2004-2006 Sundancer Exhuast Defects (300,320,340)?????

[sbednaz]

I have some serious problems with my 2005 320 sundancer Mercury engines over the last couple years. Most recently had the exhaust manifold blow out flooding the engine with salt water destroying the engine. We are Meticulous in maintaining our engines, flushing the engine with salt away for 15 minutes, then fresh water for another 15 minutes. After which we leave the seacocks closed to prevent any saltwater entering the engine. This is done after every use even if it is 15 minutes.

Despite this the engine is shot. Marine Max just told me to replace the engine, but i wanted to know the cause for furture reference. Another Mercrusier dealer told me that he had 5 sea ray boats this summer that had the same problem, all of which were around the same model years and similar models. Several months later several more sea rays had the same issues. After investigating the problem, they found that it was Sundancer models 300, 320 & 340's and the 2004-2006 years
that it was occuring with and that other boat manufactorers that were using Mercury engines were not having the same issues.

They have determined that it is a design flaw in the cooling systems design, but since it is corrision it is not covered by warranty.

I know of several people that have encountered this issue here, but wanted to check to see if anyone else has encountered the same problem.

 

[Stray Cat]

Were all of the failures salt water boats? Who is the THEY you refer to in your post...

 

[skolbe]

Do you have outdrives or V-Drives. I follow every post on the 320 and this is something that I have not read other post on. Also follow the 300 and 340 posts closely as well. Are the exhaust manifolds shot?

 

[sbednaz]

From our research it sounds like the majority of them are saltwater since that is where we are using it. They is the Two Marinas in North Carolina that have encountered a dozen of the them during the 2011 year. It has to due with the manifolds being shot because of a design flaw in the elbow of the exhaust system. I know about the corrision issues in Saltwater, but this has not been an issue with other year models or other mercury enigines in other manufactorers boats. The engines are all V drive. and it only occurs on the outboard side. This will be my second portside engine in three years, first was a factory manufactoring flaw, and this one is due to the manifold.

 

[Jimmy Buoy]

Sorry to hear of your problems.

You may want to do some research on Google. I recalled an article regarding Merc Exhaust Elbow design issues allowing water to reverse back towards the engine and it didn't take much searching for me to find it again...

http://www.michel-christen.com/ExhaustElbows.pdf

This article may be of help to you, but if not - Google can be a great resource!

 

[N369RM]

Would the Hy-tech Stainless Exhaust that inclused the risers take care of this problem in the future?

Ron Mason
1998 270 DA
7.4 Bravo III