Benefit analysis for fresh water cooling

[williamg]

So I bought an old boat with an old A4 that seems to run well enough. It has raw water cooling. How do I decide if the engine is in good enough shape to warrant putting in expensive (for me at least) fresh water cooling?

[Kelly]

Hello Williamg,

I can only speak in general terms but will repeat what I've been hearing on this subject over the past few years.

Fresh water cooling means more peace of mind for your engine block. Raw water running through the block means much more possibility of internal corrosion and blockage. The salt in the water can precipitate and collect in the cooling passages. Over time this can reduce the cooling capacity and result in over-heating (or worse).

Standard maintenance for raw water-cooled blocks includes acid flushing to remove some of the deposits. Was this done regularly on your A4? Do you know the internal condition of the block and the cooling passages? The fact that the engine is running well is a good sign but how much do you know about the true condition?

Fresh water cooling means adding another water pump, heat exchanger and associated plumbing- more systems to monitor and maintain. But I find it nice to know that coolant is circulating in the block and not salt water straight from the ocean.

You have to weigh the investment vs. return for your situation but I think that fresh water cooling will extend the life of your A4.

I'll let others add more technical information and personal experience.

Good luck!

Kelly

[JimG]

This may be contrarian advice, but if it's an older engine and is running fine, I'd leave it be, unless you just moved the boat from a lake to the ocean. Something about sleeping dogs...

My boat engine was supposedly rebuilt in 1994 (that's what the receipt that was in the log says), and the boat was in San Diego bay for 10 years, then I bought it and moved it to S. Oregon. It's never had any acid flushing, winterizing, or other maintenance since 1994 (the PO^2 hardly used the boat), although I have changed the oil once in two years and replaced the carb gasket. Luckily for me, my dock in Brookings OR is constantly doused with fresh river water. Most of our races end at low tide, so despite the salt water exposure during the motor out to the course and back, it's been freshened by the time I shut her down. No barnacles either! Of course there's the trade off of crappy sailing conditions.