Can anyone provide a primer on how to run one's diesel motor in order to increase the life of the mixing elbow? What makes it corrode more quickly and how does one avoid it? I have a 2QM15.
Increase the Mixing Elbow life?
- Thread starter Stephen Trapani
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I always wondered if a coating of silicone or a dip in a real good quality rust proof paint would help in the longevity of the elbow. If an elbow could be made of pure silicone it would last forever if it could be made to stand the pressure. Any thoughts ?
Maybe a ceramic coating, but it is probably cheaper to just buy one and have it on hand when it's time.
The elbow itself is NOT that expensive as long as you don't need to replace the manifold & coupling.
The elbow itself is NOT that expensive as long as you don't need to replace the manifold & coupling.
There are designs that are prone to fail sooner that others. The ones with lots of small water holes around the perimeter tend to fail sooner as it is easier to get carbon formations to plug a small opening. Your best bet is to:
Not idle the motor excessively (charging the bats at anchor, at the slip warming up)
Not "lug" the engine with too much prop
Keep the bottom clean to reduce drag to design levels
Choose an elbow that has one large water hole
I've not found that running the engine at reduced throttle has any effect on carbon build up and don't recommend "blowing out" the engine with WOT runs. If you see soot in the exhaust or on the water you are doing something wrong and need to fix it as soot is what cloggs the elbow.
Not idle the motor excessively (charging the bats at anchor, at the slip warming up)
Not "lug" the engine with too much prop
Keep the bottom clean to reduce drag to design levels
Choose an elbow that has one large water hole
I've not found that running the engine at reduced throttle has any effect on carbon build up and don't recommend "blowing out" the engine with WOT runs. If you see soot in the exhaust or on the water you are doing something wrong and need to fix it as soot is what cloggs the elbow.
All - do you think salt is a major contributor to pre-mature failure here?
I'm not sure if it is or not as I'm not an expert here - it sure does wreak havoc on everything else. On my raw-water cooled engine, I rigged a simple fresh-water flush system that pumps fresh-water throughout my engine and exhaust system; I run the fresh-water flow for about 5-7 minutes before final shut-down.
I have a custom exhaust riser on my YSM12. The elbow did fail on me recently but I believe it was approaching its useful life regardless - so I thought (~15-17 yrs old). The shop that built the riser and then did the repair told me it gave-way due to vibration and that I need to install a support bracket on the riser bolted to the engine/transmission when I re-install. Anyway, he said the complete riser was in terrific shape with little to no corrosion and the only think I needed to do was weld in a new SS section that was about 6 inches long (the infamous elbow section that bolts to the engine manifold).
I'm not sure if the fresh-water treatments help but it sure doesn't hurt. Even if you have a fresh-water cooled engine, you have salt water in the riser and exhaust systems at all times and this may contribute to corrosion, especially with the high heat.
- Rob
I'm not sure if it is or not as I'm not an expert here - it sure does wreak havoc on everything else. On my raw-water cooled engine, I rigged a simple fresh-water flush system that pumps fresh-water throughout my engine and exhaust system; I run the fresh-water flow for about 5-7 minutes before final shut-down.
I have a custom exhaust riser on my YSM12. The elbow did fail on me recently but I believe it was approaching its useful life regardless - so I thought (~15-17 yrs old). The shop that built the riser and then did the repair told me it gave-way due to vibration and that I need to install a support bracket on the riser bolted to the engine/transmission when I re-install. Anyway, he said the complete riser was in terrific shape with little to no corrosion and the only think I needed to do was weld in a new SS section that was about 6 inches long (the infamous elbow section that bolts to the engine manifold).
I'm not sure if the fresh-water treatments help but it sure doesn't hurt. Even if you have a fresh-water cooled engine, you have salt water in the riser and exhaust systems at all times and this may contribute to corrosion, especially with the high heat.
- Rob
Someone, maybe Blaise over on the Cherubini forum, had an elbow made from stainless. If I remember correctly that elbow does not corrode and close up.
What is the expected life of the elbow? My 1986 Catalina 30 with a Universal XP 25 still has the original elbow and the boat is run almost everyday on the weekends.
It don't think how you run the engine makes a bit of difference on how long it will last. I think it depends on the type of metal it is made of, plus how much moisture is always in contact with it, and how well the engine is grounded.
It don't think how you run the engine makes a bit of difference on how long it will last. I think it depends on the type of metal it is made of, plus how much moisture is always in contact with it, and how well the engine is grounded.
Rob:
I think it is a combination of the exhaust and the salt water. When I checked mine on our H'31 after 7-8 years it was still in good condition. I replaced it because I had purchased a new one (anticipation) so I replaced the old one anyway.
PS: Our boat lives in a fresh water environment and only sees salt about 2-4 times a year.
Carbon build up = corrosion?
So are you saying the soot speeds corrosion? And you're going against the conventional wisdom that idling or low RPMs increases soot? Sorry, I'm confused.
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