Marinette Boat Forum

My mechanic installed two running takeouts (318s with 1:1 transmissions) to replace the same engines/transmissions. He is having a ton of trouble getting the Port engine alignment right and there is significant vibration over 1600 rpms. He has tried adjusting the engine angle ad nauseam. The isolation spacer between the transmission and shaft couplers appears to be straight. The couplers also appear to be straight and aligned, but then when he tightens down on the bolts connecting the couplers it creates an uneven space that we believe could be causing the significant wobble/vibration. The shafts were not changed out with the engine swap and didn't have problems before. The cutlass bearings were replaced in April.

Anyone have this issue before? Any thoughts on next steps/things to try? Any other things to check that could be causing this?

Thanks!

Tim

Is he using a feeler gauge to get the engines in alignment. Ideally it will be .003" or less out of true. That is as close as i got on my old 28 ft. when I installed new shafts, i could have got it a little better, but the run out on the transmission coupler was .003".

If the coupler flange/ flanges run out it's impossible to align the coupling. So how can you determine if this is the problem? It's not easy, but it can be done.

For the trans side: Mount a dial indicator on trans and spin the coupling over. It should be okay since it's precision machined, but it COULD be bent.

If it's okay then the prop side flange is running out (which is most likely). That means it needs to be machined (see below), but if you want to make sure here's what to do:

Push the prop shaft backwards until it bottoms on the stuffing box. It has to slide smoothly as it rotates or the shaft will wiggle fore and aft to mess up the dial indicator readings. Dial indicate the flange surface as a helper slowly turns the prop, and if the runs out is more than a few thousandths of an inch it has to be fixed.

Pull the coupling and shaft, mount the coupling back on the prop shaft, and have a machine shop turn the face of the flange until it's true.

Since the lathe operation will most likely be needed, I would pull the works out and send it to the machine shop. Had to do that on mine.

Good luck!

Jeff

Thanks, Jeff! Much appreciated. Will come back with updates. Currently in the water, so might not get to pulling the shaft for a little while. How risky is it to run it at lower RPM in the meantime? What am I risking in terms of transmission damage/wear?

Tim

If you run it so slow that you're not getting vibration it might be okay.

Personally, I would run that motor only to get in and out of the slip. My old 32 footer worked fine on one motor.

Jeff

PS: It would be hard to rotate the prop for dial indicating with the boat in the water!

To follow-up and close this out, the shaft was bent just outside of the hull. When turning the prop by hand, you could see the shaft was out of round at the hull. I think the marina bent the shaft with the lift, by having the rear strap too far back and on the shaft. Replaced the shaft, and seems to be all good now.

Tim

That would hav really ticked me off it the marina did that to me!

Lucky it wasn't both shafts.

Jeff

Just a question (for which I think I know the answer)....
If there was no vibration before the chabgeout and the end result was due to a bent shaft where the strap had been placed, does the marina bear rresponsibility?
And, followup, as we pay the marina a hefty sum for work, how do owners hold the marina responsible? Do we have to micro manage the work?

Bill

Bill: OF course, without question, if there were a straight shaft and a bent one after lifting the boat -- and you could show strap misplacement was an issue, you have reason to ask the Marina to take responsibility. I think the worn out phrase "man up" applies. They will duck and run as you know so now it's a question of where you want to spend your hard - earned boating bucks. It doesn't hurt to discuss it and see how they respond. Maybe they would be willing to adjust your fees or give you free in/out - or something that would cost you in the future and would be a minor expense for them. Bargain.

Following up, I talked with the marina owner and told him what I expect happened. I didn't ask for anything in particular (I had a spare used shaft to replace it with). They are fairly accommodating, and I get good prices on everything else (it's one of the cheaper marinas near me). I also have a good relationship with them, for instance I asked the owner to run by the boat when I was out of town one weekend and I got a high water alarm on one of my wireless sensors - I thought it was a false alarm, and it was, but he was happy to stop by and check at 9pm on a weekend night. Because of that type of thing, I could let the shaft go and just mentioned it to him.

If I had pushed the issue, I imagine he would have credited me for the cost of a used shaft in services such as pulling it out.

Tim