Do you "Race" your Yanmar 3YM30 ?

[PKFK]

Hi -

According to the Yanmar manual, prior to shutdown you are supposed to "Race" the engine:

[FONT=Arial,Bold][FONT=Arial,Bold]

Note: Racing the Engine
With the clutch in NEUTRAL, accelerate from
the low speed position to the high speed position
and repeat this process about 5 times.
This is done to clean out carbon from the
cylinders and the fuel injection valve. Neglecting
to race the engine will result in poor​

exhaust color and reduce engine performance

I have never actually seen anyone do this, and have never heard of this practice before. Yanmar recommends doing this if running at slow speed (every couple hours), as well as part of the shutdown procedure.

Do you guys do this ? Comments or thoughts ?

Paul

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[Benny17441]

Do it all the time but only about 3 times. Diesel engines get hot after operating under load. Once you dock let the engine idle for a few minutes so that it can cool down; then run it up 2,3 or 5 times and pull the stop lever. Once the engine dies wait for the buzzer and turn the key off. It is my way of testing the oil pressure sender.

 

[Scott T-Bird]

No, the manual for my 2YM15 says nothing about racing the engine before shutting down. It says merely to run at idle until it cools down. I thought I checked that out pretty thoroughly earlier this year. I am going to check again.

I just looked at the operation manual I found on-line and it does say to race the engine on shut down as you describe. I don't recognize this from my manuals, but I have the installation manual and service manual, so this is very interesting to me ... and I will have to check it out with my manuals. Thanks for the heads-up!

It also says not to run it at idle excessively when starting up ... just start it and go. I used to run my 1GM for about 3 to 5 minutes to get it running smoothly enough to idle out of the slip.

 

[Ted]

Race your Yanmar

After a 5 minute cool down period at 1000 rpms, I always race my Yanmar 2GM prior to shut down. This is what's stated in the Yanmar Owner's Manual. The thinking is that all the diesel fuel will be completely combusted as the engine makes additional revolutions before it stops spinning. This prevents any unburnt fuel from making its way past the rings and into the oil pan when sitting for long periods of time.

 

[vmaks]

Do you think the "race" concept is true with all diesels.....Universal as well? My manual and a diesel bible I pulled off the net just indicates that you should run your engine at 3/4 throttle for at least 10 minutes on a regular basis and upon shut down just let it idle to cool down for 60 seconds. Never heard of the racing thing for 3-5 times. I certainly can adopt that habit if I am sure it will keep me from having diesel issues.

 

[Benny17441]

Diesels like to run hot as they burn fuel better. During the cool down period at idle they build up carbon as a result of a less complete combustion. Running up the engine in neutral before shut down helps get rid of that carbon. All diesels will benefit from the practice.

 

[Patrick S/V Shangra-La]

I run mine at about 1800 rpm for about 1 minute then shut it down while it is at 1800. This is the recommendation in the Yanmar manual.

 

[sea_casper]

With my single lever control, it is impossible to "race" my 3YM30 without engaging forward or reverse gear.

 

[Jake N Eggs]

With my single lever control, it is impossible to "race" my 3YM30 without engaging forward or reverse gear.

Sea_casper, if you press on the black rubber at the base of the control lever while you are in neutral and push the lever forward the engine will accelerate without engaging the transmission. The button is a transmission disengage. You will not be able to depress it while in gear. When you pull the lever back to neutral the transmission control will reengage.

 

[Steve Dion]

1. Ted's method is what I have understood to be correct. Let it cool down at idle speed for 5 minutes, rev the engine to 2000 rpm+/- and pull the engine kill cable/switch.

2. If you check out Yanmar Help they claim that you should run your engine at high RPM for every hour that you run it without a load (ie: charging batteries at anchor). So if you are charging your batteries for an hour, you should be running it up under a load for an hour to prevent carbon/coking.

I don't believe that reving it just before shut down is going to make any difference in preventing carbon.

http://www.yanmarhelp.com/index.htm (better explained here)

 

[Steve Dion]

With my single lever control, it is impossible to "race" my 3YM30 without engaging forward or reverse gear.

Maybe you have something wrong with your shifter. They normally have a neutral button on the shifter.

 

[Big Windy]

A mechanic told me to pretend my boat was a cruiser one day a month...take it out and run it hard, that way you don't have the excess carbon, etc build up. Diesels like to work, so work them, then prior to shut down let them idle for a few minutes.