We have one of our 41's, the starboard engine vibrates pretty good. At 1000 rpm the vibration is enough to rattle EVERYTHING in the cabin. above that upto 2200 rpm you don't feel anything out of the ordinary, then it starts back vibrating the cabin. We checked the engine and it vibrates consistinly faster with the higher rpms, even when you don't feel it in the cabin. We replaced the vibration dampner, ran it without the PTO, tune up, change fuel pump. NOTHING is different. Any ideas?

check ur shaft it could be bent or maybe some loose mounting bolts.

If you have taken your eng out anytime recently and the engiene mounts were moved your shaft might not be aligned. Also check your prop and try doing a shaft runout.

Agree with above, Also check engine under load and No load.

We had it in neutral at the dock when we discovered it to vibrate all the time.

If it does it in neutral, it's not the shaft alignment. It's most likely a soft foot situation. Check your mounts for bad rubber isolators. Also, have you replaced the injectors?

we have not replaced the injectors yet. I will check the mountings in the morning.

quote:

Originally posted by jelsenburg:
we have not replaced the injectors yet. I will check the mountings in the morning.

Jim give me a call I'm in global.

Later DMCATAHOULA

You need to get the boat pulled and place a dial on your shaft. Check all your bearings.

Maybe its not your engines, the 41' is so old the whole boat is probably just vibrating apart. Did you check the specs on the rotor gerter?

Well if it was Vibrating in Neutral, and you have checked all the mounts for proper tightness and made sure the rubber on the mounts was SAT. I would check the actuall foundations under the Engine Mounts. We did it to a UTB that sat on a hill forever.We unbolted all the mounts and the shaft,than placed 2 bottle jacks under the front end and took the mounts off and inspected the Aluminum under the mount, than repeated for the aft end. When we did this we found a cracked foundation on the aft Starboard mount where the mounting bolts ran through hauled the boat out fixed the crack than rebolted everything did a shaft alignment and the vibration was gone. Good luck, I hope it is easy on y'all

we had that problem and it was the red gear. we ended up snapping the output shaft on it.

Chief Elsenburg, we did change five ot the injectors last week and we still had the problem.

If this is doing this through all rpm's, out of gear, than I agree that it may be a problem with the engine mounts or engine beds. Aluminum has a tendency to crack in engine beds. Do a visual inspection on the whole bed structure all the way down to the bilge. Next I would loosen the top nut on each mount, lift engine slighty (one mount at a time), and see if the mount moves or is loose on the engine bed.
One other simple check I would do before the above, is bar the engine and inspect the rubber blocks through the inspection port on the spider gear at the flywheel/twin disc drive.
Good luck.

I will be back at the unit this weekend, I will see about climbing my happy butt down there with a flashlight and mirror and see what I can see.

I work at BFC and I think I've seen every kind of vibration possible out of the 903. If none of the other common things have worked try pulling the PTO and replacing the PTO bearing.

Last time we had the Sector loaner UTB it also had the same problem and we found 3 snapped vibration dampner bolts!! We are currently having the same problem. We hauled the boat conducted a alignment, ensured the saft saver's lip installed properly, inspected all mounts, etc. Our next step is to pull the PTO the check the Vibration Dampner bolts. If I don't see any problem then I'll CASREP the boat for someone to fund some injectors. I hopping it's the BOLTS!!!! Good Luck to you, MKC