Bukh anode and oil pipe queries

[Poignard]

Contact Albert or Norman on 01202 668840 - goodness knows what will happen when they retire.

Maybe they are like their engines - they'll last forever

 

[Scotty_Tradewind]

indirect.

Direct takes seawater through engine to cool it (directly).
Indirect takes in seawater but it's used to cool the heat exchanger,which in turn cools the engine using a separately pumped circuit of captive coolant.

The captive coolant in the indirect system can have additives that look after the engine, which the direct seawater system cannot.

that's an easy to understand description.... thanks
S.

 

[cliff]

I spent ages witth a marine engineer looking for an anode and cannot see one.
Mine is a Bukh 24. Where is it?

S.

Rear of the block RHS looking towards flywheel end, just above rear casing

 

[LittleSister]

So as my engine is indirect cooled I don't need an anode? (And just wasted a weekend!)

If not, why not?

 

[soreknees]

So as my engine is indirect cooled I don't need an anode? (And just wasted a weekend!)

If not, why not?

Indirect cooling uses freshwater - saltwater with direct cooling

 

[LittleSister]

So as my engine is indirect cooled I don't need an anode? (And just wasted a weekend!)

If not, why not?

Indirect cooling uses freshwater - saltwater with direct cooling

I know that, but why would it remove the need for an anode?

 

[alan_d]

I know that, but why would it remove the need for an anode?

With direct (or raw water) cooling the water flowing through the waterways around the engine block comes from whatever the boat is floating on (salt or fresh) and is returned to it immediately afterwards. Indirect cooling is like what happens in a car; the water/antifreeze/corrosion inhibitor mixture around the block is passed through a heat exchanger (like a car radiator) where it is cooled by raw water from the outside and then recirculated to the block. With indirect cooling you can have corrosion inhibitors in the coolant because it is recirculated and retained, with raw-water cooling you are using different water all the time so you have to do something else to stop your cast iron engine rusting away, hence the engine anode. Heat exchangers are usually made from corrosion-resistant materials so you don't need an anode to protect them.

 

[LittleSister]

With direct (or raw water) cooling the water flowing through the waterways around the engine block comes from whatever the boat is floating on (salt or fresh) and is returned to it immediately afterwards. Indirect cooling is like what happens in a car; the water/antifreeze/corrosion inhibitor mixture around the block is passed through a heat exchanger (like a car radiator) where it is cooled by raw water from the outside and then recirculated to the block. With indirect cooling you can have corrosion inhibitors in the coolant because it is recirculated and retained, with raw-water cooling you are using different water all the time so you have to do something else to stop your cast iron engine rusting away, hence the engine anode. Heat exchangers are usually made from corrosion-resistant materials so you don't need an anode to protect them.

1) I don't think an anode will provide any resistance to rusting. That's oxidisation, I believe. As I understand it anodes avoid the harmful effects of electrolytic action. (The sacrificial anode depletes instead of critical parts depleting.)

2) If indirectly cooled engines don't require an anode, for whatever reason, why does my indirectly cooled Beta engine (in my other boat) have an anode that certainly does deplete?

 

[vyv_cox]

1) I don't think an anode will provide any resistance to rusting. That's oxidisation, I believe. As I understand it anodes avoid the harmful effects of electrolytic action. (The sacrificial anode depletes instead of critical parts depleting.)

2) If indirectly cooled engines don't require an anode, for whatever reason, why does my indirectly cooled Beta engine (in my other boat) have an anode that certainly does deplete?

1) Yes, the anode corrodes preferentially but it is protecting the iron of the block, in exactly the same way as an anode protects a steel hull. There are very few other metals in there, thermostat and maybe a temperature sensor, not much else. They are fairly corrosion resistant anyway but are protected by the iron of the block. Since this is vast by comparison it is harmless.

2) No idea. No cars have anodes, for the reasons that alan_d has given. Provided you are using anti-freeze solution in good condition there is no need for an anode. Is the anode on the seawater side of the heat exchanger? There can be quite a cocktail of metals in there, in which case an anode protects against galvanic corrosion. Some engines, e.g. Yanmar, have heat exchangers that are corrosion resistant and need no anode.

 

[Poignard]

1

2) If indirectly cooled engines don't require an anode, for whatever reason, why does my indirectly cooled Beta engine (in my other boat) have an anode that certainly does deplete?

I'm not familiar with that engine but might it be that the anode is in the heater exchanger, ie in contact with seawater?

 

[Poignard]

1) Yes, the anode corrodes preferentially but it is protecting the iron of the block, in exactly the same way as an anode protects a steel hull.

Is it true that the anode must be in electrical contact with the block for it to work?

The reason I ask is that when BUKH owners have difficulty removing corroded anodes they sometimes just knock them through into the cylinder block.

Do those anode remains carry on working as anodes and protecting the cast iron? If they do, why not save the expense of buying anodes from BUKH (or ASAP) and just drop in a few pellets of zinc each year?

 

[LittleSister]

I'm not familiar with that engine but might it be that the anode is in the heater exchanger, ie in contact with seawater?

No, its in the freshwater side of the heat exchanger.

 

[LittleSister]

1) Yes, the anode corrodes preferentially but it is protecting the iron of the block, in exactly the same way as an anode protects a steel hull. There are very few other metals in there,

Maybe the anode is there to protect from dezincification the brass nut that holds the anode!