I have a Volvo TDM 22 but diesels are diesels…
I encountered these symptoms on another boat… badly crusted propeller…
Other cause might be a faulty turbocharger. Generally, we tend to baby our engines and this is not good. I try to run at 80% or more power for 1 hour out of every 24 hrs of engine time.
Third possibility = a collapsed air filter. BTDT.
Good luck.. at least the trouble shooting should be easy.
SY Eleuthera, Amel Super Maramu 007
Porto Turistico Marina di Ragusa, Pontoon M15,
I bought my SM in Feb 2015 and there are still many systems I need to better understand. Most perplexing is I have seen declining engine RPMs since original survey. Originally boat produced about 3100 RPMs (Yanmar manual says 3600/3800 tops - but I do know Autoprop may limit that number) but has since declined to 1800. Not sure why as engine seems to run fine - easy start, no smoke, no roughness at any RPM. Racor and engine filters are new. Manual shut off valve in passageway is wide open (it actually will not shut off motor... but that's another issue). I do have an Autoprop which was serviced well over a year ago - but not sure - by previous owner. Only other engine oddity as it runs very cold - never over 130F. Boat has been in the water now for a little over a year with not much motor use. Any and all suggestions would be welcome.
La Bella Vita