Transmission/Damper Plate Noise

[riwanika]

Can anyone confirm if this sounds like a failed damper plate? Please see the link below to my video:

https://photos.app.goo.gl/STsoZZ6n4WuqkvUP6

The following has been done and checked:
Timing
Mixture
Idle Speed
Operating Temperature
Engine Oil Level
Engine Coolant Level
Transmission Fluid Level
Shaft Alignment to .003
Packing Gland Drip Set to 1 drip per 30s intervals in gear

I'm so tired of beating my head against the wall with this boat and I would like to get it running. My daughter is due in October and I need to get some of these things wrapped up before she gets here!

[Viper]

Before you do anything else, I'd say you have a runability issue that you have to solve before you go any further. I'd say most of that sound will likely go away once the engine is running smoothly. That's what it sounds like to me. Maybe the other guys will pick up on something else.

When was the last time you had an ignition tune-up, replacing all the parts?
How old is the fuel and fuel filter? Any water in it?
I'm assuming this was in neutral?

[Alaska 530 Voyager]

Does that sound go away if you idle up a bit? It does sound like a dampener plate to me.

[riwanika]

Alaska 530: It was so bad I didn't want to rev it and risk damage. With the transmission in neutral the engine revs freely all the way up to the rev limiter and sounds amazing. As soon as it's popped into gear I get the rocks rolling around noise just like in the video

Viper: all ignition parts are brand new, plugs, wires, cap, rotor, it has electronic ignition so no need for points and gap settings. Fuel is fresh fuel filter has been replaced and no water in the fuel. The video shown was in forward gear at the very end it was popped into neutral and you can hear the engine running smoothly at appx. 800rpm

[bud37]

How does the engine run under load ? I would try to avoid revving the engine at the dock unloaded....damage can result from water ingestion and any engine can rev smoothly even with a dead cylinder, with no load.

It does seem to have a knock to it....kinda hard to pick it up clearly though from the video sound.

[riwanika]

bud37 the engine runs great, I only recently started having these issues. I had a rear main seal leak and pulled the engine and trans apart to replace the seal, then reinstalled it all only to find the rear main seal was the wrong one, so apart it came again and went back together. The knock/tick sound could be the loose exhaust clamp that was right by my camera allowing a little bit of exhaust/water to escape. I just finished an alignment that day and started it up only to hear that god awful sound coming from what sounded like either the transmission or the flywheel area. Needless to say I was pretty bummed out.

[Viper]

I listened to it again, maybe it's me but I still hear something that indicates she's not running quite right but without being there, it's hard to say for sure but I hear a couple of hesitations. You could actually see the hesitation in the flywheel unless that's you putting it in and out of gear a few times. To be sure, put a mark on it and shoot a timing light on it or the timing plate and see if the mark moves or remains steady in the same place. If she's not running right, you'll get a tranny chatter at low rpm, same as a bad damper.

Revving up in neutral ok doesn't mean that much to me, that's easy to do and sound normal with no load. FWIW, you should not run at high rpm in neutral, you could damage the engine at that rpm with no load.

The damper plate is a possibility for sure but what I'm trying to convey is that you make sure the engine is running properly before condemning the plate and going through the work involved to replace it. Many have been fooled by a runability issue that wasn't so apparent into thinking it's a bad damper or transmission.

What idle rpm is she running at in gear?

[Cooler]

Is this sound happening in just reverse, or in both reverse and forward? I have heard a lot of boats with tranny clatter in reverse, and then quiet in forward. It is pretty common actually, especially at low RPM's. The gears in transmissions are not machined on the reverse side the way they are with forward side, and sound like rocks grinding. A boater in our marina had his damper plates replaced, ( $4800 ), thinking they were shot. Result was nothing changed, but the mechanic opined the new noise was normal due to typical reverse gear chatter. That was on a Volvo set up. Good luck! er