Bob,
I removed the whole assembly. The main passage of the "U" shaped piece (mix
elbow) was clear.
Here's the whole deal. First I cranked the engine to verify no water
discharge. Then I pulled the manifold water hose from small elbow. Seeing
flow there, I knew the pump, heat exchanger, manifold, etc. were OK and the
blockage was in the mix elbow somewhere.
First I removed the exhaust hose from thedischarge of the elbow. Then I
removed the throttle cable (8 mm head) being sure to not let the clamp assembly
and threaded back plate not fall under the engine.
Next I removed the 2 bolts (12 mm) from the exhaust transition piece. Then I
removed the 2 nuts (13mm) from the studs passing through the exhaust transition
piece. A slight tap with a dead blow or rubber mallet will loosen the exhaust
elbow assembly. I took the assembly to the dock, removed the small water
elbow, cleaned it and the "cup" inside the upsweep passage of the mix elbow.
By "cup" I mean there is a baffle just inside the mix elbow where the water
elbow screws in. It faces upward in the upsweep side of the mix elbow. So the
raw water discharge from the manifold enters this cup and overflows into the
upsweeping exhaust gases. I'm guessing that when the engine is shut down, this
cup may retain water. That may be a part of the problem.
To re-install, I reversed the procedure with the addition of some TefGel on the
mix elbow and inside of the hose to make it easily removable for next time.
BTW, if anyone needs one, my colleague has one of the 2" stainless male/male
couplings that connects the transition piece and the mix elbow.
Dennis C.
Touche' 35-1 #83
Mandeville, LA
>________________________________
> From: Robert Abbott <robertabb...@eastlink.ca>
>To: Dennis C. <capt...@yahoo.com>; cnc-list@cnc-list.com
>Sent: Friday, November 16, 2012 10:57 AM
>Subject: Yanmar exhaust mix elbow pluggage question/survey
>
>
>Dennis:
>
>Questions: When you say "you cleaned the exhaust elbow", was it
only the 'U' shaped piece you took off to clean or did you remove
the whole assembly via the 4 bolts from the exhaust manifold?
>
>If it was only the actual 'U' shaped mixing elbow, how did you
remove it from the 'coupler' that attaches it to the piece that
bolts to the exhaust manifold?
>
>My engine is a Yanmar 2GMF, 1984.......spent 21 years in fresh
water and the last 7 seasons in salt water.
>
>I actually have an old, complete unit in my garage removed and
replaced earlier this season from a C&C 32 here that was
mostly fresh water used. The actual mixing elbow was badly
corroded inside and it split causing both water and gas leakage.
When I saw it it made me wonder about the condition mine is in.
>
>Regards
>Bob Abbott
>AZURA
>C&C 32 - 84
>Halifax, N.S.
>
>
>
>
>
>On 2012/11/16 11:57 AM, Dennis C. wrote:
>
>I just cleaned the exhaust elbow on a Yanmar 2GM on a 29 MK? for a client for
>the second time in 3-4 years. I have other friends with Yanmars who have
>never had to clean the elbow.
>>
>>This 29 rarely motors longer than from the slip to the harbor
entrance and back. The other boats sometimes motor long
distances.
>>
>>
>>
I am just curious as to the root cause for the pluggage. Is it usage? Is it
the model?
>>
>>
>>
>>For those listers that have frequent mix elbow pluggage, how do you use your
>>Yanmar? Which Yanmar do you have? Do you motor for long periods or just to
>>the harbor entrance and back? Could frequent short trips hasten pluggage?
>>Does long periods of motoring prevent pluggage?
>>
>>
>>Dennis C.
>>Touche' 35-1 #83
>>Mandeville, LA
>>
>>
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