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OMC Knock Noise

J

jkesselr

Guest
"Hey guys,
I am new to boa

"Hey guys,
I am new to boats and bought a boat from a friend of mine with a boat repair business. It is a 79 Seaswirl with an OMC 800. The story was the guy that had the boat had the block crack, he pulled the engine with the intent to replace it and came on hard times. He sold teh boat with no engine. I bought the boat with no engine and then bought a good used 305 (are there really any of those?
lol.gif
) I put the engine in, did a bunch of other work and have it all dialed in... The trouble is there is a knocking sound from the outdrive area. It sounds like a rod knock, but I know the engine is good and didn't have any noises as it was recently ( as in in the last couple weeks) in another boat and performed flawlessly. My friend said he has never heard a noise like this before from an outdrive. He is busy trying to run his business, so I am basically on my own to figure it out. Any ideas? It sounds like it is coming from the area where the drive goes through the transom. I have not moved the drive from one extreme to the other, but the drive was turned a bit and it made it the noise, turning the drive strait did nothing to change the noise. Also, it makes the noise at all different RPMs. I even pulled the coil wire and cranked it over and could still here the noise a bit. Is theer a chance that this could be ball gears? They are worn, but I'd say the part s worn away maybe 3/32 of an inch. Basically the teeth are a nub, and that nub is worn away a bit - like not quite 1/8 of an inch. When the boat is in neutral, the prop turns a bit, but if you put your foot on it, it stops. Is that normal? There is also a bit of a grinding noise when I slowly shift it into gear - is that normal too? Sorry to ask so many dumb questions, but I am new to this."
 
"The noise is only in neutral?

"The noise is only in neutral? or also in F and R?
Is the tilt down all the way?
Drain all 3 housings into 3 separate drain pans and look for metal.
Turning the drive changes nothing - these drives have no u joints and the mesh of the ball gears stays the same as the drive turns.
If the oil is not metallic, try adjusting shift cables.
Your description of the ball gears sounds like they are pretty much "as new""
 
"This would be an example of a

"This would be an example of an Itermediate Ball Gear that could be described as well worn and in needing of replacement.

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This is what my gear set looked like prior to my refurb. Cleaned everything up and kept them. IMHO these are quite usable:

82868.jpg


If your ball gears are worn enough and or the drive is not completely in the down position, it could produce a sound similar to what you are describing."
 
"The drive was only as far dow

"The drive was only as far down as I could get it while on the trailer - basically all the way down, save a little bit. my ball gears look something like the lower set shown on the Right. maybe a tad worse, but not much. The noise is in both forward and reverse. How much of a job is it to change ball gears? I am guessing the shift cables need to be adjusted based on the fact that the prop turns a bit in neutral. Would a poorly adjusted shift cable cause the knocking? I would think if it was an issue of not having tension between the two and the slop allowing for knocking, once in gear, it would stop, but maybe I am over-thinking this. Thoughts guys?"
 
The noise is only in neutral?

The noise is only in neutral? or also in F and R?

Drain all 3 housings into 3 separate drain pans and look for metal.

Your description of the ball gears sounds like they are pretty much "as new"
 
"if the shift cables arent pro

"if the shift cables arent properly adjusted, and its in neutral the prop will still slowly spin. had this problem last week, and it takes a bit of fine tuning to get it to really be in neutral when you shift it into N.
with the engine off, have it set in N, and turn the prop (assuming its on the trailer) see if it makes that knocking noise."
 
"It makes the noise in forward

"It makes the noise in forward, reverse or neutral when the engine runs or is being cranked. It speeds up with RPM. I have not tried turning the prop by hand and the boat is 50 miles away. I am headed there this weekend to hopefully determine the problem once and for all. I am about ready to say to hell with it and run it until it breaks. It will be expensive, but at least I'll get to enjoy the boat a bit and find out for sure what the issue is. It is getting old working on it and throwing money at it and just getting to see it sit on the trailer and watch the summer roll on by... Thanks for any help you guys can give!!! Have a great afternoon!!!"
 
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