CObarry

OK, I know most will say to dump the silent thunder and go with regular thru hulls (and I will eventually), but is there a way to bondo/duct tape/super glue the thing to stop the rattling at idle? What is it that's rattling....baffles? Only happens on the port engine...the starboard side is fine...

ThirdBird

Is yours the newer integrated style platform or the pre-'92 big bolt on platform?

Iggy

If you look through the exhaust out let, flashlight required, you'll see a vertical baffel plate about 6-8" back. It is bonded to the top and sides. Yours probably came loose. You could take a long punch and a hammer to knock it off then pull it out. I think it'll fit through the opening.
A few of the guys here have taken a whole saw and opened the baffel to allow more flow.
Do a search on silent thunder and you'll see several threads on the topic.

With the current trend in noise regulation I'd rethink your idea of removing the platform and going with open pipes. You may find yourself having to by expensive mufflers.

ThirdBird

I've had three pre-'92 Formulas with the full platforms. Never had rattles on any. I think the rattle issue is more prevalant on the newer models that bolt-up under the integrated platform. Those Silent Thunder boxes are not as rigid and heavy-duty as the older full boards.

They are easier to remove and install though. Pull it off, find the loose culprit, fix it and put 'er back on.

Bill272

Here's what the inside will look like, assuming it's the same as the 95 336. Mine was split along the edge at the bottom of the pic and cracked in a couple of places. I took it off and never looked back. I'll try to fix it with 5200 and some small machine bolts if they decide to crack down on loud boats. Until then, she's staying loud and rattle free.

CObarry

Thanks for the responses!

Iggy, My boat is a '96 336, so it has the bolt-up-under-the-swim platform type. I'll try looking through the exhaust port to see if something is loose and easily removable.

Troutly, that's my end game, clamp on or thru bolt mufflers. I don't want to wake my neighbors up every time I start the engines.

Bill, how much does this thing weigh? If I can't see anything by looking through the outlets it's coming off for further investigation. I've got some leaking gaskets at the transom that need to be fixed anyway.

Iggy

I doubt yours is the same as mine. I have the bolt on swim platform not the same as yours. I believe they are constructed differently.
Yours should be like Bill272's.

Bill272

I had the same issue. Soot on the transom where I could see the exhaust was leaking past the platform. At the very bottom of the pic you can see a white crescent shaped spot. The seal between the exhaust chamber and outer shell was split there and that spot was rattleing and actually sanded a similar spot in the gelcoat on the boat. Took it off down to the fiberglass(I still need to fix that).

Anyway, to take it off I removed the ladder and the bolts off the back of the platform. It had some caulk that was holding it up, so I pulled down on it and it stayed there with a couple of inch gap at the back. I tied some clothesline to the outside bolt holes and secured it to the cleats up on he back to hold it while I took out the screws that held it to the transom brackets. Once those were off, I pulled it straight back. The gaskets around the exhaust will stick and the tips extend maybe an inch off the transom. Once it's clear of the adhesive gaskets and tips, it will come off and hang by the clothesline (I did that because I did it alone and wasn't sure how heavy it would be.) I'll guess it's weight to be 40-50#, more bulky than heavy. It would have been easier with a helper.

Formula Outlaw

The box on my 89 311 is close to 200 lbs or better.

One of the reasons it's not on the boat anymore.

offthefront

iTrader: (1)

I NEVER heard a rattle .....then ........Outlaw just happened to mention a rattle .....THEN thats all I %#$#@$%^& could hear was rattle .....
I had my platform off this winter and as Iggy sez the partitions were loose ..we glassed em back in and now quiet as a mouse .... ....Mine is older style box .... A ***** to get off and on ......I would think the newer style would be ez fix ..