2000 340 Sundancer exhaust

B

bone354

Active Member
Oct 3, 2007
186
Great South Bay NY
Boat Info
2000 340 Sundancer
Engines
454 Horizon V Drives
I have 2000 Sea Ray 340 Sundancer with twin 454 Horizon FWC. It doesn't have the exhaust update. The engines have 500 hrs on them . I just purchased this boat and was planning on upgrading the exhaust myself. I was looking over the parts list for a 2002 340 Sundancer does anyone know if this exhaust would work with my setup or has anyone done this upgrade. Do I even need to do this upgrade since the engines have 500 hrs with know problems. Thanks Rich
 
Is the 'update' you are refering to the 3" or so extension that goes between the exhaust manifold and the exhaust elbow? I had a 2000 340 Sundancer with the 7.4 Horizon's.

For those that are not aware of the problem, there was an issue where seawater could backup into the exhaust and cause serious problems.

I would say with 500 hours your are either lucky, or your boat won't have that issue. Either way for what it would take to add the riser extensions I would do it.
 
I assume you are talking about riser blocks and the lift style muffler as the updates. I am curious if you have done a compression test lately as this is the only way to tell if you are suffering the affect of water intrusion. I would bet you will find that your exhaust valve seats are starting to rust and that your middle cylinders have lower compression. If you do a compression test and find solid compression in all cylinders, then I would be very surprised but somehow you skated around this very well documented Merc issue. I would expect you to need a valve job by now caused by water intrusion…


Sorry, don’t mean to sound like pessimist….
 
If you have 500 hours and they have not self destructed yet, you are lucky. A good marine gas engine is good for at least 1000 hours is properly maintained.

Check with Merc and see what they recommend for a riser lift to eliminate the problem.

WRT the exhaust update...I was at Saint Max today. I have the original style "log" exhaust. I have straight mufflers inline with the side exhausts and at speed, the exhaust goes underwater.

When the mufflers go bad, I shall go with one of CSR new sponsers who has figured out via physics how to muffle sound without restricting flow.
 
Thanks for info Guys. Greg do you remember what Riser Kit your old 2000 340 had 3" or 6" Thanks Rich
 
The riser blocks that you should have are the 3" ones, the risers by themself does not fix the problem. The problem that you have is the Horizon (380hp) motors have a valve overlap that causes a suction when the engine is shut down, any water left in the log mufflers have the potential of being sucked back through the exhaust into any open exhaust valves, this is seen mostly on the center cylinders as that is the easiest cylinders for water to get in being just below the elbow. The lift type mufflers basicly eliminates the problem of water getting sucked back in. This water intrusion problem is most prevalent on the Horizon motors due to there cam design. There was another thing that Merc was doing when they started to fix this problem and that was convert the cooling system to a full (exhausts too) cooling system which required changing thr heat exchanger to a larger capacity for the added cooling capability.

I have in my file all the drawings that Sea Ray and Merc came up with when they designed the "new" exhaust system, my boat was suposedly the prototype that they did it on in 2001, and they spent about $40K at that time in R&D (& new long blocks) on my boat.

Welcome to Merc engineering....
 
Mine had the 3" riser extentions, and it did have the 'log' style mufflers. I was told that was the only fix, that having the risers higher the water could not back up into the exhaust. I never heard that the pot mufflers was also part of the fix. Makes sense though if the cam has the overlap you mention.
 
This is a great thread. i bought a 2000 this summer. I did not know of the exhaust. How would I know if the 3" riser was added. :huh: Does anyone have a before or after picture?

Thanks
 
mquiet said:
This is a great thread. i bought a 2000 this summer. I did not know of the exhaust. How would I know if the 3" riser was added. :huh: Does anyone have a before or after picture?

Thanks
Click to expand...

First do you have the Horizon motors? or the standard motors? If you don't know how to tell the easiest way is do you have a plastic cover over the top of the motor? Or is it a black krinkle painted plenum with orange writing that says Horizon on them? The riser block goes between the exhaust manifold and the elbow, it is just a piece the raises the elbow up a little higher.
 
Larry.
I have posted under buying my first plane, I am looking hard at a 01 310 with mercruiser 350 engines.
The boat has 500 hrs do these engines fit into the same problem and if the mode was not done should I run for the hill while I still can. If the mod was needed and not done is it fair to think the engines valves have had some serious pre wear inflicted on them.Thanks for the great info.
 
TerryDes said:
Larry.
I have posted under buying my first plane, I am looking hard at a 01 310 with mercruiser 350 engines.
The boat has 500 hrs do these engines fit into the same problem and if the mode was not done should I run for the hill while I still can. If the mod was needed and not done is it fair to think the engines valves have had some serious pre wear inflicted on them.Thanks for the great info.
Click to expand...

The 310's had the same problem with the log style exhaust that was in there untill I think 02. I have not seen a 310 that didn't have new engines installed that had the log style exhausts, these were rectified by installing the lift type muflers (they look about the size and shape of a 5 gallon bucket). Run away if it has the log style exhausts! If it has the new exhausts make sure you have a compresion test done, and if good, you should be in ggod shape for a while.
 
Larry,

My boat is already wrapped for winter, but I seem to recall a black cover over the motors with the only writing being "7.4" I also think it was in white. Is this the standard? If so, is it ok?

Thanks again.
 
mquiet said:
Larry,

My boat is already wrapped for winter, but I seem to recall a black cover over the motors with the only writing being "7.4" I also think it was in white. Is this the standard? If so, is it ok?

Thanks again.
Click to expand...

If it is the black plastic cover and say's "7.4" you have the standard motors (Horizon's do not say 7.4 on them). with the standard motors you do not have a water intrusion problem, and are OK with the "log" style exhaust.
 
Thanks Larry, you just made my holiday season and spring.:grin: Now I just need to install some rod holders for light fishing with the kids and enjoy.
 
The 340 dancer is a popular boat any other owners have any experience with this problem or update please reply. Thanks Rich
 
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