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Old 30-06-2016, 09:47   #1
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Running my engine hard?

Hi, I have my first Inboard diesel boat and am living aboard.
It is a Morgan OI 33 Pilothouse (1980). I was told by the old guy I bought it from, that when I'm on long trips to just run steady at around 1900 rpm. A fellow sailor neighbor suggested that it is good for the engine to be really cranked up occasionally for a while. Is this true...if so, for how long and how often. At this time I'm doing very little sailing or motoring, because U'm working on restoring it.

Any advice would be appreciated!

PS. The engine is a Perkins 50hp.
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Old 30-06-2016, 09:53   #2
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Re: Running my engine hard?

Quote:
Originally Posted by Transition View Post
Hi, I have my first Inboard diesel boat and am living aboard.
It is a Morgan OI 33 Pilothouse (1980). I was told by the old guy I bought it from, that when I'm on long trips to just run steady at around 1900 rpm. A fellow sailor neighbor suggested that it is good for the engine to be really cranked up occasionally for a while. Is this true...if so, for how long and how often. At this time I'm doing very little sailing or motoring, because U'm working on restoring it.

Any advice would be appreciated!

PS. The engine is a Perkins 50hp.
My father had the same engine in his boat and ran it at 2000 RPM day in and day out for 25 years. He never ran it over 2000 rpm and never had a day's trouble with it. It was 35 years old and had more than 20,000 hours on it when he sold it last year.

Yanmar recommends running their engines up to near the redline under load for a few minutes, every few hours, if you are running very slowly. I do that. Yanmar and Perkins are different in a number of respects. For one thing, 1900 RPM might not actually be "slow running" on that engine (my Yanmar has redline of 3900).

YMMV.
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Old 30-06-2016, 10:00   #3
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Re: Running my engine hard?

I'm in the blow it out every now and again crowd, but only once it is fully warmed up, and slowly advance the throttle and leave it near full throttle for a few minutes, like may 5 min, then slowly reduce back to cruise RPM, maybe once a day if your running for 24 hours or so.
Slowly warm it up before working it hard, and allow it to slowly cool down before shutting it down after working it hard, but as most of us anchor, that almost always allows for a very good cool down anyway.
If it burns some oil don't worry, until it gets so it's blowing an obnoxious amount of smoke, is hard to start from low compression or has lost too much power, but oil consumption is nothing to worry about.

Running it hard every now and again will point out your cooling system is needing service etc as it may get hot worked hard, and it shouldn't.
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Old 30-06-2016, 10:21   #4
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Re: Running my engine hard?

Our Perkins spent most of it's 4500hrs and 40 odd years at low power. I decided to blow the carbon out one day. At full chat it gave up in about 20 minutes. I would suggest you treat it just like the last guy and avoid any surprises. If you knew that the rings, valves etc were in great shape full power would be fine.
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Old 30-06-2016, 10:23   #5
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Re: Running my engine hard?

If you run it at constant rpm for hours on end, maybe you should use aircraft oil with ashless dispersant, otherwise, blow it out every once in a while.
Years ago, when I was working at Pt Mugu missile range, the mechanics said the PT boats were governed at 1700 RPM, and wore out the big Packards regularly. The AVRs (target boats) were allowed to run WOT -they were shooting at them- and the engines lasted much longer.
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Old 30-06-2016, 11:04   #6
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Re: Running my engine hard?

Thank you all for your input. I am a bit confused though, because I'm hear "do" and "don't.

Just to recap. I'm a live aboard, I start the engine a couple of times a week sitting at the dock, and take her out about once a month, just to make her "happy" (I hope?). If I was taking a long trip, I definitely would keep her at a steady 1900 rpm which runs her around 4 knots. Because I'm NOT getting her out as much as I'd like to right now, is there a "general consensus" as to what is the best way to keep her running. I have never taken the rev's right the way up. At about 2700 rev's she seems to run around 7 knot's. Forgive any naÔvetť on my part. I am quite a newbie.


Thank you once again!


Mark
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Old 30-06-2016, 11:17   #7
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Re: Running my engine hard?

Nothing wrong with running it hard now and then. My guess is not necessary though. The Perkins are not known for carboning up like the Yanmar's are though. If you boat is propped for 2000 rpm you may not be able to run it up.
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Old 30-06-2016, 11:48   #8
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Re: Running my engine hard?

A lot of diesels like to be run at about 80-85% of max rpm with occasional WOT to blow it out. If you run it at idle a lot you want to run it hard for a while to clean it out and to keep the cylinder walls from glazing.
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Old 30-06-2016, 13:57   #9
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Re: Running my engine hard?

Running an old engine hard that has never been run hard may knock some carbon loose? I would progressively run it a little harder each time until I reached governed rpm. I am not in the camp of run them hard all the time. I personally think that an engine should reach governed rpm regularly if for no other reason than an early warning of potential fuel starvation or overheating issues that you would not otherwise know until it was too late. On shut down I rev mine to max as it reaches max rpm pull the kill cable , the theory is that additional oil will be deposited on the cylinders and valves to help prevent some corrosion and leave a little on the rings for the next start up, reality may be that it is getting burned as if it were diesel ? DON"T DO THIS to a turbo charged engine !
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Old 30-06-2016, 14:00   #10
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Re: Running my engine hard?

Quote:
Originally Posted by Transition View Post
Thank you all for your input. I am a bit confused though, because I hear "do" and "don't.
That's funny and made me chuckle. It's very typical of Cruisers Forum responses for some questions, but not too many people point that out.

At the end of the day it's perhaps important to appreciate that this is a public forum and some questions always have two opposing views and there is no ‘right’ or ‘wrong’ answer. Here are a few other questions that always result in answers just like yours:

Should I leave my gear engaged or in neutral when I'm sailing (motor is turned off).

On my Cat, is it best to run both motors or just one motor?

Planning to replace my engine soon, should I stick with diesel or go electric.

When I close up my boat when I am away, should I turn the power switch to off or leave it on?

Should I have bananas on my boat?

Is it really bad luck to change a boat’s name?

And that’s not even going into religion, guns, climate change or politics. I could go on, but I’m sure you get the idea. And when you read back through the odd post there’s often two poles of opinion, particularly to a yes/no question such as you’ve asked. And don’t all such questions just invite attribution bias? But that’s another post for another day.

Polarity of opinions is one of the great strengths Cruisers Forum and makes it interesting. At the other end of the spectrum, its biggest weakness is that’s so US centric. Irrespective all responses are valid (in my view), it’s just whether you, the poster, chooses to give them credibility. And it’s not my intent to mock your post, but it helps, I feel, to provide better information and background when posing questions.

Like you don’t include the motor’s model other than 50hp Perkins, not even the year of manufacture. Perhaps it’s a 1980 engine installed when the boat was new. But it could it could have been second hand even then (not uncommon) or perhaps the current engine is much newer, you don’t say. I don’t understand, from reading the post, how Dockhead could possibly know his Dad had one the same. Presume he knows your boat or perhaps his dad owned your boat at one time.

Perkins have made a heap of different engines over the years and where the boat was built will also have had an impact of the choices of motor available. They often had different models/options for different geographic markets. And many motors were sold for rebranding by the likes of Ford and Mazda and Nissan etc. After Perkins bought Gardner in the mid eighties weren’t some of the small Gardner diesels rebranded as Perkins?

Personally I would lend far more credibility to the owner’s manual of the specific motor I have in my boat than what some faceless pseudonym writes on a forum () Second in credibility would be the mechanic that has worked on my motor on a regular basis for the last several years. Maybe there are some scientific evidence based studies/trials that you might look up.

Obviously you want your motor to last as long as possible and perform to its best at all times. So given the seriousness of the question is this the right place to ask that question?

But there are a few general good practices for a diesel:

As much as possible, when you run the motor get it to operating temperature before turning it off. Just running the motor to get in and out of the marina is not good practice.
Get it warmed up before selecting high revs. The first thing I do when I get to my boat is turn the motor on. That way by the time I get all the sails organised etc, and get the boat ready to leave, the motor is warm and running sweetly.
And I very much agree with A64pilot’s advice: let it idle for a few minutes before you turn it off. Again I leave it idling whilst I put everything away, always takes at least 5 minutes.
And of course do the maintenance: change oil, filters, zincs, impellers etc regularly.
And you’ll have worked out by now that when I give advice it’s the best and right advice because I am bloody perfect!
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Old 30-06-2016, 14:20   #11
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Re: Running my engine hard?

Diesels prefer to be run under load. This means load at operating temperature. It does not mean thrashing it.

1900 rpm for a Perkins would be a reasonable loaded rpm. Minimum (in terms of the brake specific power curve) rpm will also optimize your fuel burn in most cases.

You want to avoid lugging, high load at low rpm, high rpm with low load or low load low rpm or extended periods of idling.

You will find there is an rpm range that will have good fuel burn, acceptable noise, vibration and adequate speed. This sweet spot will be unique to your boat. (Probably 50 - 80% of max rpm) For our Liberty 458 and Perkins 4-236 that sweet spot is 1600 to 1800 rpm. There is no single magic measure that will tell you exactly what the best rpm is.

Technically when an engine is at operating temperature all components should be at their designed clearance, size and shape thereby maximizing its useful life.

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Old 30-06-2016, 14:25   #12
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Re: Running my engine hard?

How hard a diesel is running is a function of the rate of fuel being consumed compared to maximum fuel rate, not relative RPM. For instance, my JD 4045 NA engine has maximum consumption of 4 gph at WOT of 2400 rpm. At 2200 rpm (just 200 less than WOT, the engine is working at 73 percent capacity.

Engines have "M" ratings which indicate the maximum percent of time they can be run hard.
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Old 30-06-2016, 14:36   #13
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Re: Running my engine hard?

The PO's Perkins probably predates M ratings. M ratings also assume an as new engine in a standard tested configuration.

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Old 30-06-2016, 17:24   #14
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Re: Running my engine hard?

Ha, funny, informative read...thank you and all for you advice/input. Regarding my engine...it ha blue one. Guess I have a lot of reading etc. to do!

Cheers all.
Mark
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Old 30-06-2016, 18:40   #15
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Re: Running my engine hard?

Quote:
Originally Posted by leftbrainstuff View Post
The PO's Perkins probably predates M ratings. M ratings also assume an as new engine in a standard tested configuration.
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The old Perkins 107, 108 etc have limits. Hardly anyone can reach them in a boat. Very few boats can get one of these engines up to even 36 HP. Never mind 45 or 50 hp. So if there is a limit based on RPM you will never reach it in most boats. I only get 2500 or so at full speed in our boat and 36hp is more like 3500. How you could get 50 is beyond me. The limits are max rpm for a short time then back to cruise. There should be a torque meter or something to be more suitable for sailboats.
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