Re: [Amel Yacht Owners] engine cruising RPM

Kim Kimball <dhk@...>

As a chief engineer of a service vessel with > 10 diesel engines,  including train engines, our rule of thumb was to operate at the correct operating temperature for the engine in question. That should be available in the manufacturer's documentation for your engine.

That being said, our main engines often had turbos, and we often had a requirement to idle them for hours.

Removing and replacing a turbo was a royal PITA ... and low operating temperature (low RPM) causes both engines and turbos to accumulate carbon (valves, vanes ...)

I got good at  replacing cylinder heads (not equipped to swap out valves) and not so good at the occasional turbo replacement.

Operating temperature is your friend.  If, no matter what RPM you're running, you can't reach the operating temperature, the most common culprit is a thermostat.


On 7/9/18 12:34 PM, Ryan Meador [amelyachtowners] wrote:
Thank you all for the info.  As I predicted going in, there is no simple answer.  But I think I have some guides now.

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA

On Sun, Jul 8, 2018 at 4:06 PM Courtney Gorman <> [amelyachtowners] < <>> wrote:

Amen Porter well said

Sent from my iPhone

On Jul 8, 2018, at 12:41 PM, Porter McRoberts <>
[amelyachtowners] <
<>> wrote:


Mostly true. New long block 800 hours ago and New injectors about
400 hours ago.
It is a common rail.
On a different topic. We’re currently stuck in panama with a bad
boost pressure sensor.
I have envy of anyone who can unplug the computer and have the
engine run.
The concept that a computer controlled engine be installed in a
world cruising sailboat seems antithetical to the purpose of a
sailboat, and to ours in particular.
I’ve been training (at your knees, and especially Bill R’s) for
the past year to be as self sufficient as possible, and to be
thwarted by a stray electron underscores how vulnerable we are.
Our cruising buddies are on a 1984 trintella. Sailed from
Croatia. They are in year #5. Old Perkins runs like a boss. I
asked my buddy, who is in his own right a Jedi of machinery, how
often he changes his fuel filters.  He chuckled.  “I don’t think
I’ve needed to do that” he said. Pressure’s good. Engine runs well.
I had engine envy. Not that the Volvo isn’t a fine piece of
hardware, but.... it’s the intersection of important and
complicated. Not a good combo. Like I say. Thank God for sails,
and the fact that we sailors got around just fine for the first
1000 years without motors.

In short. Seems like diesels (or the industry and associated
standards) took a step back in the past 15 years putting
efficiency over simplicity. I think Nigel Calder would agree.

Have wonderful Sundays. Without this motor glitch we wouldn’t
have seen the incredibly beautiful town of El Valle up here in
the Panamanian cordillera.

Porter, Helen and crew
S/V Ibis
Panama City

Sent from my iPad

On Jul 7, 2018, at 6:30 PM, Teun BAAS
<> [amelyachtowners]
<>> wrote:

Hi Porter,

I understood you had a new VOLVO installed. If so, *and it is a
common rail*, then there is *NO* need to run the engine on high
rpms to “burn out the soot”.

This is the specific instruction I got this week from the SYDNEY
VOLVO technician installing my VOLVO D3 110 H here in NOUMEA NEW

Best Regards Teun

AMELIT  54 – 128


Jul 08, 2018 10:27:44

*Sent:* Sunday, July 08, 2018 10:24 AM
*Subject:* Re: [Amel Yacht Owners] engine cruising RPM

Thanks Mark.

If temp is the final data point, we cruise at about 79-80. What
should be the goal?

Thanks again!


Sent from my iPad

On Jul 7, 2018, at 11:13 AM, 'Mark Erdos'
<> [amelyachtowners]
<>> wrote:


It really doesn’t matter how you do it but you need to
create internal engine heat to clean out the engine. This is
done with a load on the engine. If in neutral, it will take
longer to create a load and heat. In gear while underway
will heat up the engine faster.

This is true for all diesel engines.

Where you run the RPM depends on the engine. Typically, 80%
of max power will heat up the engine nicely without too much
strain. This is also good for the turbocharger, if fitted
with one.

How long? At least every couple of hours while underway, if
not a little more frequently... We run ours up every hour
for about five minutes. This works for us.

Keep in mind, this is not just the ship’s engine but also
true for the genset. Running a genset without load will
cause carbon buildup. Keep the genset loaded when charging
batteries etc. We find it best to run a couple of AC units
or do a load of laundry etc. The battery charger only puts
load on the genset at the beginning of the charge cycle.

Hope this helps.

With best regards,



Sailing Vessel - Cream Puff - SM2K - #275

Currently cruising - Curacao <>

*Sent:* Saturday, July 7, 2018 11:35 AM
*Subject:* Re: [Amel Yacht Owners] engine cruising RPM

Ok. Bullshit aside.

I do have a few real questions, that I’ve had for a while.

It’s the same for all diesels. Yes?

Is “racing” out of gear best? I would think load would be
required to increase fuel consumption and thus heat. Fuel
burn>>heat dissipation 2/2 raw water flow.

Forget the rpm. Where is the throttle?  100% down? 80%?

And for how long?

Many thanks, as always to this great group.



Excuse the errors.

Sent from my IPhone <>

On Jul 7, 2018, at 9:02 AM, 'Mark Erdos'
<> [amelyachtowners]
<>> wrote:


Wow! Sorry. I didn’t realize I had to be so freaking
specific. Seriously! The essence of the post I made is
100% correct. I didn’t intend to make a verbatim quote
of the manual. If  I had, I would have used quotation
marks. I stated this is OUTLINED in the manual. I did
not say this is a DIRECT QUOTE from the manual. Geeez!
And, please note I did say 4JH4 manual, not 4JH3 as you
are quoting.

But if you want specific details of the JH4 Operation
Manual, publication number OAJH4-G00102, page 78. I
quote, “Periodically operate the engine near maximum
speed while underway. This will generate higher exhaust
temperatures, which help clean out hard carbon deposits,
maintain engine performance and prolong the life of the

This is below the section you quote about running it in
idle and speaks specifically about running the engine
_while underway_.

Regardless of whether this is done in neutral or in gear
while underway, the purpose of the procedure is to raise
the internal temperature of the engine periodically to
remove carbon build up. Carbon build up will kill a
diesel engine.

I’m feelin’ a little crabby today. Can you tell?

With best regards,



Sailing Vessel - Cream Puff - SM2K - #275

Currently cruising - Curacao <>

*Sent:* Saturday, July 7, 2018 3:20 AM
*Subject:* RE: [Amel Yacht Owners] engine cruising RPM

Hi Mark,

Regarding "Running a lower RPMs without load will
shorten the life of the engine unless it is pushed up at
least once per hour for about 5 minutes. This is
outlinede in the Yanmar operation manual."

This is not to challenge the veracity of your statement
but I cannot find that in my Yanmar manual. Maybe you
have a different manual and it would be helpful (really)
to have you quote what it says.

What my 4JH3-HTE Operation Manual says (on page 30
section 4.6) is:

"When operating the engine at low speed ffor long
periods of time, race the engine once every 2
hours"..."Racing the Engine, Morse Remote Control Handle
Pull out the handle lever...and shift the engine speed
from high to low several times...Racing the engine
removes carbon built up in the compustion chamber around
the fuel injection valve. Neglecting to race tthe engine
will cause the exhaust to turn black and lower the
efficiency of the engine".

In other words it says to gun the engine several times
while it is in neutral.

Like others, we vary my speed between 1600 and 2200 for
cruising and can cruise up to 2400 rpm. We also run it
at say 2800 for 5 minutes or so periodically. However, I
cannot find where Yanmar recommends this.  There are
postings in this group (not yours) that say to run it
full out for 5 minutes, even full out fo 30 minutes but
I don't think that is advisable. Seems that vibration is
higher and it might be hard on the transmission and c
drive as well.  Like most of us we vary the speed and
run it harder at times but we also do the "Racing"
procedure that is in our manual.

Bob and Suzanne, KAIMI #429

La Maddalena, Sardegna

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