Diesel engine likes to run hard…

[Skylark]

I think a little credit to the engine maker is due, too.

Volvo, as an example, has a number of operating divisions: Car (pre-Ford), Truck, Construction Equipment and Marine. In many applications there is a common base engine platform across the range. However, each operating division has an engine engineering community. The reason is simply: to stop you from needless worry. It's their job to ensure that the engine operating duty cycle is matched against the application. Duty cycle is just another way of describing typical use. Clearly, a 40 tonne Truck engine lugging across Europe has a difference use characteristic compared to how I use my 2030.

Just apply common sense. Don't over-rev or over-load a cold engine. Don't shutdown a very hot engine. I don't personally like holding the same speed/load for extended periods. Treat it with TLC by keeping it bathed in quality, clean oil. Keep the inlet air filtered. If it's a calm day, 2000 rpm pushes her along nicely. If it's lumpy and I'd prefer to be tied alongside, I'm going to open her up a bit.

David

 

[Sailfree]

Yanmar's workshop manual for the 3GM suggests as follows:


When under way, periodically operate the engine at near maximum revs. Also intended to blow out carbon deposits and increase exhaust temperature.

The engine is designed for maximum throttle operation, 3600 - 3800 rpm, for less than 5% of the time.

It is designed for cruising speed, 3400 rpm, for less than 90% of the time.

On my 75HP Yanmar the reality is that if operated for longer than 20 mins in excess of 3200 revs the overheat alarm sounds. It cost me nearly a £1,000 checking out everything on a 5yr old engine to be advised that there is nothing wrong and high revs don't give much extra speed and should be considered "emergency" power only!

I had discovered that and rarely use more than 2500 but as a precaution now put a rev limit display label on for charterers!

 

[lw395]

Revs load and power are four different things

Wide open throttle? I thought we were talking about diesels.

Running at engine at high speed and low load is not the same as running it hard.
Some people believe that high cylinder pressures, (i.e. making the engine work hard) are the key to avoiding cylinder glazing. Not convinced myself. Good oil and accurate timing might have more to do with it?

Also it is said that running an engine at high speed with no load causes it to vibrate more intensely than if 'damped' by a load, so may do more damage, particularly on a 360degree twin or a 180 degree straight four. I don't know if that's really significant, but can understand that it might be...

Temperature is important, not too cool to burn properly and not too hot, running at high load for a long time may cause the oil temp to rise above what is best. Running too cool does not evaporate the water, so speeds corrosion and degradation of the oil. Too hot and the oil is thinner and if the engine is at max speed, various parts are trying hardest to break the oil film and wear each other out.

 

[vyv_cox]

Wide open throttle? I thought we were talking about diesels.

It's a direct quote from the Yanmar workshop manual. Personally, I don't see a problem with the phrase, although technically incorrect everybody understands what it means.

 

[lw395]

WOT?

It's a direct quote from the Yanmar workshop manual. Personally, I don't see a problem with the phrase, although technically incorrect everybody understands what it means.

Or at least they think they do?
To some it means max revs on the regulator, possibly very little fuel going in, to others it means max power on load, not necessarily at max revs. (particulary on a brake dyno)
Spinning a diesel fast is no way the same as working it hard.

My favourite japanese manual quote is 'steering handle pipe' for 'handlebar tube', I rank that with Benelli's 'your petrol may go sour'!

Cheers,

 

[Bosun Higgs]

For 2030 owners - I can reassure them that I've run mine at 2,700 rpm continuously for 24 hours without a problem.

careful with that. I ran a Yanmar 2gm for 36 hours at constant revs ( never touched the throttle) and ended up with polished bores so shiny you could see your face in them. It was a relatively new engine in good nick, and the jury is still out as to whether it was too good a modern oil the agent had put in or simply running it an at unaltering speed for so long. probably both - but it had to have a new block.

Its always best to vary engine speed a bit.

 

[richardbrennan]

I have a 2030 which is now 13 years old. This was an upgrade option on my boat, the standard engine being the 2020. I find I get around 6 knots at 2300-2500 rpm according to how clean the bottom is. Anything over this simply results in a considerably increased noise level and considerable wash. Occaisionally, such as when passing through the entances to Portsmouth and Poole at spring tides I have push it up to something over 3000 rpm and get over seven knots. The engine seems very happy, starts easily and does not emit anything nasty from the exhaust. I do not think you will have any problems operating as you do.

 

[Interlude]

The other piece of advice in the Yanmar manual is to let the engine idle for five minutes to cool down after normal running, then to take it up to full revs (with clutch disengaged) five times, to blow the carbon out of the exhaust ports. I seem to be the only person I know who does thus regularly, but my previous 1GM10 had a well blocked up exhaust port in the head and elbow, attributed by the local dealer to this not having been done. Fingers crossed for the new 3YM20.

 

[Avocet]

I must say I'm with Peter Gibbs here! We don't get this hung-up about our car engines! As other have said, there are a few stupid things that one shouldn't do, but as for the rest, it's all within the "envelope" of conditions under which the engine is intended to work and it's all fair game! Avocet's engine is old and some parts are now almost impossible to find. Added to that, it's raw water cooled so ultimately, it's going to need replacing anyway.