Join Date: Apr 2016
Location: Dublin, Ireland
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Re: Clogged Yanmar mixing elbow?
Hi All (even though it's 3 years since the last post!).
I have a Yanmar 3GMD and recently noticed a deterioration in engine performance. There was a lot of black smoke and occasionally, a black inky trail in the water. Eventually, it worsened to the point that, 2 weeks ago it would only idle.
It turned out that the outlet from the exhaust manifold was completely clogged to the point that I don't understand how the engine ran at all - let alone how the black smoke even made it out of the exhaust.
It wasn't just blocked with carbon - there was a hard rust formation which had, over time, almost completely clogged it.
I took off the manifold and cleared out the offending port and brought the part to a local machine shop to have the flange face refinished.
In my case the elbow isn't an elbow at all but just a short pipe with a flange which connects to the exhaust manifold block (with gasket in between).
Once all reassembled the engine ran like a dream. It had been slowly choked to death by an ever decreasing means of exhalation. From now on it's now on my list of things to check every 2 years.
BTW the engine is 32 years old and I suspect this had never been looked at previously!