After de-winterizing our recently purchased SM 2000 and starting the
engine, we rapidly blanketed the marina in what could easily have
been mistaken as a June fog on the Maine coast. Unlike fog it did
not lift or burn off as the day progressed.
Turns out the heat exchanger was at least 50% blocked with sea
grass, pine needles and other small debris as well as general crud.
Perhaps it was the restricted flow that resulted in extra high
temperatures on the exhaust side and perhaps steam and water pushing
back from the injection elbow into the turbo which was significantly
carboned up. After a thorough cleaning of both the heat exchanger
and turbo, the engine burns clean and now peaks at 4000 rpm. We
hadn't tried to run it up last fall, but after dewinterizing and
before this cleanup it seemed to flag at around 2600 rpm.
Photos of the heat exchanger core are posted under Aletes SM#240.
One can see the amount of buildup on the core tubes and pieces of
debris jammed into the tubes and laying in the end caps.
This experience leads to two questions.
1) How did this debris get through the strainer? It seems the
strainer basket does not have a compressible seal at the top or
bottom, and in fact has a bit of vertical play. Might there be
enough of a gap to allow a blade of sea grass or pine needle to
sneak around the strainer? Would adding a compressible gasket to
the top and bottom of the basket provide the requisite seal?
2) Why does the Volvo manual not mention maintenance on the heat
exchanger or on the turbo? From what we found, it would seem a look-
see would be appropriate at least every 500 hours.
Interested in the experience of others on these issues.
S/Y Aletes SM#240