I am the new owner of a 1984 Sirius 28 sailboat with a Yanmar 1gm and quickly learning the previous owner did very little regular maintenance on the engine. Despite the marine surveyor who stated the boat is in good shape, I have replaced the thermostat, zinc anode, primary and secondary fuel filters, oil filter, air filter, both engine and gearbox oil, seawater intake hoses, seacock, one rusty oil line and checked the exhaust elbow for blockages (none). The hull and prop have been cleaned and I am about to have the packing replaced in the stuffing box. Although this has been a terrific learning opportunity, the engine is still giving me some concerns. The engine starts easily and will reach a max of 3100 RPM in neutral, but only 2400 RPM when in gear which will get the boat up to 6kts. The exhaust is whitish in colour and there appears to be only a low amount of water being expelled from the exhaust, although I do not know what the normal amount should be. Additionally, when accelerating quickly there is a “clanking” noise in the engine compartment – there is no noise if the acceleration is gradual.
I’ve scoured the forums and internet to get some answers to no avail. I am able to perform some fairly basic repairs and would really appreciate any assistance you can provide to identifying potential reasons for the low RPM, whitish exhaust, low exhaust water outflow and “clanking” noise when accelerating quickly.
I’ve scoured the forums and internet to get some answers to no avail. I am able to perform some fairly basic repairs and would really appreciate any assistance you can provide to identifying potential reasons for the low RPM, whitish exhaust, low exhaust water outflow and “clanking” noise when accelerating quickly.