7.4 Horizon 380hp V drive noises

Harborite88

New Member
May 28, 2018
28
Boat Info
1998 Sea Ray 330 Sundancer
Engines
Twin 7.4 Horizon’s
Hey guys, this is my first post but I've been looking for a boat for a while and I think I finally found one, it is a long ways away so I've been doing everything without physically seeing the boat yet. It is a 1998 330 Sundancer with less than 500 hrs and I had the survey done today. I haven't got the survey report yet but my surveyor sent me a short video of the engines idling and they sound awful to me. Some research has led me to think that maybe it is actually the v-drives making noise, and this is a cell phone video so it may sound worse than it is but maybe you guys can take a listen and see what you think. If the rest of his report goes well I plan on having a mercruiser mechanic look at the propulsion system. Thanks in advance for any ideas.

 
Sounds like the engines are causing the trans gears to chatter.
This is often due to a poorly idling gas engine.
A standard tuneup and possibly fresh fuel will normally eliminate most of the chatter.
However do at least a compression test on all the cylinders.

Cheers
 
That's the dampener plate. Its bolted to the fly wheel to take some pressure off the tranny when putting into gear. 95% of the time a good tune up takes care of most the chatter. There's no damage going on here. It's just sounds bad. The other 5% of the time the dampener plate needs to be replaced.

Generally once the rpms while in gear reach 800 to 900 the chatter goes away.

You might want to do some research on 7.4s and exhaust systems in that time frame and size boat. Water ingestion via the camshaft and log exhaust stuck water mist back up into the engine. Sea ray solved that issue with lift bucket exhausts... Do a compression test!!!
 
Thank you for your replies, I really appreciate it. That definitely makes me feel better. I'm also going to have a mercruiser mechanic do an inspection and compression check.
 
the guy surveying the engine should have know that????
It was a pre-purchase and valuation survey of the entire vessel, not a mechanical survey of the engines.
 
Looks like that was announced in 2001. I'd call hurth and verify. They would have 17 years of historical data on long term effects on using motor oil. Every mechanic I talk to today says that's the dampener plate rattling and not harming a thing. Which I tend to believe and experience myself on a brand new 630.
 

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