[C320-list] Mixing elbow failure

[Donald Lawson]

All
Same problem, many symptoms.
I resolved my no increase is speed under load above 2200 rpm as a carbon plugged exhaust riser/mixing elbow on my 3YM30.  Chipped out the carbon and everything works fine but I am going to replace it anyway. The less backpressure the better.
I think I caught mine in time.  I am going to replace mine every 3-4 years as part of my maintainance program. Small price to pay then have to go through what Jeff is going through.
I just got back from a trip south from Ventura, CA with a Cat 36.  He could not go faster than 2500 rpm without overheating but he went anyway. He has a Universal with a Stainless mixing elbow.  It has a large crack just before the water entry and the same carbon buildup in the exhaust side.  Stress/Crevice corrosion?  Cost to replace is unkown but is expected to be expensive.  Mechanic is going to build him a cheap set up using cast iron pipe and he is going to replace it every 3-4 years.
Don Lawson
Mandolin Wind.  
On Aug 18, 2015, at 12:11 PM, Doug Treff wrote:

> 
> 
> All, 
> 
> Just a follow-up on this matter. My marina manager advised me to contact
> my insurer (Boat / US) and they had a surveyor out there today to
> inspect the damage before repairs or clean-up were attempted. 
> 
> What actually failed was not the mixing elbow. The threaded section of
> exhaust between the manifold and the elbow snapped. But it was
> apparently leaking beforehand and that is what caused the sooty mess.
> They did find seawater in my cylinders and they removed that and sprayed
> some oil in the cylinders and worked the engine manually to prevent
> corrosion until repairs can be made. My exhaust system from the engine
> to the muffler will need to be replaced, along with an oil change and a
> clean air filter element since the old one was all sooted up. The
> surveyor said he's never seen one fail like this before. 
> 
> Most likely the soot clean-up will be done professionally for only the
> cost of my deductible. I will only have to pay for the engine repairs.
> As my deductible is only $137, it's worth it to me to have it
> professionally cleaned. My yard does great work and I'm sure it will be
> cleaner than I could ever manage. 
> 
> Have any of you out there gone with the stainless mixing elbow instead
> of the cast iron, and how do you like it? 
> 
> ---
> Doug Treff
> Catalina 320 - 1996 - September Song - #350
> http://savvysailor.blogspot.com/
> doug at treff.us
> 
> On 2015-08-18 10:58, jim brown wrote: 
> 
>> Simple Green might work OK. If not I swear by Zep Heavy Duty Citrus Degreaser from Home Depot for those times when the regular stuff doesn't cut it. It really does remove grease, oil, exhaust soot very well. 
>> 
>> Jim Brown
>> 
>> From: Doug Treff <doug at treff.us>
>> To: C320 List <c320-list at lists.catalina320.com> 
>> Sent: Tuesday, August 18, 2015 9:49 AM
>> Subject: [C320-list] Mixing elbow failure
>> 
>> All, 
>> 
>> I had the misfortune of suffering a failure of the mixing elbow this
>> weekend. Apparently it partially clogged and exhaust was leaking into
>> the engine compartment. Fortunately I was able to run it very gently
>> back to the slip by keeping the RPMS low. The engine temp never went
>> over 180 and I continued to have a strong amount of water coming out of
>> the exhaust port on the hull. 
>> 
>> I have a mechanic looking at it this week to give me the official
>> diagnosis but based on what I could see, it was the mixing elbow. I just
>> hope that the head gasket wasn't blown due to excessive back pressure. 
>> 
>> Unfortunately now my entire engine compartment is covered in a layer of
>> soot. I am thinking Simple Green might clean it but I am open to
>> suggestions if you have any. Wiping down the entire engine and all of
>> its nooks and crannies sounds like a time consuming and nasty job.
>