If I was local I would use my reed tachometer to try to establish the frequency of the vibration. This could help find the cause. Does it vibrate the same amount through the rev range? Can you get access to the drive components to put your hand on them or touch with a screwdriver to the ear to get some clues?

Shaft out of alignment??

Thanks, Yes it could be any number, just a bit Pi....off that all, weeks of waiting.....and now..............

You still have it Steve!! The one thing you did not mention above is engine mounts. You have checked those haven't you???

All engines will vibrate to a certain degree and they all seem to have their "sweet spot" and their "sour spot".

Is it really that bad???

When the shipwright and marine mechanic had done their work, did they go for a sea or basin trial with you?? That is what a marine mechanic should do to check the operation under working conditions.

Engine mount coupling alignment ... after replacing all what you have its up to engine alignment .....try running the engine in gear and watch the coupling and bearing?

Do you have a shaft anode and is it still firmly attached?

Hi Lexmark, I know exactly how you must be feeling, i have done all that you have, Had the shaft balanced, the Prop balanced , New bearings, etc etc all of which costs $$ I have just recently replaced the four Engine mounts, and have at least moved the vibration, what i mean is used to vibrate badly at and around 2000 revs which is were the motor seems to like working at, it now vibrated at 1200 revs and i have been out a couple of times after adjusting the screw engine mounts and each time it is slowly getting better and better, but the encouraging thing it that i now know im heading in the right direction. So persevere, im sure you will find and fix the vibration, Ben

I installed two Volvo 2003 engines in my Martzcraft 35, both times there was excess vibration.

After first engine installation I didnt know the cause. Because I was on limited budget I decided to try and fix myself. I undid the shaft to engine coupling and sticky taped a stick from the side of the boat and positioned its end about 2mm from the coupling.

The purpose of this was so I could easily see if the coupling moved up and down as it rotated by sighting the distance moved from the coupling to the end of the stick. Purely a visual reference.

The gear box side didn't move as that side of the coupling was turned by hand. Turning it 360 degrees and its circumference was always 2mm from the end of the stick. The prop shaft one did move. 1mm distance on one side and 2mm on the other. Bing! it was a bent propellor shaft. A contractor looked at straightening it but for the sake of $600 I bought a new one.

After it was installed the prop shaft rotated perfectly. After bolting it to the engine (gearbox) it was fine.

That "reconditioned" engine was a dud, painted green by a shark who told me it was reconditioned. When I took it back to where I bought it the service guy didn't know I had bought it from them and told me the engine was cactus!! That's a different story. I met someone who sued them for a $20K engine, same story, but mine was only $3K and they denied everything so I blew $3K.

Second engine: Installed it, connected it to the perfect prop shaft and there was a very annoying vibration. Got my stick out and did the same thing as with engine #1 before. I could see the shaft-engine coupling rising and falling 2 mm or so. After a very long time spent adjusting the engine mounts up and down I got it to rotate with no movement. Bing! Vibration gone.

If I ever did it again I think a strobe would be the way to go. But the stick was cheaper and didnt need batteries.

Lex, you did not say if the motor mounts had been replaced in your upgrade, or even adjusted?

The problem usually comes down to a hammer. I have watched "experts" remove props and flanges by tapping with a hammer. 3 inch shafts are easily bent like this. Toy sized shafts in yachts more so. Interestingly straightening shafts is not that hard or expensive and is done with a clever bloke and a hammer!

SandS said..

exactly , but shouldn't these pro experts have a you buet prop puller ?

the industry is full of this sheelbe right ,roughenough is good enough attitude . or is it they just don't know the correct way ,or tool to use ?

I used to work with a guy in a mine ,I called "Tapper" if it would not work he would hit it

Lexmark said..
Hi to All

I think that the problem has been solved, well not sure as yet, but now the area has been moved to the "Thing" between the gear box and the motor, it has springs, so they are saying that they are either broken !!!!!!!!!!!!!!!!!!!!
Ok so now just to get a new one.....OK its late friday...Sat...Sun...Public holiday !!!!!!!!!!!!!!!!!!!!
Am starting to think that I may need to register here to vote.....been here that long.........But still a nice place

the rates are due as well Lexmark plus power and water

cisco said..

Ramona said..
The problem usually comes down to a hammer. I have watched "experts" remove props and flanges by tapping with a hammer. 3 inch shafts are easily bent like this. Toy sized shafts in yachts more so. Interestingly straightening shafts is not that hard or expensive and is done with a clever bloke and a hammer!

What???............A hammer to phuck it and a hammer to phix it. The unclever one first and the clever one after.

But yes, you are right. Given the cost of prop shafts, if yours is bent it is worth getting someone clever on the job with the right kind of hammer. A dead blow hammer would have to be the go.

My prop shaft is quite long, about 2.5 metres, and 1" dia. I got a new one for $500 from Porters, with the SAE taper for the prop and key way for the flange.

Arguable whether it is cheaper than paying someone $95 an hour to straighten one.

I was at Porters one day and watched an old bloke straighten a shaft with a hammer, took nearly 20 seconds [not mine]. Shafts are fairly delicate. I had the shaft out of my fishing boat a couple of times. It was about 16 feet long and needed about 4 people to carry it. I made a hardwood frame to carry it on the truck tray to and fro from Porters at their suggestion.