Join Date: Jan 2007
Location: The house is in Kingsport, TN. Boats are on Watauga Lake and in New Bern, NC
Thanked 40 Times in 36 Posts
Rep Power: 10
Re: 3JH2E Cruising RPM
We have the older Yanmar engine, a 3HM35F, and run it a lot. We have engine drive refrigeration and to keep the freezer frozen we run the engine one to one and a half hours a day 150+ days per year. For the last six years we have traveled to the Bahamas and back motoring 1000+ miles down in the ICW and many back.
In 2004 we bought the boat, a 1988 model, with 4000 hr on the engine. In 2010 on our way south at 5800 hr the oil consumption jumped from 1 qt per 50-100 hr to 1 qt per 5 to 7 hr. That fall we pulled the engine, and I took it to Mac Boring in Union, NJ for a complete overhaul. The mechanic who did the work said the engine was fine except that the rings in the aft most cylinder were corroded into the piston. He suspected that at some point in the engine's life salt water had entered that cylinder. (When we bought the boat it had significant repaired damage to the port quarter of the hull and some interior water damage.)
We motor at around 2200 rpm with a two blade prop. We charge the batteries and freeze the holding plate starting at 1800 rpm (to keep the alternator fan spinning and the alternator cool) dropping to idle as the charge rate falls off.
Other issues uncovered during the overhaul that had no bearing on the oil comsumption included all three chamber liners were cracked and the heat exchanger was badly fouled with lime.
1988 PSC 34
Last edited by wsmurdoch; 10-27-2013 at 05:47 PM.
Reason: I added the propeller size.