I was speaking with my local Yanmar dealer (Richmond Boat Works). He gave me some information that may be of interest to 2GM/3GMxxF owners. First, the major reason for changing your oil is not dirt but water in the oil. Most sailboats do not get enough hours annually to justify changing the oil because of dirt but water will cause damage. Our H'31 is a 1985 model and only has about 600-700 hours total (about 50 hours/year). Second when your engine is in neutral you should be able to open the throttle to FULL and the engine should be able to tach 4000-4200 (he was emphatic that this will NOT hurt the engine). The governor on the engine (when motoring) is actually the propeller. When you motor (transmission engaged) you should be able to get at least 3600 RPM at WOT(wide open throttle). This way when you motor at 70-80% of WOT you will get optimum fuel economy and will not cause coking of the mixing elbow. If your engine is NOT developing these RPM's you may need some adjustments and/or re-propping. The last thing he mentioned is that these engines should be able to outlive the average boat/owner. Properly maintained they should achieve 12,000-15,000 hours with routine maintenance. I do not know if these numbers apply to other Yanmars or not.
Yanmar continued.
- Thread starter Steve Dion
- Start date
- Status
Big Bang Theory
Wow! I would be very careful about running up the engine to teh RPM suggested. I have COMPLETE factory manuals which are pretty specific as to redlines etc. Is this dealer trying to capitalize a new machine shop? Just wondering
Wow! I would be very careful about running up the engine to teh RPM suggested. I have COMPLETE factory manuals which are pretty specific as to redlines etc. Is this dealer trying to capitalize a new machine shop? Just wondering
Jeff... I don't think so.
Jeff: I know what you are saying, but these guys are really good. Mike has been working on Yanmar's since they came into the U.S. This is actually just a test to make sure that your throttle can open that far. It is just like a car, the engines will run over the max rpm. An engine on a car will not blow up if you run it over the redline in neutral (I would not hold it there for very long to test it though<grin>. Once you have established that your engine will rev that far you know that your throttle linkage is correct. As he mentioned the prop is really the governor and this is what controls the max RPM's. Then you need to check if you can get to the recommended RPM's under WOT. If you cannot then you know that your prop is not correct. Each inch of pitch or diameter will change your RPM's by 250-300 RPM's. In my case the original prop was a 15 x 12 which has too much pitch. Our maximum RPM's under WOT is 3000 RPM's. By taking 2 inches of pitch from the prop we should be able to get the correct RPM's (if everything and everybody is correct). PS: for owners of H'31 the prop tip clearance is approx. 2 1/8". If anyone cares.
Jeff: I know what you are saying, but these guys are really good. Mike has been working on Yanmar's since they came into the U.S. This is actually just a test to make sure that your throttle can open that far. It is just like a car, the engines will run over the max rpm. An engine on a car will not blow up if you run it over the redline in neutral (I would not hold it there for very long to test it though<grin>. Once you have established that your engine will rev that far you know that your throttle linkage is correct. As he mentioned the prop is really the governor and this is what controls the max RPM's. Then you need to check if you can get to the recommended RPM's under WOT. If you cannot then you know that your prop is not correct. Each inch of pitch or diameter will change your RPM's by 250-300 RPM's. In my case the original prop was a 15 x 12 which has too much pitch. Our maximum RPM's under WOT is 3000 RPM's. By taking 2 inches of pitch from the prop we should be able to get the correct RPM's (if everything and everybody is correct). PS: for owners of H'31 the prop tip clearance is approx. 2 1/8". If anyone cares.
Wanna bet?
Steve There is quite a bit of difference between your Yanmar diesel and a gasoline auto engine. The reason the Yanmar does not blow is because it has a built in governor. Modern cars will not blow up because they have computers that cut the fuel supply at something over red line (usually about 500 RPM over redline). Older auto engines may not have rev limiters! Don't try flooring your classic Corvette's throttle in neutral to check the adjustment of the throttle cable. It will rev until either the valves float (not necessarily good) or it BLOWs!
Steve There is quite a bit of difference between your Yanmar diesel and a gasoline auto engine. The reason the Yanmar does not blow is because it has a built in governor. Modern cars will not blow up because they have computers that cut the fuel supply at something over red line (usually about 500 RPM over redline). Older auto engines may not have rev limiters! Don't try flooring your classic Corvette's throttle in neutral to check the adjustment of the throttle cable. It will rev until either the valves float (not necessarily good) or it BLOWs!
- Status