Monday, 10 October 2016

Northern Lights - Exhaust Injection Elbow Blues

Looks Good On The Outside, But Completely Rusted Out On The Inside
Our first maintenance job in Trinidad was to investigate why our Northern Lights generator was not coping with larger loads.

Valve or injector problems was the local agent's opinion (and mine), however the freelance mechanic they referred us to knew better. After asking some well focused questions he said he would pull the exhaust injection elbow off first.

I'm glad he did - it was found to be almost totally blocked by corrosion and accumulated soot.  The poor little diesel had been working against enormous back pressure for some time - no wonder it was feeling over loaded.

Now I was warned about this - my friend Dana on the sailing yacht Villa G had a similar experience. It seems that these generators are shipped from the factory with a - wait for it - cast iron injection elbow.  These just have to rust out very quickly and I think we were lucky to get over 1700 hours of service.

We did have a spare injection elbow on board, this one made from shiny cast 316L stainless steel - I'm told it will last three times as long as the cast iron version.  They just cost a little more, which is why they are considered "optional" - not standard equipment. With the new elbow fitted the machined returned to full power immediately, and we breathed a sigh of relief. This was the first part failure on our Northern Lights generator since new, we're still very impressed with the reliability.

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