Yanmar Tips

[MidLandOne]

Originally Posted by CSY Man

As for the Max continous RPM, you say 85%.
Is still a special recommedation for Yanmar due to their designs, or is it general for most diesels?

I have heard 70% of max contious as the target, and have been running my Perkins 4-108 at that speed:
Max RPM 4000, max contious 3000, so I have been running at 2100 RPM and the engine seems to like it..No smoke, fuel consumtion 0.55 gallons per hour, minimal oil consumption and no vibration.

85% would be 2550 RPM, and it seems kind of "busy" at that speed.

Will take a moment to get to the 85% bit but bear with me .

Engine manufacturers describe their various ratings for their engines based on the service they are targeted to - so, for instance, the same engine may be governed to more revs so more fuel and power in an intermittent type duty such as a ferry with many stop starts, or for a patrol craft which may only require to run at full and high power sometimes and then only for short periods but run at slow cruise (compared to max speed) with low power for the rest of the time, than it would be for more onerous service. The less onerous the service the higher the rating for basically the same engine.

The highest rating is normally for engines targeted at pleasure boats and that will include a statement along the lines of must not be run at more than X rpm for more than Y hours in any 24 hours - Y is often around 2 hours. The lowest rating is for vessels that run continuously or are subject to heavy drive requirements such as tugs - normally referred to as continuous rating but one has to be careful in that some engine manufacturers (MTU and Cat for example) call the maximum rated revs of their non-continuous rated engines as being their Maximum Continuous Rating (or MCR) so can lead to confusion.

Across all these ratings the figure of operating at 85% maximum revs is a generally accepted rule for balancing engine service life and cruising the vessel at its required design cruise speed - so a design brief for a new vessel may state something along the lines of operational speed to be X knots at 85% (say) of the engines maximum rated revs for the particular service.

But one has to keep in mind that running a pleasure rated engine at 85% max revs may be the same as running a lower rated but otherwise pretty much the exact same engine (but governed to slower revs, less fuel and less power) at full revs. Small sailboat engines are basically all pleasure rated and have no alternative lesser commercial service type rating but one should keep the aforegoing in mind and so it is not a good thing, in my view, to run a pleasure rated engine at anything close to its maximum revs.

Similarly, in my view, it is not a bad thing to run a pleasure rated engine at cruise at revs less than 85% max as those could be the revs the engine would normally be run at if it had a more conservative rating for a commercial type service. In fact I suspect if you run it at somewhat less than 85% a longer and more reliable life will accrue but I have no evidence of that and furthermore most engines in pleasure boats die of old age or lack of care rather than use. But I do know that pleasure rated engines in commercial vessels (sometimes done for lower initial engine capital cost reasons or for more power from lighter weight engine, or simply because the boat is actually a production boat whose builder meant it for the pleasure market not the commercial one) which are run for long periods every day, even at cruise, don't last.

In our own case we find we cruise at around 72-75% of max revs, that getting us to the point where many more revs (and hence fuel) is required to make significant increases in boat speed. It also causes the steering to rattle if we use higher revs (the turbulence from the prop on a semi balanced spade rudder feeds back through the light steering) .

[DeepFrz]

I have always heard 75/75. That is 75% power 75% of the time with a good alternative to run at 75% power for the first 1/2 hour of the day to warm up the oil and then 75% for 1/2 hour about 1/2 hour before shutting down. In between it can be run at lower power settings without problems. Apparently it's low oil temp. that will cause most of the problems and running it at low power settings will not heat up the oil to proper operating temps.

[Waving]

Before I order new cylinder liners does anyone happen to have four of them suitable for a 4107 ?

Thanks

[casual]

Overheating?I,have a Yanmar 4JH3E,While running at 2900 RPM'S I,have No problems.I,Ran aground while backing and such to get off I,watched my temp go up almost to Max,as soon as I,got off it returned to normal operating temp,I,never had such a hard grounding before,is what happened normal?

[Wotname]

Originally Posted by GordMay

Caveat emptor: E. & O. E. - While every endeavour is made to ensure the information in this posting is correct, please email me if you find any mistakes so that they can be corrected.

SOME YANMAR DIESEL ENGINE TIPS:

Sizing:
..............
Propellers:

The propeller controls the maximum rpm under load. On Sailboats, there is no substitute for propeller diameter. Fit the largest diameter prop that will fit in the space (aperture) available*. You need to take into account the available gearbox ratios.
e.g. a 3GM30 with a 2.36:1 ratio gearbox will swing a 15 inch (380mm), a 2.61:1 ratio will swing a 16 inch (405mm) and a 3.2:1 ratio will swing an 18 inch (460mm) diameter propeller.

*Prop’ Clearances Rules of Thumb:
- The clearance between the tip of the prop and the hull = about 15% of Propeller Diameter
- The clearance between the rudder and the nearest point of the propeller = about 15% of Prop’ Diameter

- The clearance between a full keel and the leading edge of the propeller, measured half way out along the blade from the center of the shaft = about 30% of Prop’ Diameter, at half the radius from shaft centreline.
- The clearance between the prop strut bearing and the propeller hub = about equal to or 1.5 times Shaft Diameter.

Fit as large a diameter propeller as possible, taking into account the available gearbox ratios.
e.g. a 3GM30 with a 2.36:1 ratio gearbox will swing a 15 inch (380mm), a 2.61:1 ratio will swing a 16 inch (405mm) and a 3.2:1 ratio will swing an 18 inch (460mm) diameter propeller.

Propeller pitch is determined by boat speed and is calculated for individual boats.

Engine Gearbox Propeller diameter Recommended
model model ratio Inches millimeters Max. Displacement
1GM10 KM2P 2.21 12 295 < 5,000#
2.62 13 325
3.22 15 370

2GM20 KM2P 2.21 13 340 < 10,000#
2.62 15 375
3.22 17 425

3GM30 KM3P 2.36 15 380 < 15,000#
2.61 16 405
3.20 18 460

* Rotation: All Yanmar Engines are 'Righthand' (RH) Clockwise rotation, EXCEPT for Saildrives, which are 'Lefthand' (LH) or anti-clockwise.

...........

Caveat emptor: E. & O. E. - While every endeavour is made to ensure the information in this posting is correct, please email me if you find any mistakes so that they can be corrected.

Best regards, and happy motoring (when you can’t be sailing),
Gord

Old thread I know but hawk eyes here just picked a minor error and with Gord's blessing, I am offering the correction.

There is a minor error in the propeller section regarding rotation. The statement that all Yanmar engines (except sail drives) use RH props. While true for the engines have listed, it is not true for Yanmar YSx series. These all have LH props.

I understand ( but don't know for sure) that the S series also have CCW rotation (i.e. LH props).

Note: my emphasis in the quoted section

[Seymore]

If your Yanmar doesn't reach its rated maximum rpm and its maximum rpm goes lower over time, check the mixing elbow for a black diamond hard deposit. If you get this deposit often like this, check that you're not overpropped (that is, too big prop or too much pitch, too much prop for the engine).

Overpropping is like a truck lugging up a long hill.

[Esrom]

Hi Gord, saw your extensive Yanmar Tips and have a few questions.
You say that sea water cooled Yanmars run at 130f and fresh water versions run at around 140f, but Yanmar never offered an option of thermostat temperature for sea/fresh water on their earlier engines and still don't.
I have an old YSB and it runs at around 110f, which is way too cold for optimum combustion, causes carbonation and probably cylinder glazing.
I note that around 30 years ago Yanmar seem to have decided that their marine engine operating temperatures were way too cold and increased the thermostat rating of their new engines to 150f and 170F with heat exchanger. However they never offered any upgrade kits, or revised the thermostat and alarm sensors for their older engines. So us owners, on fresh waters, are still stuck with 110*f thermostats and cold-running engines. Do you have any opinions or solutions please?

[Compass790]

Originally Posted by Esrom

Hi Gord, saw your extensive Yanmar Tips and have a few questions.
You say that sea water cooled Yanmars run at 130f and fresh water versions run at around 140f, but Yanmar never offered an option of thermostat temperature for sea/fresh water on their earlier engines and still don't.
I have an old YSB and it runs at around 110f, which is way too cold for optimum combustion, causes carbonation and probably cylinder glazing.
I note that around 30 years ago Yanmar seem to have decided that their marine engine operating temperatures were way too cold and increased the thermostat rating of their new engines to 150f and 170F with heat exchanger. However they never offered any upgrade kits, or revised the thermostat and alarm sensors for their older engines. So us owners, on fresh waters, are still stuck with 110*f thermostats and cold-running engines. Do you have any opinions or solutions please?

Your ysb has lasted a long time as is but yes I'd want to do what you want to do if I was exclusively in fresh water.
Gord may have a more elegant solution but I would take existing thermostat & look in a chain car parts place in the thermostat rack & see if there is anything close to the dimensions of the Yanmar thermostat. I'm a tinkerer/modifier so would find a way to make one fit but you may not be comfortable with that.
You mite get more answers if you started another thread but its your first post I see. Welcome to CF.

[a64pilot]

You can’t run a raw water cooled engine that lives in salt water very warm, if you do the calcium carbonate I believe precipitates out and clogs water passages, contrary to what you think often the warmer water gets, the less it will hold in suspension. I believe it’s sugar that confuses us as anyone can tell you more sugar will dissolve in hot water than cold, but that’s not true for everything.

Leave it alone, it’s run fine for decades as is

[Esrom]

Hi a64pilot, thanks for your suggestion, but as I stated, I'm a fresh water lake sailor and this boat has never seen salt water in its long life. I understand about the aggressive corrosion and salt deposit problems of warm seawater, but as Gord May said in his excellent "Yanmar Tips" posting, 130 degrees is good for Yanmar seawater operation and 140 is better if in fresh water. However the old Yanmars came with 110* thermostats and 140* temp alarm sensors and Yanmar never bothered to increase those ratings for their spare parts, when they increased the operating temp for all their newer engines.
Sure the motor runs, but it cokes-up, has smelly (unburned) exhaust and runs rough, same as any diesel will if it's consistently too cold.

[Esrom]

Originally Posted by Compass790

Your ysb has lasted a long time as is but yes I'd want to do what you want to do if I was exclusively in fresh water.
Gord may have a more elegant solution but I would take existing thermostat & look in a chain car parts place in the thermostat rack & see if there is anything close to the dimensions of the Yanmar thermostat. I'm a tinkerer/modifier so would find a way to make one fit but you may not be comfortable with that.
You mite get more answers if you started another thread but its your first post I see. Welcome to CF.

Hi Compass 790, thanks for your suggestions. I've already looked in the "Gates" aftermarket thermostat catalogue for a thermostat to fit the YSB. They have some, but the lowest temp made is 170* for auto use, and that's a bit too hot.
I've written to Posiedon Marine of Sweden, who make OEM marine thermostats, and asked if they have a 140*f (60*C) thermostat and a 155*f temp alarm sensor for the YSB. Maybe they will help?

[GreenWave]

Originally Posted by casual

Overheating?I,have a Yanmar 4JH3E,While running at 2900 RPM'S I,have No problems.I,Ran aground while backing and such to get off I,watched my temp go up almost to Max,as soon as I,got off it returned to normal operating temp,I,never had such a hard grounding before,is what happened normal?

Maybe the grounding temporarily blocked the through hull for water intake?

[a64pilot]

An issue with changing the operating temp of an engine that has run for a long time at a lower temp is that you will change the clearances somewhat as of course warm up metal and it expands.
Yanmar’s are famous for being smoky, it’s because frankly they have an old outdated inefficient combustion chamber design that has little swirl. It’s a normal operating for a Yanmar, they are going to be smoky from unburned fuel, higher Cetane fuel helps tremendously. It almost eliminated my greasy stern. Plus your injectors may need cleaning and a dirty burning Yanmar will varnish up an injector much faster than a clean burning motor will.

[Compass790]

Originally Posted by Esrom

Hi Compass 790, thanks for your suggestions. I've already looked in the "Gates" aftermarket thermostat catalogue for a thermostat to fit the YSB. They have some, but the lowest temp made is 170* for auto use, and that's a bit too hot.
I've written to Posiedon Marine of Sweden, who make OEM marine thermostats, and asked if they have a 140*f (60*C) thermostat and a 155*f temp alarm sensor for the YSB. Maybe they will help?

I'm curious as to why you say 170F is too hot? Please explain. Why not try it if you can make it fit?
A64 pilot has a point about increasing temp affecting things but I would just monitor oil pressure when you change the thermostat. As the oil gets hotter it's viscosity decreases so oil pressure drops.
You would be fine unless your bearing clearances were excessive anyway. Your ysb8 is built with the same bearing clearances as a radiator equipped engine. In fact they used the same engines in generators & pumps.
How many hours on your YSB8? Actually it should burn quite clean at steady revs courtesy of it's 23:1 compression ratio. If you are revving it up the crude injection pump dumps a lot of fuel in it before the revs rise making an over fuel condition temporarily which causes it to blow black smoke. Should stop blowing smoke soon after revs stabilise. If it's a dirty smoker you need a compression & injector test. Might be it's time for new rings at least as it's not a young motor.
The other thing to watch out for is overloading, Can you reach at least 3000rpm under way in ideal conditions?
We have a YSM8 which is the same mostly ( slightly better injection pump) & once it was rebuilt it burns very clean even with tho it has the original thermostat since it lives in the sea.
Having said all that I agree with your idea to put a fresh water only thermostat in it. Hope you report back how it works if you find one, I'm curious.
Did think about converting ours to fresh water cooling but figured it's lasted ages anyway & want a bigger boat and or motor.
Good luck with your search.

[Yowieboy]

Hello dear experts,

please allow me to hop on this thread to pose a question (or two, actually) related to a Yanmar 1GM10B engine, specifically its (missing) thermostat. Last year, I bought a 25ft Yamaha sailboat in good condition that came with this engine. It's about 18 years old but had only about 500 hours on the meter. The boat had been kept on the hard in a marina for many years and used mainly for weekend and day sailing, with the engine mostly just for leaving and re-entering the harbor. Now I keep the boat permanently in the water and have a somewhat different usage pattern, but I also don't use the engine all that much. Occasional motoring and motor-sailing, with the engine running for a number of hours at most.
I know almost nothing about diesel engines (it's my first boat with an inboard diesel) and I am not mechanically inclined or gifted at all (also not well equipped in terms of tools etc.). So far the only thing I've done is change the oil and oil filter. Thankfully, the engine has never given me any trouble, it starts quickly and runs fine. It does produce a fair bit of vibration and a rather loud kind of metal 'tack tack' kind of sound at idle but at higher revs (sort of midrange, judged by the power, there is no rev counter), the vibrations are much lower, and the sound also settles down. No major complaints there. Okay, so what's the prob, you ask (sorry for the long preamble). Well, I was informed by someone more knowledgeable that my engine apparently has no thermostat, just a bypass hose where one would be (see attached photos). This modification probably was done at some previous point in the boat's life. My question is, how unusual or possibly harmful is this?

And I have another question.
When I said that this engine has given me no trouble, this was true so far, but very recently (last week) I had to motor for about 5 hours at a stretch. During this time, I had to do a bit of evasive action and pushed the throttle to full power for maybe 15 minutes, something which I don't do normally (my usual throttle position is at about 70 percent or so). To my dismay, I noticed that the cooling water (raw seawater cooling) being pumped out of the outlet on the stern suddenly had turned almost black (normally it's just regular water color), and there also was a lot more smoke (or vapor, rather?) than usual. There also was an 'exhausty' kind of smell . After I pulled the throttle back down to its usual position, things returned to normal. Fortunately the engine continued to run fine also thereafter. I've since briefly tried full power a few times, and the same thing started to occur again. (I didn't want to push my luck and do it too long.) Now this has given me pause, especially as some web searching seems to indicate that this could be indicative of a serious exhaust corrosion problem.

Any advice from people in the know will be gratefully received.