Yep, another query..on a Yanmar 2GMF..engine clatter

[SeanP]

Yanmar buffs, an appeal for your advice....

We took her out yesterday for a sail. While underway we smelled a pungent smell of diesel. When we anchored shortly thereafter and I removed the engine hatch I saw a fair bit of diesel in the engine bilge (see image attached). I have taken her out twice before and she never had diesel in the bilge. As we neared our bay I fired up the engine and dropped the sails. It was pretty breezy so I had the RPM up at around 2000. The motor began to clatter loudly and the entire boat shook. I eased the throttle back down to where the vibration clatter was less and eased into our bay. Once I tied her off and killed the engine, I opened the engine hatch and saw this "C" shaped circlip lying below the motor in the bilge (see image attached).

Any ideas on the leak and what the circlip may be? And why she would shake so harshly even at 1500 RPM?

Cheers,

Sean

 

[jssailem]

Sean,

1. Just a SWAG, but I think you have a fuel leak from the fuel line system that is weeping fuel. This may or may not be associated with your RPM issue. (If there is a leak and air gets sucked into the fuel line it could contribute to rough engine operation).
2. Secondly, it looks like a circlip fitting has sprung loose. On close examination it may not be a circlip it may be a gasket that has broken in half.

Look at the engine and trace the fuel leak. It looks to be enough fuel to leave a trail on the engine or the hoses.

Oh and Welcome to the forum. We need more folks participating here in Oregon.

 

[SeanP]

Hey John,

Thanks for the feedback, much appreciated. I will check it out...I believe you are right the it is a broken gasket. The air in the system would explain why it ran so ragged for sure! Time to break out the guide on how to bleed the system, right?

Cheers,
Sean.

 

[jssailem]

Time to break out the guide on how to bleed the system, right?

Sean. I'd be looking for the leak first. Clean - dry rag the engine so you can see the leak or it's trail.
If you try to start the engine and it just cranks then yes you may have air that has leaked into the fuel lines. Then you will need the info on bleeding the fuel system. Not sure, do you have an electric fuel pump. If so you may luck out and not need to bleed the fuel lines, just find the leak.

You might also take a look at the fuel filter (assuming it has a clear bowl). Air sometimes shows up as bubbles.

If you find the engine started then you just might see the leak (say a loose fuel joint fitting) or the seeping fuel.

The amount of fuel leads me to believe it is a trickle not a gusher. You might place a dry clean diesel absorption pad under the engine. It may give you clues that will lead you to the area of the engine that needs your attention. (Like putting a piece of cardboard under an old car to see where it is leaking oil. )

 

[SeanP]

Hi John,

She does start yes and yes have an electric fuel pump. Will see if I can track down where it is weeping from. Guessing that due to her running so ragged there may well be air in the system though. Open to more feedback always

Cheers
Sean

 

[jssailem]

Good news. The electric pump will solve the bleeding issue once you resolve the location of the dripping fuel.

 

[SeanP]

Spoke to mechanic who may have time to check it out Friday. He reckons the shaking may be due to transmission or drive shaft issues and believes the fuel leak is separate from the shuddering. More to come...

 

[Benny17441]

Beware of the Ace mechanic that can diagnose a drive train shudder from a mere conversation. A fuel leak when the engine is running is consistent with an air leak in the other direction when the engine is stopped and an air leak can produce the symptoms of rough running you describe. Don't know what engine you have but some like the 2GM20 are hard to bleed, meaning it takes multiple tries to dislodge all the trapped air. Make sure the fuel leak is fixed and the engine is running fine in neutral before touching the drive train.

 

[SeanP]

Roger that Benny! Thanks...will circle back to report out how things go....

 

[Unwrittentimeline]

Have you gotten a better look at the issue? I'd have to agree with the above that a fuel leak that is also letting in air seems the most plausible issue from what you describe. If you have the same rough running issues in neutral at RPM as in gear it is not likely a drive train problem. Bleeding the 2GM is fairly straight forward and if you want to give it a go yourself I have a video working through the fuel bleeding. The bleed starts at 07:25.

Hope it works out for you.

Dave

 

[Dan Hill]

I would take a closer look at the injector lines. If you have a leak in one line it can cause a severe shudder that's more noticed with higher revs. The injectors need a certain psi to fire properly, if low you will get a misfire that will cause an imbalance.

My 2c
Dan

 

[SeanP]

Thank you Dan and Dave, very helpful. I will be heading down there to check her out in a few and will report back what I manage to discover. Sean

 

[SeanP]

Morning all, collective insights requested

1. So, the fuel is leaking from what appears to be the transmission/motor seam (see image). I have also linked to a short clip showing the drip. I also link to two further short clips; the first is the motor running with forward transmission engaged and motor at about 1500 RPM. The engine is hopping about quite a bit. The second clip shows the transmission shaft whipping about too.

Any thoughts are welcome. Thanks, Sean

 

[Unwrittentimeline]

Sean, I couldn't open the video files so I don't have another solution for the rough engine other than a fuel leak that is allowing air to get into the system. I say this since you have an accompanying fuel leak. If it is not an air leak, it could be any number of items from easily fixable (dirty injector, dirty fuel, etc.) to something more sever from (bad compression seals, worn main bearing, piston pin, loose flywheel, etc.).

I seriously doubt that you have a fuel leak from the engine/transmission connection. There are no fuel lines between these parts. The only real way to get fuel into there is if you blew a hole from the engine cylinder to the transmission mount. This would be a significant emotional event if it happened. The drip you are seeing is probably from somewhere much further on top of the engine. Likely dripping from a fuel feeder line or the return line. It then seeps down to the lowest point and drips off the engine where you see it. Fuel is hard to track on an engine in a dimly lit sailboat engine compartment.

Good luck finding it.

Dave

 

[SeanP]

Hi Dave,

Agree, I cannot get my head in far enough to see over the rear of engine to see where it might be coming from and then leaking down to that point. I suspect the leak is separate from the motor vibration.

The video links are:
https://www.dropbox.com/s/ydjgzhrkea39wxh/IMG_4137.MOV?dl=0
and
https://www.dropbox.com/s/lit9zejrl4nngfw/IMG_4136.MOV?dl=0
and the leak one: https://www.dropbox.com/s/g7inte490o1ohaf/IMG_4135.MOV?dl=0

 

[Ken13559]

Looks like a nut to the right side of photo is coming loose.

 

[SeanP]

Looks like a nut to the right side of photo is coming loose.

Thanks Ken, will check that too! Sean

 

[nveater]

It appears from the video that fuel is running down the engine to the low part of the engine where we see the drips. I would look at the fuel line as it runs from the primary filter to the lift pump to the secondary filter and finally to the fuel injector pump.The fuel leaks I have had on my yanmar have been between the lift pump and the secondary or engine mounted filter. Use a paper towel and wrap around each section and perhaps you'll find the fitting that's loose. Sometimes a gentle snugging with the wrench will help or you may have to replace the copper washers at some of the banjo fittings good look

 

[SeanP]

It appears from the video that fuel is running down the engine to the low part of the engine where we see the drips. I would look at the fuel line as it runs from the primary filter to the lift pump to the secondary filter and finally to the fuel injector pump.T

You are dead right! I flipped the crush washer over on the lift pump and the leak stopped! However...and this is the mystery part......when I started it up on Wed with the mechanic present, there was ZERO vibration. We surmised that a plastic bag or something must have been wrapped around the prop. I dove on the boat to inspect the prop and shaft...all clear, snug, and secure.

On Saturday I took her out for a sail. I motored smoothly out and then raised sail and cut the motor. After sailing for the afternoon, I started her up to head into our bay. Vibration was BACK. Any ideas on what possibly might be causing this weird phenomenon? Cheers, Sean

 

[nveater]

Sean- I assume you have checked your shaft alignment- is the vibration at a certain rpm range ? I get a vibration between 24-2600 on my engine- not bad but noticeable from other rpm ranges. Do you have a folding or feathering prop that perhaps is not fully deploying. Or I guess a fixed prop could be unbalanced but I am only taking a SWAG here- I am not a very good diagnostician but those would be my thoughts-