SeaKnots

Best way to prevent the engine block from vibrating

I have a friend who has replaced the engine with a new one. The engine has been shaking since. He has replaced the engine mounts and new brackets, but that seems not to work. Given that the engine runs, and vibrations do occur, the person is out of options. During the engine replacement the mounts and brackets were replaced and refrabricated to compensate for any difference, but still the vibration is occuring to the point of concern? Too much vibration will cause friction against other lines and connections, as most sailors are aware of.  Any suggestion?

It does not happen when the vessal is in nuetral. Reverse is worse.

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Oh Man, I have had my woes with my significant other...my engine

 

I will be watching this post.

 

Also post this in group:

Zen and the art of sailboat maintenance

If the vibration happens only in gear, I would ck. the shaft alignment and cutless bearing.  You could disconnect the shaft from the transmission and see if you still have the vibration, try to eliminate various possibilities.
My friend has done so, and still it acts up, it's like the cam shaft is just heavy and it just does it. Its like the nature of the beast. We are going to be taking her out of the water soon, we are going to do trial and error and move the engine and propellor flanges until we find a happy medium. There is multiple positions, so wish us luck! :) This is looking more and more like a beer day!

If it runs rough while not in gear, it may not be running on all cylinders.  I'd check each cylinder by loosening the fuel line at each injector one at a time while it is running.  If air is in the system, it will get pushed out and when there is fuel flowing, tighten it back up and it should run fine. 

If when you loosen up the fuel line and it runs even rougher, that cylinder is running and move on to the next one.

He's got a racor filter, so all he has to do is pump that. Neg. on that situation.

Captn'

That is one of the things we plan on doing. Its got to be mounts or the brackets, something is not right. The engine should not be vibrating like it is. Like I stated, it's all rebuilt. A lot of work went into that vessel, it will end up being something odd, watch. I will keep everyone updated on the status. Friday is the day.

Captnron,

I will shoot for the cutlass bearing or the motor mounts that need to be tightened. It is new after all, I would bet things have just loosened up. 

Check the engines alignment.  It sounds as if its way off.

 

That is exactly what we will be doing this Friday. I get to hold station while re-adjustments are happening. It's got to be running, etc. to find the engines happy medium. When we redid the engine it had no immidiate after affects, this just recently started within 1-2 weeks later. We will eliminate the variables, from the shaft to the engine alignment.
it sounds like a fuel problem or if worst comes to worst, check the compression.

Hi Captn Steve,

Thank you for the advise, we will check everything out. It's been interesting to say the least. I wanted to learn, I am getting it, plenty of hands on training may I say! We will be checking everything out on Friday. I will keep everyone posted on what we find or the issue. Everything was calabrated, 1/2 the fuel connection work was completed by a lisenced machanic. Redoing the brackets, and the mounts was a job in-a-half; the alternator was the machanics job, we only could do only do so much at the time. Everything matched up perfect, now this started, so it boggles the mind. Unfortunitly, I think the fittings to the new mounts might not be tight enough and with the vibrations, it might have knocked everything out of alignment. I am not worried of the cam shaft, that was easy to align, but I do worry of the injector and the lines, but he would of smelled deisel, and this is not the case. If the engine is off-balance, we will just have to adjust that accordingly; this is were I love 2x4's and wieght displacement! We just have to check all engine functions, and eliminate the cause one by one. It will be something insignificant that causes an issue, as usually!  I am wondering now, mentioning about the altenator, I am wondering if possible if there was a wire that broke loose or something and touched engine parts? That could cause electrolysis to the surrounding metals, if different? In turn would were ware down  connections. One thing only needs to be loosened enough to cause the vibration to move the engine or weaken the brackets. 2 weeks in plenty time for that? Any suggestions on that aspect? 

The only way it could be the alternator is if there were and extremely heavy load on it, meaning your batteries charge level was very low.  If you have a shore power charger, this should not be the case.

As far as if a wire were broken on the alternator, there are only two.  One comes from the battery and acts as an exciter and the other one is the out put and also in some manner or another goes back to the battery.  Electrolysis takes quite a bit of time, and you would not see much of this in two months and certainly not enough to affect the engines performance.

I'd almost eliminate engine mounts unless something is physically loose.  I bought a rebuilt engine for my boat and the mechanics had it running as it set on blocks of wood and it ran very smoothly.

As I am reading through some of your comments, and just to clarify, does it run smooth while idling and rev'ed up but in neutral?  If this is the case you could very well have something around the prop that is causing an imbalance if you only notice this while in gear.  That could make a lot of sense seeing that your engine is new.

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