Raw Water Cooling Corrosion

[tinkicker0]

Recent thread had me wondering. How long does a saltwater cooled engine block generally last before corrosion eats through the cylinders?

Reason I ask is that my motor is raw water cooled and has generally been used in freshwater as it is now, so not too concerned, but it has had about 5 years use in the sea at some time in its past. Of course I replaced the manifold and also had to replace the circulation pump but if I were ever to return her to the sea, how long could I expect.

Mercruiser 3.0l

 

[[2068]]

It's not normally the block that dies, but the manifolds and risers.
If the manifolds and risers are changed every 5 years, there is no reason why the block shouldn't continue. There are plenty of 15 yr old plus petrol engines out there still running.

 

[Poignard]

My directly cooled engine is 30 years old and has always been used in sea water.

I replace the anode every year because the existing one is decayed, which shows it's doing it's job.

 

[prv]

There are prehistoric lumps in old sailing boats still going after many many decades.

I keep an eye on the anodes in my 2GM20; they're wearing away at a moderate pace and as long as I change them when required I expect the block to last indefinitely.

Pete

 

[scottie]

It ironic that with a engine designed for a pickup truck that the first part part to suffer from corrosion is the marinised exhaust system.

 

[Poignard]

There are prehistoric lumps in old sailing boats still going after many many decades.

Yes - and I still have all my own teeth.

 

[GrahamHR]

There are prehistoric lumps in old sailing boats still going after many many decades.

I keep an eye on the anodes in my 2GM20; they're wearing away at a moderate pace and as long as I change them when required I expect the block to last indefinitely.

Pete

The American 3.0 / 4.3 V6/ 5.0, 5.7 V8 engines etc don't have an anode except if there's a heat exchanger fitted like mine ( why not, who knows !)

 

[prv]

The American 3.0 / 4.3 V6/ 5.0, 5.7 V8 engines etc don't have an anode except if there's a heat exchanger fitted like mines ( why not, who knows !)

Probably because they were built for pickup trucks?

Pete

 

[GrahamHR]

Versions of those engines fitted to pick up trucks were cooled by an antifreeze/ water mix that contained corrosion inhibitors; a bit different to salt water !

Why do VP fit anodes to some of their raw water cooled engines and not to others? Cost I suppose, coupled with their biggest market for such petrol engines being.for boats used in fresh water; those same engines better suited to salt water use with "closed" cooling do contain anodes.