Fresh water cooling system

S

Sea Señor

Member
Aug 31, 2021
55
South shore, Long Island NY
Boat Info
2010 280 Sundancer
Engines
Mercruiser 350 MAG MPI w/bravo 3 drive
Hi all, I have a 2010 280 sundancer with a mercruiser 350 mag mpi raw water cooled. Just had the manifolds and risers done in the spring. Is it worth installing a fresh water cooling system? Does it help extend life to the manifolds and risers? Someone recommended I do that. Haven’t spoke to the mechanic at my marina about it yet. Wanted to see if anyone has done that and if it’s worth it. Thanks
 
You would still have raw water through the risers and manifolds.
 
You probably have too many hours on the engine at this point. I've done it on my current boat and my last boat but both came from fresh water. The rule is 300 hours on a fresh water engine and 150 hours on a salt water engine. My RWC to FWC conversion does include the manifolds but not the risers.
 
Brite Idea said:
You probably have too many hours on the engine at this point. I've done it on my current boat and my last boat but both came from fresh water. The rule is 300 hours on a fresh water engine and 150 hours on a salt water engine. My RWC to FWC conversion does include the manifolds but not the risers.
Click to expand...
I have 205 hrs on my motor
 
I'm not an expert but your 12 year old salt water engine may already have too much salt in the cast iron to be able to flush out. That be said why not add a flush kit and do the salt away flushing after you use the boat?
The FWC kit from Merc was almost 4K and the hose kit another 700 so two years ago 5K in parts per engine. I did it because the boat I bought came from a lake with 270 hours on it.
I ended up having to do manifolds and risers this year anyway so I'm not sure if adding FWC will make your manifolds last forever just longer?
 
I converted my new to me 1995 330DA to full system cooling, manifolds and risers, when I purchased it, though the long block engines had less than 5 hours on them so that was the right time to do it. I don't think I would do it at this point if I were you. The return is probably not worth the investment. That said if it makes you feel good, which is mostly why I did it, knowing raw water wasn't in my engine blocks, go ahead and do it.
 
Brite Idea said:
I'm not an expert but your 12 year old salt water engine may already have too much salt in the cast iron to be able to flush out. That be said why not add a flush kit and do the salt away flushing after you use the boat?
The FWC kit from Merc was almost 4K and the hose kit another 700 so two years ago 5K in parts per engine. I did it because the boat I bought came from a lake with 270 hours on it.
I ended up having to do manifolds and risers this year anyway so I'm not sure if adding FWC will make your manifolds last forever just longer?
Click to expand...
My mechanic told me it wouldn’t make much of a difference. Thanks
 
While in my book and climate yes it would make a difference. It was one of the things on my list when I found Full House and I still love this boat. In my area it’s a great plus upon resale I hope.

Would I spend the money to add the system, no.
 
dwna1a said:
While in my book and climate yes it would make a difference. It was one of the things on my list when I found Full House and I still love this boat. In my area it’s a great plus upon resale I hope.

Would I spend the money to add the system, no.
Click to expand...
My mechanic said if you use your boat a lot it doesn’t make much of a difference. It’s the boats that sit for long periods that lose the maximum life of their manifolds and risers. I agree with that. The more you use your boat the less problems you have. I use my boat a lot
 
The plate / gasket the sits between the riser and it’s manifold is the weak point for the system. Sediment settles on the plate causing it to deteriorate and then fail. In my area we pretty much always tell the new boaters to let the engine run and flush itself out.

My manifolds were changed the year I bought the boat. That was about 6 years ago. So far no issues. The key, besides regular maintenance is the water I’m in.

I do agree with your shop, boats need to run and it’s systems need to be stressed.
 
Brite Idea said:
I'm not an expert but your 12 year old salt water engine may already have too much salt in the cast iron to be able to flush out. That be said why not add a flush kit and do the salt away flushing after you use the boat?
The FWC kit from Merc was almost 4K and the hose kit another 700 so two years ago 5K in parts per engine. I did it because the boat I bought came from a lake with 270 hours on it.
I ended up having to do manifolds and risers this year anyway so I'm not sure if adding FWC will make your manifolds last forever just longer?
Click to expand...

Any recommendations on a flush kit for a 350?
 
I put brass garden hose fittings on top of my strainer lids. Close seacock, and flush with fresh water. Also great for winterizing!!

You can buy them on Amazon.com and have a machine shop install them.
 
You must log in or register to reply here.

Forum statistics

Threads
113,172
Messages
1,427,867
Members
61,086
Latest member
MrWebster
Back
Top