Hi guys - I have a 2005 Malibu Response LX with an Indmar 320 LCR Engine. A few times over the summer and then yesterday we heard a clunk sound going from between idle to fast out of the hole. Some have mentioned a loose prop, loose pylon, and then failing drive damper. The prop is tight and the pylon is tight. My son actually caught the sound in this video.
https://youtube.com/watch?v=IzZUo2iTw9Q My googling the forums though it sounds like a failing drive damper will have a rattling sound in the transmission at idle speed. I'm not hearing that and it my driver says it was clearly a "clunk" sound out of the engine box. I'm looking for direction here if anyone has any ideas. I've messaged my dealer also.
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Let’s just say he hasn’t dove my boat since
As 2Valve mentioned. Open up the engine cover and repeat the maneuver with some one watching.
You need to check all the drivetrain components. This sounds like a bunch of things I’ve experienced in racing and recreational boating. Check your prop shaft couplers, the prop nut, tranny mount, strut and basically everything from the coupler out. Those clunks can be internal to a drivetrain component BUT if they are from the coupler down to the prop it can end badly if not found. Trust me.
Make sure the prop is not hitting the strut
Make sure the prop is forward on the shaft and NOT moving on the taper.
Make sure your prop shaft is TIGHT in the coupler to the tranny and not slamming forward when the prop applies force.
It’s very difficult to find running gear that is loose by hand. The slamming is done under high hp you can’t duplicate by hand. Look for wear, friction marks and similar.
I wouldn’t use it until found. Hopefully it’s in the tranny or just something loose.
It sounds like you have kids in the boat, make sure you find it. I put a boat on the bottom of the Parker Strip with my wife and 3 kids in it while I was skiing behind it because of a parts failure. (They were all fine, a fuel filter failed and caused a fire.. I sunk it intentionally. Still have it) You don’t want those memories.
It appeared to me that when the line became fully taught with load that is when the clunk sounded. My hunch is the pylon, and if it is tight, check what it is tightened to. I would do process of elimination above to help rule out stuff.
I now use green bearing retaining loctite on any splined coupler that isn't meant to slide.
Sounds like I need to:
1. Check the pylon. I guess I'll e-mail Malibu and find out what the torque should be. I'm relatively confident this isn't the issues as wouldn't the sound come from the pylon and not the engine box?
2. Change the cap and rotor. I changed it at 500 hours along with plugs and wires. The manual calls for this annually or every 100 hours I think. Most mechanics have told me "if it ain't broke don't fix it" when it comes to the cap and rotor but it's cheap to change it out. This sounds like it could cause the engine to backfire.
3. Check the strut bushings again along with the prop. I checked my prop a week ago because 3 weeks ago I had to install a new key. The old one was shot and the prop wasn't staying tight on the shaft. A week ago the prop was tight and the strut bearings looked fine. I didn't seem to have any play. The strut bearings were replaced 4 years ago when I got fishing line stuck in them. It ripped all the rubber right out so I do get under the boat and check on this.
4. Verify the coupler is tight to the back of the transmission and there is no forward play when torque is applied from the prop out of the hole.
Sound good?
"3. Check the strut bushings again along with the prop. I checked my prop a week ago because 3 weeks ago I had to install a new key. The old one was shot and the prop wasn't staying tight on the shaft. A week ago the prop was tight and the strut bearings looked fine. I didn't seem to have any play. The strut bearings were replaced 4 years ago when I got fishing line stuck in them. It ripped all the rubber right out so I do get under the boat and check on this. "
Just curious, did you install the key and prop on the taper properly? (Im not questioning your mechanical abilities) If the prop isnt fully forward on the shaft and the prop is hung up on the key it will move back and forth under power. Even if the nut is down tight on it. At high RPM it will shake badly since its mis-aligned. Best way to install the prop with a new key is to put the prop on the shaft/taper all the way forward and mark the location on the shaft and the distance to the strut. I torque the prop at this point. Then pull the prop and install the key. When you install the prop MAKE SURE the prop is in its marked position prior to installing the key, if its back any from the measurements the key is hangin up the prop on the taper. Torque the prop and always install a new nut....all of my propshafts are drilled for a pin to kep the nut from backing out. Slower direct or V-drives wont present this imbalance as much to the occupants but your strut bushings and etc. will go out sooner and you may bend the tail of the prop shaft.
I'm still looking for an answer on the drive damper? Anyone, think I can rule that out?
Like I mentioned before, give it some power in reverse then hit it like you were pulling a skier and see if the clunk reoccurs.