Carver 1995 320 exessive exhaust noise

[handyaussie]

This a first post from Handyaussie.
My 1995 carver is LOUD. 78 decibels. I am trying to quieten the beast down. Twin gm 350 with Crusader manifold, riser. recently purchased the boat.
Looking at the exhaust I find 4" hoses 30" long, straight from the riser to the muffler (XC-CAR-P1197). Then out the side thru-hulls.
What I need some input on is:
1. According to the Carver manual. There is a part #74363001 "Exhaust damper" Missing. No suppliers seem to know what this is. Or, what it does. ??

2. Each engine has one muyffler (# above). Basically a 10-12 fiberglass cylinder. 2- 4 inch inlets on side for riser hose.. 1- 5 inch outlet one end, for exhaust to thru hull.
Both my mufflers are mounted so as to slope down towards the exhaust thru- hull. I know of the continuous down slope recommended for exhaust hoses. However, this does not look right to me! A temperature check shows a 5c hotter area on the high end.
It seems to me the muffler should be horizontal to allow adequte water to build equally each end?
Can anyone shed some light on this for me?

#. The original exhaust diagram does not show any way to stop sea water backing up into the system. Except 14 inches of head.
Any help appreciated.

I will check back regularly for your words of wisdom!

Happy Christmas.
DougS

[Viper]

Welcome aboard Doug. A picture of your current setup would really help. If you got that number from Carver, it'll be a Carver number which will differ from the actual supplier. Major exhaust components were likely to be Centek though. If you contact Carver with your hull number, they should be able to help you with the supplier.

The damper should not affect or reduce noise to a noticeable degree. If it's what I'm thinking it is, it's to prevent resonance reversion, a by-product of cam/engine design, valve overlap, etc. The exhaust elbow design also plays a huge role in preventing water reversion. There has been quite an increase of severe damage due to water reversion as a result of this so I would put the dampers back in if they're missing. There should be one after each elbow, and there is a spec for installation distance from the elbow. If you can't get the originals, there should be other after market units available. I know Merc has them, they insert into the exhaust hose. You can use them on any brand of engine.

If the mufflers are horizontal units, pretty sure they are supposed to be mounted level or else you may be directing the water into a section that is not helping to muffle the exhaust. In these and lift type mufflers, water is doing the work and the muffler needs to be level due to the way they're plumbed internally. They are typically directional in that the "TOP" must face up, so there will be port and starboard builds for 2 inlet/1 outlet designs. If this is the case and these got removed previously and they didn't pay attention when reinstalling, they wouldn't be working properly. Try to find who the manufacturer is, they should be able to help. There may be a label on them.

Aside from the clamps right at the elbow, are there another one or two shortly after the elbow that don't seem to be clamping anything? If there are, you may have the dampers that insert into the hose, the clamps prevent them from moving inside.

[handyaussie]

Viper.
Thank you for the quick reply.
I will take a photo of the exhaust system. May be a day or two. We have snow here.
The mufflers are definately horizontal style. I will try centek for more info. on them.

I will also look into the mercury in-hose resonoator solution as well. They are definately NOT there. The marina mechanic had suggested them.

Standby for photos.
Thanks for your help.
Happy Christmas!!
Regards.
DougS

[handyaussie]

[image][/image]

[Viper]

I've never seen a setup like that before. I would try leveling that muffler. Is it up hill to the exhaust port on the hull?

[tomschauer]

Hard to tell from the pictures, but it looks like someone glassed in a second inlet to the bottom of the muffler. Often the exhaust "t's" together and enters the muffler as one inlet. The muffler should be standing straight up causing the muffler to fill with water before expelling water and exhaust, thus keeping the boat quiet.
The way this looks the engine exhaust hose closest to the muffler out let would have little if an restriction that would make your boat sound loud.

[Viper]

It does look like the tube was replaced but I don't think this is a lift muffler intended to be mounted vertically on a base. I don't see a base on it but what looks to be a factory end cap instead so It's more likely to be a horizontal unit. You can't always tell from the outside how it's plumbed internally. Glassed-in baffles will accomplish the same thing in a horizontal unit that you'd get in vertical lift unit (pushing water). A baffle cap over the inside of the outlet with an open top will do the same thing. They usually do that or baffles over the inlets directing the exhaust down into water. The label also indicates to me that it's a horizontal design as they're usually placed such that it indicates which side is the top of the muffler. This is a must for a horizontal install or it won't work right. The angle is a concern though, the above design won't work properly if it's not level. I don't think it's installed properly. Definitely needs to be followed up.

[bud37]

Welcome Doug.....this may help......section 5.3

http://www.carveryachts.com/media/3920/ ... ual_96.pdf