Question about changing raw water cooling to closed system on 15 year old boat

[maicoman]

I would like some of your opinions on the idea of changing to closed cooling from raw water.I have a 1998 305 TBI with an Alpha 1 leg.The exhaust manifolds and elbows have just been changed on this 222 hour engine which is moored in the summer in salt water.Do you all think that the damage that has inevidentially been done to the engine block,would not be delayed by this improvement at this point in time.I like the boat and would like to keep it for another 10 years or more.

 

[Silly Seville]

Re: Question about changing raw water cooling to closed system on 15 year old boat

I will preface by saying I am not a saltwater guy. However, I think there are some simple questions that must be answered to come to a reasonable conclusion.

1. Are those 222 hours ALL saltwater hours?
2. How were those hours accumulated...i.e. in 2 years or 13?
3. Did the engine ever get flushed with sweetwater periodically during the season-if so how often and consistently?
4. Have you owned the boat since new and can vouch for the above?
5. Have you been given an estimate by several reputable shops on the total cost to retrofit this system?

There is a reason why native Midwestern boats are highly prized on the east and gulf coast, and conversely, why coastal boats languish in dry dock for sale forever, for a fraction of the price the same vessel that's documented as a "freshwater only" craft.

 

[Don S]

Re: Question about changing raw water cooling to closed system on 15 year old boat

Manufacturers recommend not installing a closed cooing system if the boat has been used for 125 hours or 1 year whichever comes first. After that, you could plug up the tube bundle with rust and corrosion, and that side can not be cleaned out.
Having said that, I have installed systems for customer with many years on their engines. Had about a 50% failure rate. Even after repeated flushings with salt away.

 

[tpenfield]

Re: Question about changing raw water cooling to closed system on 15 year old boat

I have a Mercruiser 7.4L that has been 20 years in salt water and I recently unloaded the block of iron and sand sediment. With yours at 15 years, what's the point in going to FWC? The damage is done. As Don says, it will be chucking iron flakes out for the rest of its life. If you ever do a new long block, that is your opportunity.