idling revs on a Yanmar 4JH4E?

Ian_Edwards

Ian_Edwards

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I'd like to check the idling (tick-over) revs on my Yanmar 4JH4E.

I've looked in both the operator's manual and the full service manual and can't find it.

It seems daft to be asking such a simple question, the Yanmar manual are very comprehensive, perhaps I'm not looking in the right place?
 
The published power curve for this engine tails off at ~ 1200rpm, at which point the shaft output to the prop is below 4kW. For all practical purposes this is the idling RPM.


Just found another curve here http://www.zrd.com/pd/4jh4e.pdf

This tails off at around 1600, but at a higher shaft power.
 
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Topcat47 said:
This tails off at around 1600, but at a higher shaft power.
Click to expand...

It tails off only because there are no measurements below 1600rpm, an absurd level for tickover rpm.

It's a straight four, so probably not very different from our Beta 50, which the manual gives as 850rpm. If it's a bit lumpy at that, give it another 50rpm.

Or, better still, hope someone comes along with a figure Yanmar condescend to divulge, but in the meantime my suggestion will do no harm.
 
Mine is currently idling at 714 rpm as measure by an optical taco and a white tab on the crank shaft pull. It's quite smooth at that and the gears engage without any audible cluck, the revs don't drop when forward or reverse are engaged. But I'd like to increase the idle revs a little so that the alternator kicks in at tick over.
I was just wondering what the Yanmar recommended rpm was.
It doesn't look like it's published.
I'll probable increase it a little and see what effect it has on boat handling at low speed.
 
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The quoted idling speed for my 4JH4AE is in the range 775-825. Mine was set at 800 rpm but haven't checked it for years and VDO display isn't really accurate enough at that level.

I got the figures from a Yanmar datasheet but I only saved it as "4JH4AE.pdf" so don't know Yanmar's filename. It was 4th Edition of something or other and published in March, 2007.

Only thing the Service manual says is "NEVER attempt to adjust the low or high idle speed limit screw." and general comments about "idle speed", no specific rpm as you already discovered.
 
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Ian_Edwards said:
But I'd like to increase the idle revs a little so that the alternator kicks in at tick over.
I was just wondering what the Yanmar recommended rpm was.
It doesn't look like it's published.
I'll probable increase it a little and see what effect it has on boat handling at low speed.
Click to expand...
can't you use the throttle?
 
Ian_Edwards said:
I'd like to check the idling (tick-over) revs on my Yanmar 4JH4E.

I've looked in both the operator's manual and the full service manual and can't find it.

It seems daft to be asking such a simple question, the Yanmar manual are very comprehensive, perhaps I'm not looking in the right place?
Click to expand...

Hi.
I have just found this link which states the idling rpm. Took a while to find.
http://wodawiatrimy.home.pl/data/documents/yanmar_1.pdf
 
The idling answer are correct it’s around the 750rpm mark.

For charging - no chance at this speed. Most standard alternator installations on these engines don’t start exciting until you get up around 1000-1200rpm - you should see this effect on your meter. And if you’ve got a 2nd auxiliary alternator fitted then that might be even higher - I had a large 2nd Balmar for my house batts on my previous 4JH4E and that wouldn’t start charging at full noise until 1300-1400rpm.
 
Thanks for the reply, I got the idling speed sorted a while ago so the alternator just kicks in on tickover, and more recently reduced the pitch of the MAX Prop' by one notch, which reduced the boat speed on tickover a little and allowed the engine to reach it's rated rpm in flat water. The boat still reaches over 2 knots on tick over, but I've learnt to live with that.
 
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