Mixing Elbow

The water inlet on the mixing elbow of my 3GMD is totally blocked. When I removed the elbow I found the exhaust manifold outlet is ~ 40% blocked with carbon.
Question: Should I use mauratic acid to remove the carbon buildup from the manifold and elbow?
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Old 09-06-2010, 17:44   #2
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It will be a sort lived fix, I would recommend a new elbow as they should be treated as a 'wear' item and replaced every 3 to 5 years. It wil.l be cheaper than a new engine, which is potentially what could happen if the elbow fails and allow water back into the engine.
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Old 09-06-2010, 17:48   #3
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Exhaust Mixing Elbow Inspections

Might want to read the linked thread and severl others that you will find listed at the bottom of this thread.
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Old 09-06-2010, 18:00   #4
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This has been discussed ad nauseaum on other threads. In salt water these elbows last 3-5 years. Replace the elbow/special nut.
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Old 09-06-2010, 18:03   #5
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The elbow isn't damage that I can tell. There is just a lot of carbon build up. Plus the sediment from my water heater that blocked the water intake. I have pictures, but I don't know how to add them to my post.
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Old 09-06-2010, 18:07   #6
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I forgot to say I'm in fresh water.
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Old 10-06-2010, 04:11   #7
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You'll be the 11ty billionth person who cleans, then later replaces the elbow. The parts are not expensive just replace them
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Old 10-06-2010, 05:02   #8
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Job knowledge for welders 25: Weldability of materials - cast irons
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Old 10-06-2010, 22:18   #9
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A quick clean-out can be done by putting several layers of masking tape over the external threads to protect them and then take the elbow to a local "sand blaster" and have them blast out the inside of the elbow. Then measure the thickness of the walls of the unit. You will probably find them quite thin when compared to a new elbow. Normal experience is that after spending a lot of time cleaning and inspecting you end up replacing the unit - so why bother doing all the cleaning?
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Old 11-06-2010, 06:41   #10
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Old 14-07-2010, 03:55   #11
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Quote:
Originally Posted by Duke 48 View Post
I forgot to say I'm in fresh water.
Have you replaced them?
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Old 14-07-2010, 04:16   #12
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Muriatic acid does not dissolve carbon. Sandblasting, wire brush, careful cleaning followed by buying a new one is the best route
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