Who knows the most about sea ray exhaust systems?

[Stephen Haley]

I'm looking into buying an 83 Sea Ray Sun-dancer 24.
It has a newer engine, 1998.
It's a 5.7 V8 stern drive, or IO if that's more popular.

I'm told that thru hull exhaust's are not as good or SAFE as thru prop exhausts.

What can anyone tell me?

Something to do with fresh water back-washing into the exhaust system and then into the engine (cylinders).

What can anyone tell me about this year model of Sea Ray. was it a thru hull or thru prop?

Thanks for any info.
Stephen

 

[nlain]

Re: Who knows the most about sea ray exhaust systems?

I/O's or Sterndrives exhaust thru the prop hub as well as two holes in the drive mount at the transom, there is a chance of water pushing back to the engine with outdrive or thru hull exhaust, what prevents that from happening is the riser, it loops up above the water line so the water will not get to the engine. With that said, do not be running on plane, pull the throttle back to idle position and turn the key off, if you do that when the boat settles in the water, water will push to the engine. Either exhaust is fine and should cause no problems. I do not know how this particular boat is set up but my guess would be exhaust thru the outdrive.

 

[Stephen Haley]

Re: Who knows the most about sea ray exhaust systems?

nlain

Thanks. My last boat, a Trojan sedan, 1969 had 4 inch pipes punched out the transom and was visible by just looking over the back.
This boat I'm thinking of buying has a fiberglass swim deck and you can't see much.

Here is a pic of the engine/compartment if it helps any.

http://www.boattrader.com/listing/1983-sea-ray-sundancer-96825320
(if it doesn't click and open you may have to paste it)

Are the two square black boxes part of the water/exhaust system? IF so what function do they provide and what service is/are required on them, if any. I don't see any risers in the pic but the pic doesn't show everything.
It's a 98 motor in an 83 Sundancer.

I'm waiting on a surveyor to get back with me on performing a survey but I don't think it's worth the asking price. Seems more realistic at @ $9000 if it's in excellent shape physically/mechanically. What do you think, or do you have an idea.

Thanks
Stephen

 

[nlain]

Re: Who knows the most about sea ray exhaust systems?

You have water running through the manifolds and risers, the black boxes on top of the exhaust manifold, the water cools the manifolds, risers and the exhaust going out into those rubber holes. There is maintenance so to speak, you need to pull and check them for rust, saltwater use every three to four years, freshwater use they last much longer. They need to be checked due to the fact that when they rust through you get water into the engine, hydro lock, possible engine replacement. You need to check with your mechanic to find out the length of time. If you do some of your on work it is a job you could do.

The pic does not help much, cannot see where the exhaust goes from the risers, you would have to get down and look to see where it goes. I am thinking out the outdrive, most I/O's do from the factory.

Your surveyor could tell you since he is checking everything.

I would offer the price you mentioned, even in good shape it is an old boat. You can also look at others of similar age and size online and see where they are priced, boat trader, craigslist, ebay places like that.

 

[Stephen Haley]

Re: Who knows the most about sea ray exhaust systems?

Thanks again very much for the insight.

Now I'm gonna ask what I already know is a stupid question but I don't know exactly why.

Why is the exhaust cooled in lieu of being fitted with mufflers and ran out with an appropriate riser in the piping.

I am a retired business owner, seem to think that a dry exhaust system should work but I'm sure I'm thinking with my head in the dark space.

Even a quality high temp insulation could be applied (we did it for steam piping) and prevent some of the heat build up in the engine compartment. The exhaust fan could be running by default whenever the engine runs as well.

I know I'm missing something. It just seems the water cooled system comes with many dangerous possibilities.

Lastly why not a closed system for cooling the engine? Or is that just not done? Seems safest IMHO.

Remember I am asking questions I already know are stupid in some form or fashion. I just gotta find out what the answers are.

thanks

 

[nlain]

Re: Who knows the most about sea ray exhaust systems?

Hey, if you do not know then it is not a stupid question, now if you ask the same one over and over then someone will get you.

Not 100% sure on why water cooled but my guess would be too much heat in the engine room, you can lay your hand on the water cooled exhaust versus a system running 1300 to 1800 degrees in the engine room, heat the air that much and your engines would lose power due to hot thin air, gas would boil in the lines, also too much metal to put in an engine room without flex joints, you would probably be starting fires with that heat, hence the water cooled exhaust and the rubber sections in the exhaust.

There are closed cooling systems for these engines, they use a heat exchanger that has raw water run through it to cool the engine water and you still have a water cooled exhaust.

The industry is working on catalytic converters for marine engines now and one of the things they are having to fight is heat in the engine compartment.

I do not know if my answers are 100% correct but they make sense to me.