So I have a 23 hp Yanmar diesel engine. I am told that a cylinder drop's out. Then it drops back in. What does that mean?

It makes a funny rattling type noise at lower engine speeds. As the speed increase's noise goes away.

Mechanic also said it could be an injector?

Any thoughts or advice. What am I looking at?

Thanks guys.

I'd wager it's the injector "dropping out" by not injecting the fuel.

Now whether it's a mechanical or electrical issue I couldn't guess...

That’s a mechanical diesel. Once it starts it simply needs air, fuel, and compression. Is there any smoke, especially when the cylinder drops out? If so, what color? He’s saying the cylinder stops firing. It could be several different things, needs valve adjustment, bad fuel injector, issues with the valves, or worst case scenario a broken ring. What has he done to determine it’s an injector?

I am not real sure to be honest. Some smoke. I would say more blue than grey. Not a lot but some.

I just dropped off to the mechanic so will be a few days before I get any info. from him.

I would go with an injector being at fault. The fact that it jumps in and out pretty much eliminates the other things mentioned.

Jim

I would have ran a tank of fuel with Lucas injector cleaner through it first I think.

That engine is not a common rail engine, IIRC. The problem is just as likely to be in the injection pump as in a fuel nozzle.

Yeah, first guess is a weak injector. Those are pretty rugged little engines. I have an old JD950 w/ a 3cyl Yanmar. Knocks like crazy at idle, but smooths out.
And when “they” set off a dirty EMP bomb, I’ll still have transportation.

Pardon me, I'm just curious.

Are those cylinders sleeved? Easily replaceable?

Thanks.
.

If an ejector is going bad...sometimes it "sprays"...and ignites...and some times is "squirts" a jet and onset ignite.

A sticky injector can cause the rattling you describe...and the spray/squirt I mention above.

Could be the injector pump too.
I hope it's an injector...

Thank you guys for the thoughts. Probably get word next week on what the cause is. Hope it is a lesser cost fix. Fingers crossed. Thanks again. I will report back once I know.

Do you use any fuel additive?

My understanding is that the low sulfur diesel doesn’t lubricate the injectors as it used to do before they removed the sulfur. This is important as injectors are very precise assemblies. And not cheap.

I use a fuel additive all year in both diesels (Cummins & Yanmar). Definitely run better, smoother.

I use Power Service Diesel Fuel Supplement. I am sure there are other brands available and maybe some better.