big vibration and knocking. loose prop shaft

[kidmet]

1985 reinell, 5.0L omc cobra. Took her out, first at full throttle she'd only get to 4500 rpms. Then when bringing her in she had a bad vibration and a knocking sound in the prop lower unit area. When I got her out (swam her in) the prop shaft has some in and out play. Is this normal? Could this be my issue? If not normal, what could be the causes and possible easy fix?

 

[kidmet]

Re: big vibration and knocking. loose prop shaft

Looks like it happens in neutral too so I think prop shaft can be eliminated.

 

[Grub54891]

Re: big vibration and knocking. loose prop shaft

Drain the lube,see what it looks like. Any metal shavings,chunks of gears/bearings? Water in the unit? See what ya can see,take some pics,post them on here.
Grub

 

[jerryjerry05]

Re: big vibration and knocking. loose prop shaft

The 86 5.0 if set up right,shouldn't get any more than 4200-4600 anyway.
The play in the prop shaft is normal.
Do like Grub suggested.
Drain the oil, check the oil.Remove the top cover and check for damage.
Pull the bearing carrier and check for damage.

 

[kidmet]

Re: big vibration and knocking. loose prop shaft

The 86 5.0 if set up right,shouldn't get any more than 4200-4600 anyway.
The play in the prop shaft is normal.
Do like Grub suggested.
Drain the oil, check the oil.Remove the top cover and check for damage.
Pull the bearing carrier and check for damage.

Does there happen to be a good how to guide for these procedures? I'm great with an engine, never worked on the outdrive.

 

[kidmet]

Re: big vibration and knocking. loose prop shaft

Ok, I drained the oil, it was army green and black. The top screw had some small shavings of metal, but nothing big at all. No big metalic parts flowing out either. Not sure if this says anything. I will open the top cover (is this where the dipstick is?), and also look at the bearing carrier as well. One more request, any info on where the bearing carrier is?

Here is a video:

 

[Boomyal]

Re: big vibration and knocking. loose prop shaft

....and what were we supposed to discern from your vid?

 

[Idlespeedonly]

Re: big vibration and knocking. loose prop shaft

I believe a disassembly or replacement is in your future. You really shoudnt run the motor with the drive trimmed up that far if it isnt necessary. It might be worth pulling the drive off and see what the u-joints look like.

 

[kidmet]

Re: big vibration and knocking. loose prop shaft

....and what were we supposed to discern from your vid?

The sound the boat is making that is the subject of this thread.

 

[kidmet]

Re: big vibration and knocking. loose prop shaft

I believe a disassembly or replacement is in your future. You really shoudnt run the motor with the drive trimmed up that far if it isnt necessary. It might be worth pulling the drive off and see what the u-joints look like.

Yea, I opened the top cover and the gears look good. I think it's got to be further up the chain somewhere. Definitely will have to pull the drive off.

 

[wcasey5]

Re: big vibration and knocking. loose prop shaft

If the oil looks fine, then it has got to be the gimbal bearing, or the U-Joints. Better replace the Impeller starting it with no water.

 

[kidmet]

Re: big vibration and knocking. loose prop shaft

If the oil looks fine, then it has got to be the gimbal bearing, or the U-Joints. Better replace the Impeller starting it with no water.

Those 3 are my suspects as well. I will be replacing the impeller anyways (haven't in a while). Pulling tomorrow to look at ujoints and gimbal.