Bruce in Bangkok wrote:
On Sat, 24 Nov 2007 23:49:00 -0500, Wayne.B
wrote:

On Sat, 24 Nov 2007 22:12:41 -0600, Brian Whatcott
wrote:

Diesels don't have this problem, and so are less wasteful at low
revs.
That's true but they have maintenance issues if run at low speed/low
load for extended periods of time.

Yes there "seems" to be that but mention of "it is bad to run the
engine at low poser" seems confined to the boating world. I've worked
many construction jobs where diesel engines were started in the
morning and shut down at the end of the day. During smoke breaks or
lunch they just sat there and idled. Cranes are a perfect example,
that spend most of their life at very low power settings.

Generator sets - I've never seen a gen set operating manual that said
"run this engine at high power settings".

Not that I'm advocating idling your diesel for days and days but I do
wonder about the people who worry about letting the engine idle. I've
seen people that would hardly let the poor old thing cool down before
stop-cocking it, "because it is bad to let the engine run at low
load".

The Perkins I have in the sail boat has a continuous rating of 3,000
RPM and for years I ran it at 1500 - 1800. When I overhauled it I
could see no evidence of abnormal wear or carbon or any other evidence
that slow running harmed anything.

I have the feeling that someone once said "it's not a good idea to
idle a diesel for a long time" and as the message passed from dockie
to dockie it became an urban legend and now everyone is worried about
idling the engine.

The issue with my motor, the Yanmar 2QM15, is that it runs cold at low
RPM. I can verify this. It's amazing how long it stays cold with no
load. This would be bad for it, right?

Stephen

"Stephen Trapani" wrote in
message ...

The issue with my motor, the Yanmar 2QM15, is that it runs
cold at low
RPM. I can verify this. It's amazing how long it stays
cold with no
load. This would be bad for it, right?


Yes. That is the main reason to not let a diesel sit at idle
too long. Low temp AND lower oil pressure at idle. For
years truck diesels have had a 'high idle' setting ( either
by air or electric solenoid, manual cable, or lately via
computer) so they can run them at night while parked.


SBV

On Sun, 25 Nov 2007 08:11:30 -0800, Stephen Trapani
wrote:

Bruce in Bangkok wrote:
On Sat, 24 Nov 2007 23:49:00 -0500, Wayne.B
wrote:

On Sat, 24 Nov 2007 22:12:41 -0600, Brian Whatcott
wrote:

snipped

The Perkins I have in the sail boat has a continuous rating of 3,000
RPM and for years I ran it at 1500 - 1800. When I overhauled it I
could see no evidence of abnormal wear or carbon or any other evidence
that slow running harmed anything.

I have the feeling that someone once said "it's not a good idea to
idle a diesel for a long time" and as the message passed from dockie
to dockie it became an urban legend and now everyone is worried about
idling the engine.

The issue with my motor, the Yanmar 2QM15, is that it runs cold at low
RPM. I can verify this. It's amazing how long it stays cold with no
load. This would be bad for it, right?

Stephen

If your engine runs cold put a thermostat in it. Your Yanmar should
warm up like any engine and stay the same temperature from then on.
Running an engine at a lower then designed temperature is not the way
to go.

Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

Bruce in Bangkok wrote:
On Sun, 25 Nov 2007 08:11:30 -0800, Stephen Trapani
wrote:

Bruce in Bangkok wrote:
On Sat, 24 Nov 2007 23:49:00 -0500, Wayne.B
wrote:

On Sat, 24 Nov 2007 22:12:41 -0600, Brian Whatcott
wrote:

snipped
The Perkins I have in the sail boat has a continuous rating of 3,000
RPM and for years I ran it at 1500 - 1800. When I overhauled it I
could see no evidence of abnormal wear or carbon or any other evidence
that slow running harmed anything.

I have the feeling that someone once said "it's not a good idea to
idle a diesel for a long time" and as the message passed from dockie
to dockie it became an urban legend and now everyone is worried about
idling the engine.
The issue with my motor, the Yanmar 2QM15, is that it runs cold at low
RPM. I can verify this. It's amazing how long it stays cold with no
load. This would be bad for it, right?

Stephen

If your engine runs cold put a thermostat in it. Your Yanmar should
warm up like any engine and stay the same temperature from then on.
Running an engine at a lower then designed temperature is not the way
to go.

Why didn't Yanmar put a thermostat in this engine? Is there any
disadvantage to having the thermostat?

Stephen

On Sun, 25 Nov 2007 17:49:19 -0800, Stephen Trapani
wrote:

Bruce in Bangkok wrote:
On Sun, 25 Nov 2007 08:11:30 -0800, Stephen Trapani
wrote:

Bruce in Bangkok wrote:
On Sat, 24 Nov 2007 23:49:00 -0500, Wayne.B
wrote:

On Sat, 24 Nov 2007 22:12:41 -0600, Brian Whatcott
wrote:

snipped
The Perkins I have in the sail boat has a continuous rating of 3,000
RPM and for years I ran it at 1500 - 1800. When I overhauled it I
could see no evidence of abnormal wear or carbon or any other evidence
that slow running harmed anything.

I have the feeling that someone once said "it's not a good idea to
idle a diesel for a long time" and as the message passed from dockie
to dockie it became an urban legend and now everyone is worried about
idling the engine.
The issue with my motor, the Yanmar 2QM15, is that it runs cold at low
RPM. I can verify this. It's amazing how long it stays cold with no
load. This would be bad for it, right?

Stephen

If your engine runs cold put a thermostat in it. Your Yanmar should
warm up like any engine and stay the same temperature from then on.
Running an engine at a lower then designed temperature is not the way
to go.

Why didn't Yanmar put a thermostat in this engine? Is there any
disadvantage to having the thermostat?

Stephen

Well, I think that they did. At least the 2GM20 I owned had a
thermostat and the parts book shows two, a normal temperature one for
freshwater cooling and a low temperature one for salt water cooling.


Bruce-in-Bangkok
(Note:remove underscores
from address for reply)