Knocking Noise

aero3113

The last two times out I heard an inconsistent knocking noise (I think from starboard side). It starts about 2-3 minutes after up on plane (not at idle) and only happens after the first run of the day. It will go away about 10 minutes into the run I think. On the way back to the dock later in the day no noise. It happened Thursday night also, but yesterday afternoon when we headed back, no noise. It seems like if the boat sits for a few days it will happen. I’m thinking gimbal bearing or u-joints, what do you guys think? 

Black_Diamond

Gimbal bearing. 

mattie

Doesn’t necessarily sound mechanical. Anything different on the exterior? I’ve had my vhf antenna slap the sides of the boat in down position during odd winds. Weird.....

Also on our last Rinker, first runs of the season we had an unknown knocking. Even had 2 marine mechanics take the boat out. Could not figure it out.
Had the boat even taken an hour away to the dealer, totally stumped.
Mid summer I figured it out ~ I had a new Bimini made over the winter, it would lift a bit at speed & thump the support posts in their sockets. Pfffffff.

aero3113

Nothing new on the exterior. When I do hear it, I’m pretty sure it’s coming from down low near the engines. I’m planning on pulling the boat soon, will pull the drives and inspect everything.

mattie

Maybe it’s some of the crap you knocked loose in the waste tank.....lololol

might have a pooberg in there.

Liberty44140

Is it really a knock? Or could it be a tap or a tick? Tap or tick down low is definitely gimbal bearing as BD said 

aero3113

Liberty44140 said:

Is it really a knock? Or could it be a tap or a tick? Tap or tick down low is definitely gimbal bearing as BD said 

It’s definitely a knock , not a tap or tick. Almost like a dull thud. Maybe a pulley bearing going? If I knew mechanical was ruled out almost like something was hitting the hull. But if it was something external why only at certain times consistently?

JimGuy341

Had a similar issue and it turned out to be the u-joint.  

JimGuy341

I should note: when I heard the knocking noise, it was also accompanied by a vibration.

aero3113

JimGuy341 said:

I should note: when I heard the knocking noise, it was also accompanied by a vibration.

No vibration when I hear it. Would yours only do it every once in a while? Not consistently?

JimGuy341

yes, it was sporadic.  And when it did happen, it was usually when we were coming off plane.  

aero3113

I pulled the starboard drive today and the U joints look fine with no play. It’s possible the noise is coming from the port drive. I’ll have that off in a few days. This drive does have the lower seal leaking slightly. I didn’t lose any oil this season, must be a very minor leak. I’ll have that repaired.

aero3113

Port side U joints look and feel brand new. Would a bad U joint be obvious? The starboard side has some surface rust but seems tight and smooth from what I can tell.

Port

Starboard

aero3113

I checked all of the pulleys and pumps also, they seem smooth also. Starboard lower tensioner pulley might be a little dry but spins freely.

aero3113

I’m thinking it might be internal to the drive 😬.

Aqua_Aura

That u-joint looks like it's ready for replacement. Are you sure the bellow isn't bad as well or maybe that's just rust from a previously bad bellow?

Oh I read that again I see you said it seems to be surface and doesn't have any play in it 

aero3113

Yea @Aqua_Aura no play and just seems like surface rust, no water in the bellows.

Aqua_Aura

Have you drained the gear oil yet, milky? Too bad you didn't see the u-joint before you had it in the water to know if the bellow is leaking. Although I'm sure your gimbal would be rusty and there would be some water in the boat if it was. 

aero3113

Yea, no water in the bellows definitely not leaking. I was going to let the shop drain it but maybe I’ll do it just to see if anything is obvious.

reneechris14

How's the alignment to the coupler, if its off it will give some noises. Wish there was a way to spin a drive when it was off?

aero3113

I’m going to order an alignment tool. From what I can see the splines look perfect with no wear on both port and starboard.

J3ff

I'm still having a knocking noise when the motor is hot and in N. At this point it's got to be something with the coupler. Oh well. I feel vibration up on plane, but hard to tell if it's "normal" or not. 

Aqua_Aura

Then run the drive without the engine 😆. Sorry that was too easy. 

Good point Al you must be a boat mechanic. 

aero3113

Alswagg said:

Run the engine without the drive. Verify the knock is present or gone.  Then go from there 

Al, the noise is intermittent. I ran the boat at idle from my dock to the ramp to get pulled, no noise. Then I ran the engine to flush and winterize, still no noise.The last run up on plane was for a half hour @3800-4000 RPM’s and no noise. But the day before at the same RPM’s I had the noise for a few minutes then it went away.

raybo3

shawnmjr said:

Aqua_Aura said:

Then run the drive without the engine 😆. Sorry that was too easy. 

Good point Al you must be a boat mechanic. 

What cools the engine if an outdrive isn’t attached and what keeps the impeller lubricated?

You have to hook up a "garden" hose to the intake hose of the boat where the drive connects. Very easy to do......... Just say'n

aero3113

I drained both drives today and nothing obvious, no metal on any of the magnets and no water. I did find that both drives had the wear pads missing or broken, so I replaced them.

aero3113

@Alswagg , the drive that I’m thinking the noise might be from is the drive that popped out of gear and into neutral while I was up on plane a few weeks ago. Could this have any thing to do with the noise? I don’t remember hearing the noise when it happened though.

aero3113

Don’t know, that’s what I’m trying to figure out. It happened once and that’s it. Shifting is smooth with no banging or other noises into gear. Would one of those cause a knock that goes away? Hoping to have the drive at a shop this week.

PickleRick

I'm waiting on one of you guys to do a DIY tear down, replacment of the clutch cone and bearings.  Ive seen a few YouTube videos of ths clutch, showing where I believe it should be grooved and they have worn smooth iirc but I've yet to see how they remove/press everything back together....also tolerances...i want lots of info on backlash, preload , torque specs etc that is needed.  

From what I've read clutch cone replacement is a common repair on the bravos.

aero3113

I think @reneechris14 did his cone clutch from what I remember?

Liberty44140

Any chance the noise is from something else rattling? Stern anchor banging against a metal brush handle in your aft storage?