Yanmar 3YM30 Vibration

[svenskflicka]

Hello,

We have a yanmar 3ym30 with 2100 hours that seems to be vibrating (shaking) a bit too much at idle. Everything smooths out once you add a touch of throttle. I'll try to get a video next week, but does anyone know how much vibration would be 'normal'?

One other thing is when you press the 'stop' button the engine seems to turn off with a bit of a CLUNK.

[camkelly]

Yep, that sounds like a yanmar. I have a 30gm30f. Yanmar's mounting brackets don't seem to be very good. I had a mechanic look at my engine this year and we're going to replace the brackets with ones from a different manufacturer when I haul the boat this fall. I even had a yanmar dealer tell me to use different mounting brackets than yanmar's. What you described is what I experience on my Catalina 320. Next season my hope is that all that clunking goes away.

[Wotname]

Originally Posted by svenskflicka

Hello,

We have a yanmar 3ym30 with 2100 hours that seems to be vibrating (shaking) a bit too much at idle. Everything smooths out once you add a touch of throttle. I'll try to get a video next week, but does anyone know how much vibration would be 'normal'?

One other thing is when you press the 'stop' button the engine seems to turn off with a bit of a CLUNK.

How old are the engine mounts? If original, they will be past their use by date.

[svenskflicka]

Originally Posted by Wotname

How old are the engine mounts? If original, they will be past their use by date.

Unknown, so I have to assume original.

[Wotname]

I should have also asked - it this a new issue or has it been this way for some time or is the boat new to you?

[svenskflicka]

Originally Posted by Wotname

I should have also asked - it this a new issue or has it been this way for some time or is the boat new to you?

We thought it looked more than 'usual'. But this is our first year with the boat so we haven't spent THAT much time looking at the idling engine.

[Rapanui]

We have a 3ym30 and there is very little vibration at idle. There are 2 sides to vibration, the excitation which could be either out of balance
or uneven combustion and the response of the system which could be a resonance on the mounts.
I would check the idle speed (to low and you could excite the mounting resonance which should be at a lower frequency than that which occurs at idle). Then check the injectors are ok (spray pattern, leak by) which could cause imbalance in the firing. Of none of that works, then look at the mounts.

[kevincook]

I've had this problem when our old 3QM30 did not have the fuel lines bled properly after a filter change.

[svenskflicka]

Update:

We changed the air filter and fuel filters and did the Seafoam injector cleaning via "filter method" and there was no vibration at idle. Hopefully it's the same when we test with the engine not warmed up.

Two things we noticed:

1) The air intake has a very strange design. There is a cone shaped air filter, but air can only enter via a small maybe 1.5in tube that extends off the filter housing? Wht have this large filter that can only intake through a tiny portion?

2) The old filter was completely degraded where said tube intake is with supposedly 100 hours on it. We requested a full service when we bought the boat, but who knows if the actually did it.

[Compass790]

The filter setup is like that to lessen intake noise. I took our original one off on our YSM8 & replaced it with an aftermarket oiled foam filter as Yanmar prices are ridiculous here & I could notice no difference in noise levels with their air/cleaner silencer & the aftermarket one.
However it may be different on your 3ym30 as ours is a noisy single. Doesn't cost you a lot to try an aftermarket one tho.

[Rapanui]

It sounds like uneven combustion was the cause and the sea foam fixed it. If there is injector leak by or spray pattern irregularities you would expect that to be a cause. I use Marine 16 Complete to regularly dose the fuel which is a combined fuel system cleaner and diesel bug treatment and preventer. Additives definitely work, when I periodically use Redex Diesel fuel treatment in the car you see a measurable improvement in fuel consumption.

[davefromoregon]

Is this likely to be the case if there is a lot of vibration at 2100 rpm? I’m not seeing an unreasonable amount below that.

[Phyrcooler]

Originally Posted by davefromoregon

Is this likely to be the case if there is a lot of vibration at 2100 rpm? I’m not seeing an unreasonable amount below that.

Many engines have an RPM they don’t like. I use that term loosely, and I am not an engineer. But I do know that my engine/Saildrive has a vibration at a certain mid-level RPM (I don’t remember exact number - somewhere between 2100 - 2300.). I just feel it and bump the throttle up or down a tad depending on my needs, and everything smooths out. I’ve also noticed the same in aircraft engines.

[Rockinar]

I have a Westerbeke 30B THREE and it vibrates pretty good. Was told 3 cylinder vibrate more than 2 cylinder. I got new mounts and it did not seem to make any difference. Engine only has about 2400 on it, but it just seems old and noisy and tired. Thinking of repowering just to have the reliability of a new engine and transmission, and hopefully less noise and vibration.