Gimbal bearing noise

[CTD]

Ran my boat for the first time today and after about 15 minuter a noise developed, sounds like a grinding more noticible at lower speeds. It dosn't change when turning the wheel. I kind of suspect its the gimbal bearing. When I put the engine back together I made an alignment shaft on a wood lathe and I was sure I had it aligned ok. The drive (cobra) went on a little stiff but that was before it even got to the splines, once it hit the splines I turned the driveshaft a little and gave it a kick and it went in. The bearing is an original from 1987 so it could just be time to go or I have an alignment problem. How accurate does the engine alignment need to be, should I buy a metal alignment tool or do boat shops rent them? Its a 1987 4.3 OMC Cobra

 

[hondon]

Re: Gimbal bearing noise

You have'nt gone into detail about the noise.A common misdiagnosis of gimball bearing noise is attributed to the exhaust shutters at the top of your y pipe.The neoprene coating gets worn or burnt off over time and causes a rattle most prevailent at idle.That is a big beefy bearing and with regular lube and no contamination they last a long time.However, 17 years is kinda a long time.

 

[WillyBWright]

Re: Gimbal bearing noise

Bad gimbal bearings usually get louder with tilt and steering extremes. But if it's original, it's probably overdue.<br /><br />The closer to perfect you can get with engine alignment, the longer the related parts will last. If you can push it on by hand until it's snug on the mount, you're pretty close.<br /><br />Check the gearlube in the upper half of the drive. I hope that isn't where the grinding noise is coming from, but...

 

[CTD]

Re: Gimbal bearing noise

Guess I forgot to mention the noise dosn't change when tilting the outdrive, however the u joint starts making some noise at the upper limit of the trim function. I think the u joint noise is normal. The grinding is a rrrr rrrr rrrr rrrr type noise, it sounds the same in neurtal drive or reverse. I thought about the upper drive unit being a possible cause, the oil was full when I left, guess I should drain it and check for metal. I looked at the shtters before I put the engine back in and they looked good. I think this unit has less than a hundred hours on it. It was last registered in 1988....OK its later I took the bearing out and it is noisy, guess I'll replace it and see what happens.

 

[IMP]

Re: Gimbal bearing noise

I have a 4.3 L Cobra OD. I just changed out the Gimble bearing and it was a breeze, with the exception of putting the OD back in. There was some resistance but no more than expected for the weight of the thing. It did not solve my problem. I believe it' s, in my case, uppergear case bearings. Good luck.