2000 340 Sundancer exhaust

Carter,

Thanks. I have the smaller 7.4l engines and they appear to be OK with the logs. I recently read in a prior post that the horizons have the potential issue on this year boat.
 
Larry said:
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 basically 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 supposedly 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....
Click to expand...
Larry Sorry to beat a dead horse.
The boat I am looking at has Merc 350 in a 2001 310 DA not horizon 380 is this problem with the 350CI or just the bigger engines, when I talk to the owners mechanic he said he does not know what I am talking about but thinks it has the drum style mufflers not the log style. Just want to be sure I am not blowing smoke on this guy. The boat has 500 hrs and seems to run good.
 
TerryDes said:
Larry Sorry to beat a dead horse.
The boat I am looking at has Merc 350 in a 2001 310 DA not horizon 380 is this problem with the 350CI or just the bigger engines, when I talk to the owners mechanic he said he does not know what I am talking about but thinks it has the drum style mufflers not the log style. Just want to be sure I am not blowing smoke on this guy. The boat has 500 hrs and seems to run good.
Click to expand...

TerryDes,

Yes, there are issues with the 350's in the 310's (V drives only), they all had water intrusion issues with the "log" design exhausts. If the boat you are looking at has the lift type (pot shape) mufflers and is a 2001 it was retrofitted allready, which is good. I can't stress enough how important it is to still do a compresion test on both motors to verify that they don't have any lingering effects from the water issues in there past. This was a massive problem on all the 310's and on the 330 and 340's with the Horizon motors
 
jim_m5 said:
Carter,

Thanks. I have the smaller 7.4l engines and they appear to be OK with the logs. I recently read in a prior post that the horizons have the potential issue on this year boat.
Click to expand...

Jim,

Why does your signature say you have the Horizon's, but you say you have the smaller 7.4's? All the 7.4 Horizon's were the 380hp and had the water intrusion issue with the "log" style exhaust, don't let anyone tell you otherwise.
 
TerryDes -

The first boat we looked at was an '01 310 with small blocks - it had both engines replaced at 7 hours due to the horizontal log muffler issue...After the engine change, they put water lift mufflers in...
 
Larry said:
TerryDes,

Yes, there are issues with the 350's in the 310's (V drives only), they all had water intrusion issues with the "log" design exhausts. If the boat you are looking at has the lift type (pot shape) mufflers and is a 2001 it was retrofitted allready, which is good. I can't stress enough how important it is to still do a compresion test on both motors to verify that they don't have any lingering effects from the water issues in there past. This was a massive problem on all the 310's and on the 330 and 340's with the Horizon motors
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Thanks again Larry, we have negotiated a compression test if I decide to take this boat, this is of coarse after we confirm they are lift type mufflers.
Great help thanks
 
Hi Larry, I just want to be clear, I have just purchase a 340 with 7.4 litre MPI's, am I correct thinking there is no problem with these?

Also, I have just posted in the general sport cruiser area re an alarm problem, would you mind having a look please and see if you can put anu light on the situation.

Many thanks,

Jon
 

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Larry said:
Got it!
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Hi Larry, etc -

I've just found this thread as I researched an issue my mechanic mentioned for me to be aware of. My 2000 340 Dancer has the 7.4 Horizons. I've just shy of 600 hrs on each engine and regardless of the low hours, I've been cautioned about the potential for a valve job...irregardless that my engines had the updated 3" risers from the factory. My manifolds elbows and risers were replaced in Spring of 2015 and the risers are showing wear already with approx 150 hrs since the install. (I don't know that the latter is relevant at all)

My question is, how, if at all, does one get ahead of needing a valve job if there are no particular signs or any issues from a performance standpoint? I saw earlier in this thread a compression test can be performed. Thoughts? Thanks in advance.

Mike
 
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