07 Hammerhead 383 Knocking Noise

[shawndoggy]

Ok, it's officially been confirmed as normal. But how do we fix it because it drives me

you could try cognitive-behavioral therapy?

[88schleining]

you could try cognitive-behavioral therapy?

I have 07 383 and it has done it from day one! As you increase the idle it goes away......is it the knock sensor failing? The dealer says he can't hear a knock....must have the stereo on when diagnosing.

Edited September 15, 2013 by 88schleining

[AZLakebum]

On 9/10/2013 at 6:45 AM, Ndawg12 said:

If you've experienced this issue with the same motor/tranny/vdrive combo then you'll easily know what I'm talking about, but for others I'll try my best to describe it.

Once going into idle forward (no acceleration, 650rpm, ~3.5mph) I get a knocking/vibration sound that comes from the vdrive area. Even the slightest acceleration will make it go away, 700rpm. My dealer changed the ATF in the vdrive to straight 30W and that didn't help at all and then Indmar strongly suggested that I put the recommended ATF back in. Indmar said something about the Hammerhead being a "hotrod" motor with a different cam and that the relationship between the tranny and motor will make this knocking/vibration sound.

Ok, so it's normal (per Indmar) but I searched on here and didn't find much info on it or any members complaining about it, so I'm thinking mine is louder and more annoying than most. I'll try to shoot a video of it this weekend.

.....found the correspondence from Indmar:

If they put 30W oil in that unit you need to get it changed back to ATF. That transmission will not survive on 30W. The 383 engine does not idle as smoothly as your Monsoon did. The 383 has a big cam so it lopes a little. Some trans noise at idle that goes away when some load is applied is normal. All of the engine/tran packages do that to some extent but it is more noticeable on the 383 because of the hot rod cam.

Like I said, it's very annoying, especially with my OCD tendency, but if it is normal I would like to hear some others backup this claim.

It sounds like I have the same thing on mine also...I would describe the sound as if something metal broke off and was rattling around inside the vdrive or tranny. The noise is only present when in gear and idling forward, but goes away when any little amount of additional throttle is given. ALTHOUGH...I didn't always have this noise until I put the throttle into reverse too quickly after coming off the throttle (the neutral locking mechanism broke on my boat so was using a throttle for a period of time that would swing freely between forward, neutral and reverse). After putting into reverse too quickly, that sound started. Only suspicion was the drive plate (dampner plate?) or some other component in the vdrive housing. Clearly something is able to rattle around at lower rpms but once we get going, the centrifugal force (or other pressure) keeps the thing from rattling...maybe something is just loose and not broken. Doesn't sit well with me knowing that something is loose inside of the vdrive or tranny but dealer said to run it like normal until something completely fails...more than 300 hours later, the sound is still there, but hasn't gotten worst nor has anything failed. Weird.

[jwl019]

Glad to find out this is normal!  I could not figure out where the sound was coming from on my demo, but yes it is kind of annoying to hear.

[wakesonthesnake]

I have it as well.

[Jolove]

Anyone find out for sure what is causing that noise??

[WGjames]

Same on my 08 247 from reading these and super smooth at speed.