Roger Long
Senior Member
We have two Perkins 6.354 naturally aspirated engines in the museum that is our 1975 engine room. Hours unknown but estimated to be 6000 – 8000. The port engine does not use more oil than the width of the “Max” scratch line on the dipstick between 100 hour changes. The starboard takes about a gallon and a half between changes and needs top ups every 3 – 4 days when traveling.
Aside from the mystery of why two engines with identical service profiles are so different, there is the bigger mystery of where the oil is going. The drip pan of the starboard engine shows some leaks but not enough to account for more than a small portion of the lost oil. The exhaust smoke from the two engines is identical, the area around the outlets cleaner than I have seen on any boat, and both start instantly, even with weak batteries. I sometimes see a sheen in the water on startup or long idling periods forced by locks or no wake zones but, these are Perkins after all. Interestingly, this problem has gotten steadily better over the thousands of miles we have run since buying the boat last year. More interestingly, there is no visible difference between the two engines’ occasional exhaust sheens. The only difference I can detect is the amount of oil I am pouring through one engine and a tiny amount of oil in the starboard drip pan.
Both engines are under oil analysis showing normal wear for their age. Although I try to run them up to near WOT for 5 - 10 minutes every day or two, these engines are run very lightly in the 1400 – 1600 rpm range most of the time which gives us 7 knots. My GPS shows that our moving average over 1258 miles was 7.0 knots. We burned 448 gallons during that time which works out to 179 hours so 2.8 GPH. 2.8 / .056 = 50 HP or just 25 HP per engine on average. These 130 HP engines are running very lightly indeed but they seem happy.
Thoughts?
Aside from the mystery of why two engines with identical service profiles are so different, there is the bigger mystery of where the oil is going. The drip pan of the starboard engine shows some leaks but not enough to account for more than a small portion of the lost oil. The exhaust smoke from the two engines is identical, the area around the outlets cleaner than I have seen on any boat, and both start instantly, even with weak batteries. I sometimes see a sheen in the water on startup or long idling periods forced by locks or no wake zones but, these are Perkins after all. Interestingly, this problem has gotten steadily better over the thousands of miles we have run since buying the boat last year. More interestingly, there is no visible difference between the two engines’ occasional exhaust sheens. The only difference I can detect is the amount of oil I am pouring through one engine and a tiny amount of oil in the starboard drip pan.
Both engines are under oil analysis showing normal wear for their age. Although I try to run them up to near WOT for 5 - 10 minutes every day or two, these engines are run very lightly in the 1400 – 1600 rpm range most of the time which gives us 7 knots. My GPS shows that our moving average over 1258 miles was 7.0 knots. We burned 448 gallons during that time which works out to 179 hours so 2.8 GPH. 2.8 / .056 = 50 HP or just 25 HP per engine on average. These 130 HP engines are running very lightly indeed but they seem happy.
Thoughts?
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