Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Clunk when taking off after reverse


iliketoski

Recommended Posts

I have a 2001 Sunsetter VLX. In the last year, I've started getting a clunk, (like the drive shaft is sliding up into the boat a short distance and hitting a stop). This only happens after being in reverse, so its like the shaft is pulled out slightly, then when you take off in forward, as soon as you start to accelerate, you get this slight clunk. I've checked the prop, tried pulling and pushing on it to see if the shaft is sliding. The dealer checked the bushings, but it still continues now for over a year. I'm worried something worse is going to happen. If you know what a slide hammer is, kinda feels like that. Not bad, but definately noticable to people in the boat.

Is there any way something could be happening inside the V-Drive?

Anyone ever heard of this?

My dealer is stumped.

Link to comment

I have a 2001 Sunsetter VLX. In the last year, I've started getting a clunk, (like the drive shaft is sliding up into the boat a short distance and hitting a stop). This only happens after being in reverse, so its like the shaft is pulled out slightly, then when you take off in forward, as soon as you start to accelerate, you get this slight clunk. I've checked the prop, tried pulling and pushing on it to see if the shaft is sliding. The dealer checked the bushings, but it still continues now for over a year. I'm worried something worse is going to happen. If you know what a slide hammer is, kinda feels like that. Not bad, but definately noticable to people in the boat.

Is there any way something could be happening inside the V-Drive?

Anyone ever heard of this?

My dealer is stumped.

coupler good and tight? get a buddy to drive and stick your head in there and try to isolate it. Wonder if your prop might even be loose? is the tranny shifter mal-adjusted?

Edited by 85 Barefoot
Link to comment

If only because it is quick and easy and you can eliminate it as a possibility I'd re-install the prop making sure the key isn't somehow binding up (or wrong size.) Install the prop without the key and make a pencil mark on the shaft at the front of the prop...then reinstall with key and use the pencil mark to make sure it is fully seated.

Link to comment

The coupler is good and tight, The prop is bottomed out against the stop and there is no room between the prop and nut.

I'm not sure I know what the "flex" plate is

Link to comment

Reviewed the link on the damper plate, I wonder if this could move far enough to provide the "clunk". I thinking of putting my palm on the bell housing to try to sense if the clunk is coming from there (or more on the output side of the V-drive.

Link to comment

I've seen a loose prop cause that sound. The prop backs off when in reverse and is pushed forward when in forward. Thump. Coupler would get my second vote followed by low trans fluid. Damper plate is typically a chattering sound however if the springs are broke I could see how it might thump.

Link to comment

Remove the prop, then run it on a hose (wet the driveline first) or put it in the water (keep it on the trailer) and try it. That will tell you if it is the prop.

While you are under the boat, grab the rudder and wiggle it side to side and back to front. Does it clunk?

Link to comment

I tried sitting on the ground behind the boat while on the trailer, tugging, pulling, and pushing on the prop. No movement, (except turning :) ).

It seem obvious to me that the forward force of the thrust, is causing the clunk, so removing the prop would eliminate the force that is causing the issue.

No, not a two liter :lol: rolling around.

I just talked to Vince at Discount Inboard, he said the dampler plate would only likely affect the noise going in and out of forward and reverse. Its meant to soften the transition of the engine speed to the prop speed.

He's betting prop nut, or nut on the end of the prop shaft at the coupling. Doubtful it is anything in the vdrive, which is good to hear.

Edited by iliketoski
Link to comment

After talking to some more folks everyone thinks its the nut on the end of the prop shaft, at the flange between prop shaft and transmission. To get to this nut, do you just have to loosen the 4 bolts on the flange, then the prop shaft would slide down toward rudder exposing the nut?

Edited by iliketoski
Link to comment

After talking to some more folks every thinks its the bolt nut on the end of the prop shaft, at the flange between prop shaft and transmission. To get to this nut, do you just have to loosen the 4 bolts on the flange, then the prop shaft would slide down toward rudder exposing the nut?

i think that there is a set screw involved somewhere, too.

iirc that set screw is used to keep the nut from backing off.

Link to comment

Before you remove the 4 bolts at the drive shaft to V-drive flange, I would soak the drive shaft with water and dish washing soap so that when you slide the drive shaft down toward the rudder (after you remove the 4 bolts and loosen the set screw) you aren't janking up the packing material. Here's the set screw.

IMG_0170.jpg

Link to comment

Thanks, that is a great picture. (I try to keep my bilge clean, but that one is spotless :clap:).

Looks like this one is going to be fun to get to, (a knuckle buster). It doesn't even look like you can get a socket on the head of the bolt.

Link to comment
  • 4 weeks later...

Ok, dug into this last night, disconnected the coupler from the coupler on the transmission and checked the nut on the end. Both the set screw and nut were tight as can be, no issue there.

I went back to look at the prop, after thinking about it, I figure that I keep checking it after its been in forward, and heard the clunk, (forward to put on the trailer), so if it is the prop, it would be moved snug against the nut at this point. So I'm going to pull the cotter pin and try the nut.

Can anyone share how much space they can see of the shaft, directly in front of the prop, I think I've got like 1/2" or so. This may be my issue. The prop is sliding back to the nut. (I need to get the boat on the trailer after being in reverse, but that will be difficult). I'm thinking of putting the trailer in the water and with the bow still attached, putting it in reverse the hopefully set up the situation (if just tightening the nut is fruitless)

Link to comment

You are supposed to have a little clearance between the prop and the strut since that is where a prop puller will slide in between to pull the prop off. If you have a prop puller, you could pull the prop and re install it pushing it as far forward as it will go (check the key while doing this and make sure it is seated right) and then see if there is a gap between where the prop nut threads end and the prop. If there is any space, I guess you could possibly get a large washer and put between the prop and the nut to fill the space.

Link to comment

If you can run it, take the prop off and see if you can replicate the problem without the prop. If it does not duplicate, then when you re-install the prop first do it without the key and make a pencil mark on the shaft at the very front of the prop...then reinstall with the key and note the pencil mark to make sure it is fully seated. If it does not fully seat, you've found your problem (not fully seated, deformed key, wrong sized key, key hanging up in keyway, running out of threads, etc.)

Either way, when you reinstall it is a good idea to lap fit your prop:

http://www.pbase.com/mainecruising/fitting_a_prop

Link to comment

@livetoski: when you load the boat on the trailer, the prop will be thrust forward on the shaft, so if the nut is loose you should see it or be able to torn it or tighten it. You could also check with a feeler gauge.

Based on the comments above, it sounds like the prop and shaft nut are tight so there is something else happening. I would now check the engine and trans mounts as when you engage the prop you create a torque against the engine mounts and a loose mount could make a clunking sound.

Link to comment

Thinking about it again, you are right, the prop would move forward on the shaft. I want to take three measures. the gap at the strut, the gap from the packing nut to the flange, then the flange to the transmission. Put the trailer in the water, (boat attached), give it reverse thrust, pull the boat out of the water and remeasure all three. That will tell me if/where there is movement.

I like your engine mount suggestion and will check those as well.

Very elusive :-(

I'm hoping not internal to the v-drive or transmission.

Edited by iliketoski
Link to comment

Ok, dunked the boat on Saturday, checked gaps after forward and reverse (but only on trailer). No gap differences as measured between the prop and support, packing and flange, flange and transmission. So this tells me NO movement in the shaft or components.

On to checking the motor mounts, but likely can't determine any more until next season.

Link to comment

No, since the clunk only occurs after there has been reverse thrust, (more than just shifting into reverse, thrust above idle). (Plus I don't have a prop puller :) )

Edited by iliketoski
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...