Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 24-09-2011, 18:00   #16
Senior Cruiser
 
S/V Antares's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: Annapolis, Bahamas
Boat: 1983 Gulfstar 36
Posts: 1,249
Images: 1
Re: The right way to run a diesel

I see a lot of black transoms out there. I think there is a tendency to overprop and get hull speed at lower than full throttle / full RPM. Especially on sailboats. Power boaters tend to spend a lot mor time on this. IMHO ...thats all
__________________

__________________
Will & Muffin
Lucy the dog

"Yes, well.. perhaps some more wine" (Julia Child)
S/V Antares is offline   Reply With Quote
Old 24-09-2011, 18:07   #17
cruiser

Join Date: Aug 2011
Location: Tampa Bay area
Boat: Hunter 31'
Posts: 5,731
Re: The right way to run a diesel

Quote:
Originally Posted by Morgan3820 View Post
I just recently noticed the following in my operator's manual for my Yanmar 4JH-2:

Stop the engine in accordance with the following procedures.
1. Stop the boat.


Put the remote control handle in
NEUTRAL and

reduce the engine speed to the lowest speed.
2. Be sure to race the engine before stopping it.
See 4.6(7)

3. Cool down the engine at low speed (1500rpm or

lower) for about 5 minutes.

Why should I race the engine before stopping it? I do not understand.
What I have been told is that it blows out any accumulating carbon in the exhaust hose. Someone told me that this is especially important if there's a u-bend in the exhaust hose because carbon can particularly build up there.

That doesn't from from my mechanic. It comes from a friend who has the same engine as mine, which is a 3 piston, 20 hp fresh water cooled Yanmar.
__________________

__________________
Rakuflames is offline   Reply With Quote
Old 24-09-2011, 18:16   #18
Registered User
 
four winds's Avatar

Join Date: Oct 2010
Location: Wandering the US Gulf Coast
Boat: 78 Pearson323 Four Winds
Posts: 2,138
Re: The right way to run a diesel

Not sure why anyone would think all diesels are operated in the same manner. They have been around for many decades in sizes ranging from a lunchbox to a locomotive.

It's a mistake to ask the op's question in a generic sense and not in regard to a specific engine.

What engine is the OP wishing to know about?

The service manual for mine states to motor away at 50% rated rpm (1800 rpm) for the first 5 minutes (after 3 minutes warmup at 1200 rpm), and then cruise at 80% of rated rpm (~2900 rpm), and when needed use full rated rpm (3600 rpm) for no more hour at a time. So it's actually OK to redline the engine for an hour at a time. And cruise at 80% of redline all day long.

Further, it states after docking to idle for 5 minutes to cool the engine and then throttle up to max for 30 seconds and back to idle then shut down.
__________________
four winds is offline   Reply With Quote
Old 24-09-2011, 18:28   #19
Marine Service Provider

Join Date: Nov 2008
Posts: 1,249
Re: The right way to run a diesel

Westerbeke 30b three.

Guess I should just check my manual.
__________________
off-the-grid is offline   Reply With Quote
Old 24-09-2011, 18:37   #20
Registered User
 
four winds's Avatar

Join Date: Oct 2010
Location: Wandering the US Gulf Coast
Boat: 78 Pearson323 Four Winds
Posts: 2,138
Re: The right way to run a diesel

Quote:
Originally Posted by grunzster View Post
Westerbeke 30b three.

Guess I should just check my manual.
Yes, each time I get a new piece of equipment I read the manual from cover to cover like it's a novel. Operating manual, and service manual.

You would be surprised how much you can learn from that, even if one is not mechanically inclined.
__________________
four winds is offline   Reply With Quote
Old 24-09-2011, 18:52   #21
Registered User
 
bobsadler's Avatar

Join Date: Feb 2008
Location: Shenzhen, China
Boat: Nauticat 42 (Jersey, U.K.)
Posts: 385
Send a message via Skype™ to bobsadler
Re: The Right Way to Run a Diesel

from my Yanmar 4LH-HTE manual:

"When the engine is operated at a low idling speed (below 1000rpm) for a long time (over 2 hours), excess carbon and fuel residue tends to accumulate due to incomplete combustion.

Carbon deposits on the injection holes of the fuel injection valve, exhaust valave, the turbine blades of the turbo-charger etc. cause a drop in engine output, knocking and other troubles. To prevent these problems, be sure to blow off the carbon accumulations by full speed operation.

Operate the engine at over 2500rpm for one minute in every two (2) hours of continuous low idling operation."
__________________
Bob
SV Karen M
http://www.freewebs.com/svkarenm/
bobsadler is offline   Reply With Quote
Old 24-09-2011, 20:16   #22
Registered User

Join Date: Jul 2010
Location: Aruba, Dutch Caribbean
Boat: Columbia, 43 "Tranquilo"
Posts: 26
Re: The Right Way to Run a Diesel

9 years ago I rebuild my Perkins 4-108 with a mechanic friend. Everything new! While bleeding it, friend was in the engine compartment and me cranking at the helm at WOT. As usual, with the pain in the ass to bleed Perkins, it took several tries. At one point I decided to give the starter a good cool off period and walked away leaving behind the lever at WOT.
The mechanic stayed behind to bleed once more. Before I returned he jumped the solenoid and she fired up racing away at full gas. Before he could get topsides to ease off on the gas, several seconds passed with the engine running at full revs.
I was shocked when he told me what happened but I have never, ever had any issues with this engine so far.
And whatever Cabo-Dude said in post # 4
__________________
Tranquilo is offline   Reply With Quote
Old 28-09-2011, 17:28   #23
Eternal Member
 
Chief Engineer's Avatar

Join Date: Aug 2006
Location: North of Baltimore
Boat: Ericson 27 & 18' Herrmann Catboat
Posts: 3,798
Re: The Right Way to Run a Diesel

I tried to explain to an owner that excessive running under no load situations is not good for the engine......on one occasion I told this person that running out of gear at WOT will cause smoking due to overfueling.......The vessel had been taken for a seatrial.....no smoke under load WOT.......

Person got another mechanic who said the compression is a "couple hundred low on all cylinders"....engine is now torn apart......

Jiminy....that particular diesel...will not start "a couple hundred psi low".

I wish I had that Kreskinesque claravoyance to do a compression test like that.

Funny thing though...no oil smoke...at all
__________________
Chief Engineer is offline   Reply With Quote
Old 28-09-2011, 17:39   #24
Registered User

Join Date: Apr 2011
Posts: 2,243
Re: The Right Way to Run a Diesel

Quote:
Originally Posted by grunzster View Post
I've head some people say you need to run a diesel hard, otherwise you may shorten it's life.

I've heard some people say, they only cruise at a very moderate rpm, and that constantly running at a high rpm is bad for it.

And I've recently heard someone say that the first one is only true with old diesels.

So which one is actually true?
When it comes to a typical sailboat diesel, terms like hard and high rpm are very relative.

My Universal is 1 litre, and produces 24hp at 3K rpm.

Contrast that to a typical automotive gasoline engine, producing maybe 100hp per litre at 6.5K rpm with a turbocharger.

Mechanical wear is obviously going to be less of a worry, and take many more hours of running, with the marine diesel. Here the problem is more likely to be carbon and soot buildup from the engine not working hard enough.
__________________
MarkSF is offline   Reply With Quote
Old 28-09-2011, 17:45   #25
Registered User

Join Date: Apr 2011
Posts: 2,243
Re: The right way to run a diesel

Quote:
Originally Posted by boatman61 View Post
I've heard its bad to run them at a constant rev rate for long periods... either raise or drop revs by a few hundred for a while...
I think that comment applies to running in any engine. Avoid long periods at constant, high rpm and load. The best initial running-in involves driving gently mostly but progressively extending the rpm for short periods. That way you loosen up any parts that are tight without causing excessive heat in the tight spots.

I did this for the first 500 miles on my VW Jetta's 2.5 and the engine is great now - loads of power and zero oil consumption. Maybe it would have been like this anyway? Who knows?
__________________
MarkSF is offline   Reply With Quote
Old 28-09-2011, 17:54   #26
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,368
Re: The Right Way to Run a Diesel

this discussion has repeated on here many times. There seems to be no one answer. Truckers let their engines idle for as much as 1/3 of the life of the engine, and nothing is more of a concern to them than engine life. Many identical marine diesels are rate at differnt max rpm's based on the stated use. (recreational, commercial and continuous duty) The same engine for continuos duty may be rated at 2600 rpm and for rec use 3500 rpm. That would indicate to me that lower rpm is better.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is online now   Reply With Quote
Old 28-09-2011, 18:32   #27
Registered User
 
cat man do's Avatar

Join Date: Aug 2006
Location: Brisbane Australia [until the boats launched]
Boat: 50ft powercat, light,long and low powered
Posts: 4,409
Images: 36
Re: The right way to run a diesel

Quote:
Originally Posted by bdbcat View Post
Folks...

Anecdotally, ....

I have two Cummins BT5.9M, 220 hp, in a 50' trawler catamaran. 11 years old.

Currently have about 10,000 hours each, and 95% of that time has been at a power level of 10-20%, based on fuel flow rate. No special effort to rev to max occasionally. Lots of "trawler miles" at 6 kts.
I have to ask

If 95% of your time is at 10-20% load to produce 6 knots, why not have smaller, lighter, cheaper engines that push it at 6 knots?

That was my reasoning behind having 65hpx2 (peak torque 50hp at 1600rpm) in a 50ft cat, because most of the time you are running at slow speed anyway.

And what sort of cat?
__________________
"Money can't buy you happiness but it can buy you a yacht large enough to pull up right alongside it"...............David Lee Roth
Long Distance Motorboat Cruising It Is Possible on a Small Budget
cat man do is offline   Reply With Quote
Old 28-09-2011, 19:40   #28
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: The Right Way to Run a Diesel

Quote:
If 95% of your time is at 10-20% load to produce 6 knots, why not have smaller, lighter, cheaper engines that push it at 6 knots?
One answer is because the manufacturers install the larger engines because people that don't know anything want them.
__________________
DeepFrz is offline   Reply With Quote
Old 28-09-2011, 19:45   #29
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,368
Re: The right way to run a diesel

Quote:
Originally Posted by cat man do View Post
I have to ask

If 95% of your time is at 10-20% load to produce 6 knots, why not have smaller, lighter, cheaper engines that push it at 6 knots?

That was my reasoning behind having 65hpx2 (peak torque 50hp at 1600rpm) in a 50ft cat, because most of the time you are running at slow speed anyway.

And what sort of cat?
Maybe he wants to run around at 40 knots when being chased by pirates... or the day after payday.....
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is online now   Reply With Quote
Old 28-09-2011, 20:36   #30
Registered User

Join Date: Sep 2010
Posts: 793
Re: The Right Way to Run a Diesel

I think by far the best advice is to read the manual for YOUR engine. They vary a lot in design, components, ratings, etc. What's right for one may be wrong for another.

As an example, some of the "advice" given here to always run at 85% to 95% load directly contradicts what the manual for my engines says. I'm sure that "advice" is correct for some engine out there in the world, but it would be very bad advice for mine and would void the warranty.
__________________

__________________
twistedtree is offline   Reply With Quote
Reply

Tags
diesel

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Diesel RIB Tenders . . . The Holy Grail ? capcook Auxiliary Equipment & Dinghy 3 02-09-2011 23:06
Do Not Use Biocide Journeyman Engines and Propulsion Systems 37 24-07-2011 19:47
For Sale: 3.5kw Diesel Marine Genset, Kubota Power, Ultra-Compact MoonlightSailor Classifieds Archive 0 18-07-2011 21:28
Long Way from Home - Diesel Trouble Tia Bu Engines and Propulsion Systems 17 29-06-2011 17:22



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:35.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.