Race the engine for 5 mins. Does anyone do this?

Nomad Willy said:

Pmcsurf1,
Can’t read it w big i-pad too.
I assume you’re showing that Yanmar actually said that ... racing the engine.
What I said in post #7 did not include considerations for turbochargers. Sorry.
But what Yanmar said seems applicable to turbos. But I know little about turbos.
It would probably be good advice if one was to read it w/o the racing bit. Why couldn’t they just say something like “advance the throttle quickly to full throttle for two about one second and then back to idle five times” or whatever.

Edit;
I see Frosty wrote;
“ It sounds analogous to that quick "rev" that people of my parents' generation always did to their cars before shutting them off. You know, put it in Park, hit the accelerator and a quick "vrooom!" and then shut it off. Those were gas engines, but was there some basis for it?”

Perhaps people were thinking if an engine was “loaded up” (too much fuel) a blast of throttle would clear it out. Probably not. When the revs hit their high point .. if the ignition was turned off just then the high vacuum in the entire intake tract would suck in lots of raw gasoline. Not good. And while the engine was shut off the fuel on the cylinder walls could wash much of or most of the oil there-on. Not good.

I had totally forgotten about that Frosty.

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They did say rev 5 times and then let idle for five mins. Not shut it down immediately.

BruceK said:

Trouble comes from trawlers liking hull speeds and turbos needing to spool up and clean out. My mechanic says run the Cummins hard for 10 minutes before returning to the berth.

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I've heard the same.

boathealer said:

My cruising speed of 7kn is 70-75% of WOT. I don't do much else.

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That’s it w FD boats.
You’re running into the brick wall at about .8 knots below hull speed. Going faster is bordering on stupid. Going slower is like slower than the slow. Few skippers can handle that.
Our boat could make a run to SE Alaska .. about 1000 miles. We could probably do it by running 24-7 at night and all. But it would be safer to run at 5.5 knots and burn close to 1/2 gph less. We could easily make the run at 5.5 knots. But I don’t think I could stand running at that speed for 30 hours.

I’m different but in this respect I become quite normal.

So for FD boats you run at about a knot below hull speed ... and that’s it. Small FD boats are a one speed boat .. not technically but for all practical purposes they are.

SD boats are much much more popular. But do burn more fuel.


Pmcsurf1,
Yes not shut down immediately. Trawler diesels should be run near idle for several minutes prior to shut down. I think I said that before (this thread) but wasn’t considering turbos. I did that in all the truck driving I did.

The manual for my 315hp 6lpa stp yanmar reads exactly the same. I have concluded that they mean to “blip” the motor to full revs and back 5 times. I do it, in neutral, before entering the marina after putting lines and fenders out. I am pretty sure my neighbours appreciate it and i don't feel such a goose doing it in the marina. I am sure the engineers at Yanmar know a wee bit about their motors. Its a sweet motor but ridiculously large for my little 35 footer. I calculate hull speed at about 7.5 knots.

"I am sure the engineers at Yanmar know a wee bit about their motors."

No doubt they can explain everything in their native tongue.

Its the English translation that might be the worry.

Think there are competing needs. You want the turbo to cool down as much as possible before the engine stops but remain lubricated during that process. You want carbon to be burnt off before shut down.
The vrooms are brief enough they won’t much effect temperatures during the 5 minute shut down. My understanding is that when operating near WOT under load you burn off carbon deposits. Hence the need to do that if run at low speed, rpm and load for any length of time. I think it doesn’t much matter when you do that as long as it’s done frequently enough to prevent build up of deposits.
I’ve also been taught it’s good practice to vary your rpms a bit. Of course this is most important to a new engine but also not a bad idea with one with hours on it. Most boats have sweet spots. You know how many rpms to get to 1.1 s/l or hull speed. You know how many to get on plane. So you tend to run at several fixed rpms. Never really understood this as continuous duty engines in various applications (marine and otherwise) are run at fixed rpms their whole service lives without detriment.

FF said:

"I am sure the engineers at Yanmar know a wee bit about their motors."

No doubt they can explain everything in their native tongue.

Its the English translation that might be the worry.

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Lost in translation. Lol

Fa ra ra ra ra ra ra ra ra

MurrayM said:

Me-thinks that's the important bit.

I don't think they are talking about when you are running your boat normally...they are talking about when you are operating at a very slow speed, like trolling for salmon, or if you are charging your batteries at anchor at (or near) idle.

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That's the key here, running at slow speeds all the time or for very long periods (over several hours at a time according to the mechanic I have trusted for years) is NOT what a turbo was designed to do. Running the engine up under load to 80% load for 20 minutes or so every few hours to burn off deposits as a routine way to run these engines seems like whistling past the graveyard in an effort to fool the engine that it was run "normally" all day, but apparently is accepted as one antidote to non-boosted running. I know some run these Yanmars (my own is a 315 HP turbo'd 6LPA-STP, 3800 RPM WOT) lightly loaded all the time and say all is well, but where are these owners a number of owner turnovers later when the engines need turbos replaced prematurely? For those running out at speed to fishing grounds and low then RPMs for all day with running up to around 80% load for 20 minutes or so every few hours and lastly running at a good load all the way home, none of this idle revving should be necessary. I think Mainship elected to include turbo'd Yanmar engines in their "trawler" designs was so that their marketeers could advertise the concept of being able to run the boats at "high cruise," but the reality of the high fuel usage hits the pocketbook of people who actually prefer to go slowly too hard or their operating areas just preclude speedy (wakey) operation. In a vessel designed as a recreational trawler, they just seem to be the wrong type engines for which all these accommodations must be made.

There are two different issues here:

Carbon accumulation - this comes from running the engine too cool. At what RPM does your engine gauge reach 170F+ ? Try to always run above that speed and you'll have very little carbon problem. The people who get in trouble spend lots of time at 1400 rpm or below. I've got 2300 hours on my Yanmar 4JH4. 90% is at 2100rpm (3100 max so 67%). I do go to full throttle about once a week for 5 minutes to make sure it still doesn't smoke and that it doesn't start to overheat (which would indicate problems in the cooling system or exhaust elbow.

If you have two engines and you can maintain a straight course, you can do this one engine at a time while reducing the rpm in the other engine. This reduces fuel burn and noise.

Turbocharger - if you have a turbo before shutdown it's a good idea to blow any accumulated crap out. I was taught at a Yanmar Boat Owners diesel seminar to advance the throttle three times to the stops in neutral (Vroom, Vroom, Vroom). Then idle a minute and shutdown.

I had the same boat and engine for 13 years. I ran at 1800 RPM as well for 90% of the time. When I contacted a Yanmar rep about this, the answer was "slow speed" meant idling, or slow trolling and had nothing to do with how I was operating my boat. At 1800 RPM the load was sufficient to bring the engine up to proper operating temperature, turbo was doing what it's supposed to do, and the boat ran smoke free.

After 13 years the boat still ran great and didn't exhibit any problems. I don't think this manual notice about racing applies to you as well.

The key is just do what the manual says, the rest are just someone’s assumptions be they guided by experience or not. Actually anyone on here has less experience than the manufacturer, and they being conservative, usually provide a level of “over maintenance”. Personally have had two boats with Yanmar engines and both included the recommendation to race. It’s not that hard.

We have an Yanmar 380 Turbo (6YL3- UTP) and the engine surveyor when we purchased the boat in 2015 and Yanmar techs that have serviced the engine all say to periodically run the engine at 80% or more throttle when traveling. As we travel from VA to FL and during trips in and around FL we run at 80% to full throttle for about 5 minutes every 90 to 120 minutes. When we dock we run the engine for about five to seven minutes after the first lines are secure. This allows for a cool down period. This keeps the engine and turbo clear. We've never had an engine problem but we are also maintenance sticklers.

Hi folks,
Just made a copy from a Yanmar manual. Here it is. Have fun with the interpretation. It seems to me this is not what most of you would ever do.

(7) When operating the engine at low
speed for long periods of time, race
the engine once every 2 hours.
Note: Racing the Engine
With the clutch in NEUTRAL, accelerate from
the low speed position to the high speed po-
sition and repeat this process about 5 times.
This is done to clean out carbon from the
cylinders and the fuel injection valve. Ne-
glecting to race the engine will result in poor
exhaust color and reduce engine perfor-
mance

(8) If possible, periodically operate the
engine at near maximum rpm.,
while underway. This will generate
higher exhaust temperatures,
which will help clean out hard car-
bon deposits, maintaining engine
performance and prolonging the
life of the engine

3.3.5 Engine shut-down
Stop the engine in accordance with the fol-
lowing procedures:
(1) Put the remote control handle in
NEUTRAL
(2) Be sure to race the engine before
shut-down. (See 3.3.4 (7))

(3) Cool down the engine at low speed
(approximately 1000 rpm) for about
5 minutes.
N
NNOTICE
NOTICE
Always remember to allow engine
to idle below 1000 rpm for five min-
utes prior to shut-down to remove
heat from major components.
Shutting down the engine suddenly
while operating at high speed will
cause the engine temperature to
rise quickly, causing deterioration
of the oil and sticking of parts.

Clear the engine before shut down

Low RPM running allows unburned fuel to form soot on the ring glands and combustion surfaces. Higher RPM’s create higher cylinder temperatures (not necessarily visible on your coolant temperature gauge) and also creates more active swirling and scrubbing action in the cylinders which dislodges the accumulated soot before it bakes on for good.

So, in the last couple of miles to your shutdown point, just run the RPM’s up to perhaps 3/4 full speed for 5 minutes should do it. And allow the engine to cool down before stopping it for the day.

Comodave said:

Personally I would just do what the owners manual says to do. They built the engine so they should be the experts on the engine.

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Intersting thing in the quote from the manual they don't give numbers for low or high speed. Reminds me of the dislamers they strew all thru most manuals. If anything goes wrong you:
Didn't run it a high speed long enough.
Ran it at high speed too long.
Didn't run it at high enough speed.
Ran it at too high a speed.
On and on.

Maybe I have a bad aditude but if you try to read and follow the instructions they are usually meaningless and or impossible to meet all the requirements.

Ever read a can of deck stain. There might be 10 days a year that were not too sunny or hot or cold or wet or dry for the rquired prep, application and drying time.

Sorry for not posting often, but I do read everything.... almost



I don't understand the implied fragility and vulnerability of marine diesels on internet forums, and the implied expectation that they will die quickly if such and such is not done.


My GPS says that my driving averages 50 km/hr. Yes, I do mat it to the floor occasionally, and hit 120 kph when I think no one is looking. My last VW TDI lasted 450,000 km before the body rotted out, which is 9,000 hours. I have rebuilt both VW and Yanmar diesels, and the Yanmar's construction makes the VW look like a toy. I bought my Yanmar with 2000 hours on the clock, and disassembled it completely, and found that all measurements were still within the original specifications, when I often read that a diesel with 2000 hours in a boat is a well-worn engine.



Why then are there no dire and complex warnings in the VW manual, and pages and pages of quotes and discussion in marine forums?


Please explain.

Today I ran in the gulf going from Naples to Marco Island. Yanmar 6LYA-STP 370hp. I ran 1800 rpm. 7.5 knots for almost 2 hours. No smoke. When i got to the inlet I ran 2800 rpms for about 10 mins maybe 9.5 knots. No smoke. Idle to anchorage 30 mins. No smoke. Rev'd engine 3 times to about 3000 rpm. No smoke.
If it ain't broke...
I guess I'll just keep doing what I'm doing.
Btw, bought the boat in Deltaville VA and drove it to St Augustine, 700 something miles. No tachometers but ran about 8 knots. No smoke however coming down i did not run up to 80 percent. No tachometers. I also didn't race it at the hook because I didn't hear bout this till recently.

Bacchus said:

I have been a believer than running up under load is better for an engine that unloaded but I'm no expert by any means.
I cringe when anyone runs an auto, truck outboard or inboard up to high rpm sitting still. I'm a believer in not idling long, start up, get underway and increase rpm as temp increases.
After running at 1800 rpms I do try to run our Yanmar 6LYA up to 2700 - 2800 rpm periodically even if for 15-20 mins.

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There's no harm in briefly running an engine at WOT in neutral, I do this often to determine the governed RPM, to then determine if it's under-propped and reaching that governed speed. While it may sound unpleasant, it's actually less stressful than doing so under load.

I must confess, I've never heard of routinely "racing" in neutral every 2 hrs. and before shutting down. I have, however, heard of and recommend loading an otherwise lightly loaded diesel engine for 10-15 minutes every four hours. "Loading" in my book is running at about 80%, no need to run at WOT, the goal is to heat up combustion chambers, valves, turbo, to dislodge carbon, and to heat the oil to prevent sludge and varnish accumulation, this can be achieved with a 70-80% load.

I only attempt to run my NA JD at WOT (2400) RPM for a few seconds under load only to test whether the fuel filter needs to be replaced.

following. My Yanmar is somewhat smaller (55hp, turbo). The owners manual calls for running to near full throttle for approx 15 min for every 6-8 hrs of lower speed revs. My engine does it, but the noises it makes.....we haven't been doing it all that often!

Thanks Guru for this very interesting link which I have saved and printed for future reference on the boat as well.

IMHO, the operating issue here is "When operating the engine at low speed for long periods of time, race the engine once every 2 hours." Low speed is 700-900 RPMs or when there is almost no torque.


Racing the engine WOT loaded for about 90 sec is all I occasionally have ever done after a long period of trawling.


What I do often is to run the Ford L 120 for about 90 seconds to cool it upon arrival at destination in hot weather. The point of the fast idle after stopping is to cool down the engine block.


YMMV

That sounds like a sensible approach. Congrats

Pmcsurf1 said:

Today I ran in the gulf going from Naples to Marco Island. Yanmar 6LYA-STP 370hp. I ran 1800 rpm. 7.5 knots for almost 2 hours. No smoke. When i got to the inlet I ran 2800 rpms for about 10 mins maybe 9.5 knots. No smoke. Idle to anchorage 30 mins. No smoke. Rev'd engine 3 times to about 3000 rpm. No smoke.
If it ain't broke...
I guess I'll just keep doing what I'm doing.
Btw, bought the boat in Deltaville VA and drove it to St Augustine, 700 something miles. No tachometers but ran about 8 knots. No smoke however coming down i did not run up to 80 percent. No tachometers. I also didn't race it at the hook because I didn't hear bout this till recently.

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That sounds like a sensible approach. Congrats- IMacss

Ski in NC said:

I would not put too much faith into that part of the manual. In my past engr career I wrote parts of manuals for various machinery (including large diesel gensets) and it was amazing how little oversight there was over what I wrote.......And then you have the Yanmar manual that was clearly translated from Japanese, and I have had many examples where I am an certain the translation was not well done....None of the ...guidelines are that important. I have been around many engines where the duty cycle was brutal, and the engines did fine. But if you can follow them, I think they are somewhat helpful.

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This I believe also. The Lehman 120 in my boat was still hardly using any oil when I sold it with over 4000 hrs on her, and all we (collective owners) ever did was run her at her sweet spot or thereabouts most of the time, then the idle down cooling was taken care off when anchoring or docking as a natural outcome of the slower speeds. No revving - ever..! Oil changed once a season - I used Magnatec Diesel all the time (16 years) I had her.

FF said:

"I am sure the engineers at Yanmar know a wee bit about their motors."
No doubt they can explain everything in their native tongue.
Its the English translation that might be the worry.

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That is one very correct statement, if ever there was one. Slight differences in nuance can add up to a lot in effect.

CarlF said:

There are two different issues here:
1. Carbon accumulation - this comes from running the engine too cool. At what RPM does your engine gauge reach 170F+ ? Try to always run above that speed and you'll have very little carbon problem.
2. Turbocharger - if you have a turbo before shutdown it's a good idea to blow any accumulated crap out. I was taught at a Yanmar Boat Owners diesel seminar to advance the throttle three times to the stops in neutral (Vroom, Vroom, Vroom). Then idle a minute and shutdown.

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1. Correct..!
2. Wrong, sorry...there is no crap in a turbocharger. It is spun up by exhaust gases and compresses the intake air - fuel addition comes after that. However, as FF pointed out, cooling the turbo down is important so you don't cook the oil in the bearings. However, water-cooled turbos largely avoid the need for an extended cool-down, so the natural cooling as one comes in to an anchorage or dock takes care of that also.

One thing I have learnt over the years of being a bit of a car and boat buff, is that many mechanics are often as full of old wives tales as your average man in the street. I happily exclude Mr D'Antonio from that generalisation, but I suspect he might agree.

One great example is the way so many mechanics (here in Oz anyway) condemn E10 fuel out of hand - "wouldn't touch the stuff" - "you'll never find it in my car", examples of their responses. Yet I have run E10 happily and without incident in several vehicles from a 1990 GT4 to my current new vehicle, and they have all run as sweetly as possible, with cleaner engine oil I'm convinced, as one other positive benefit besides the cost saving.

One suspects a lot of the confusion re even so-called 'official' manual recommendations about engines might suffer the same prejudices, as Ski intimated in his post. That's my take on it anyway.

Frosty said:

After reading the manual page here is what I think. However note I'm not a mechanic so just amateur thoughts.

They say NOT to shut down after a long/high speed run (i.e. no cool down).

What I have read here before, which makes sense to me, is that most of us will have run up to speed at some point during the day, but then do run at a reasonable length of time at low speed with almost no load (coming in to the marina or anchorage, maneuvering, etc.). That seems like it would take care of the "don't shut down immediately after high speed."

So that leaves the brief "race" before cool down and shutting off, which is your original question. They say it's to remove carbon deposits. So, if you had made a high speed run earlier, are there any to remove? Is this only for people who have trolled all day with no speed run?

It sounds analogous to that quick "rev" that people of my parents' generation always did to their cars before shutting them off. You know, put it in Park, hit the accelerator and a quick "vrooom!" and then shut it off. Those were gas engines, but was there some basis for it?

I guess at the end of this post, I have the same question as you. Is there a benefit to these quick "vrooms"? Do they need to be done if you had already run at high speed during that day (but then idled into the marina or anchorage). Is it a good idea, a neutral one, or a bad one?

(I don't see this as them recommending a long period of high RPM's. I interpret it as quick bursts a la the parents and the car.)

If it were my engine I would (in addition to posting here, which is a good idea) contact Yanmar and see if they can flesh it out a bit. Does it need to be done if you have already run at high speed? What are the downsides? Etc. I'd probably also call a trusted Yanmar mechanic to get their take. Wording my questions so as not to "lead" one way or another.

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All that 'goosing' of the gas engine did was squirt a jet of raw gas into the carburetor, through the accelerator pump, leading to raw gas washing down the oil on cylinder walls and early engine "ring jobs" on engines. Over rich fuel mixture coupled with such practices just wore the engines out. If you want to clean carbon deposits from your diesel have a look at Cost Effective Maintenance "FTC Decarbonizer" (https://costeffective.com.au/product/ftc-decarbonizer/). This cleared up any smoke in my Perkins T6-354, running smoother, better power.

Tiffany said:

All that 'goosing' of the gas engine did was squirt a jet of raw gas into the carburetor ... and early engine "ring jobs" on engines.

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Glad I never did that then, whew.

Growing up, we had "heard" of people turning over 100,000 miles but weren't sure if it was a rumor. And of course odometers mostly only went to 99,999. Maybe too many "vrooms" at shut down (mostly kidding; obvs there were numerous factors).

Thanks for the explanation.

Uggh... Except for the sea trial I've never run my engine WOT, or even up to max continuous revs. 3 min warm up and a gradual runup over 10 min or so, at cruise by about 150*. I never rev in neutral, except once in a while when I push the wrong lever.

That said, I do believe the manufacturer usually has the best advice for their product.