Yanmars

Many boats that I am looking to purchase have Yanmar diesels. I think the most popular ones in the size range that I am interested in are the 240, 315 and 370 versions.

These engines are supposed to be wound pretty tight and light weight. Has anyone heard any actual stories concerning meltdowns or serious repairs? I have heard from a Yanmar tech*that the 315 is the bastard of the bunch.


-- Edited by Doc on Monday 22nd of August 2011 09:12:45 AM

Interesting post, Doc. I have been back and forth on a 42' boat with Yanmars & have basically the same question. I know very little about them other than they run at high rpms.

I had a small Yanmar that turned higher than most (3450rpm) and found it to be an excellent engine, a tad noisy but started always even in cold weather w/o glow plugs or other heaters. Had direct injection rather than the pre-chamber. Didn't like the Kansaki gear that came with it. Very noisy! In our pleasure boats I don't think higher speed diesels should be regarded any differently than others. Nobody seems to be able to wear out even the old Lehman. Life expectancy of a pleasure boat engine is usually regarded w commercial maintenance and should never so as they almost always get far far less and almost never get properly worn out. The vibration of higher frequency (rpm) and lower weight engines should be less and easier to control so lightweight high speed engines should be smoother. There was a 36' GB on YW that had the Lehmans removed and replaced w smaller (55hp) Yanmars. A conversation w him should be very interesting. I've heard some negative stuff about the Yanmar brand but can't recall any specifics. Seemed to me it came from a dealer of brand X.

The modern Mainships and and many* modern Albins all have Yanmars of various versions. You could go on those sites and probably learn a lot. And of course there is boatdiesel.com

*http://albinowners.com/aog/index.php?sid=354678ec0e1490661281b17808f8c6a5

*http://groups.yahoo.com/group/mainship/

*

I have had smaller Yanmars on a couple of boats and they always ran perfectly with no issues whatsoever.

The only comment I have is about their relatively low torque at low RPMs. I used to find docking could be somewhat problematic with the Yanmars because they always needed a good shot of RPMs to get the boat to respond at low speed whether in forward or in reverse.*

Our current boat has much higher low end torque which seems to give the prop a lot more bite in low speed manouevers; rarely do I have to touch the throttle, only the transmission *lever is worked.

The sensation of having low low end torque could be just a higher rpm engine w lower gears, smaller prop, lower pitch or any combination of the above. Going from an over propped boat to a properly propped boat could confuse the issue even more.*

You may well be correct Eric; I'm always confused when it comes to low/high torque vs low/high horsepower.*

We have more than15 twin engined SAR/towing vessels running several permutations of the 350*- 450 HP Yanmar 6LY engines. (6LY / 6LY3 / 6LY3A) powering Hamilton HJ274 water jets. Yearly run ranges from a couple of hundred hours to around one thousand.


Main problem over the years has been related to sooting because of running at too low load. These engines must be run hard all the time (cruise at 3100 RPM). After testing, Yanmar has advised us to completely avoid running at 1800*- 2200 RPM as the turbo has not really kicked in yet and the injectors are squiring even more fuel as the RPM's increase.

We perform Yanmar specified Commercial Duty Service every 250 hours.

At around 5000 hours engines are ripped out and completely rebuilt. As mentioned above, sooting has been discovered as the main source for wear and tear or premature breakdowns.

A friend of mine has one of the 315 HP's. His turbo went bust last summer. Was there a series of turbo breakdowns on these engines?*I believe there was a class action suit against Yanmar some time back. Can't remember if it was related to turbo problems.


-- Edited by r-rossow on Thursday 25th of August 2011 03:39:04 AM