Volvo D12 800 - coolant overflow in bilge

[Scubaboy79]

Hello all,

I’m after some advice in relation to an issue I’m having with my D12 800 engines.

Despite the coolers/heat exchangers having been cleaned and the engines running at a steady 80 degrees, I’m getting a small amount of coolant in the bilge which seems to run down the transparent plastic tube which runs from the coolant tank filler to the bilge.

This happens if the coolant is filled up so I can see the coolant in the spyglass (which shows the coolant level). If the coolant is below the level of the spyglass (but still full enough that my finger touches the coolant if I unscrew the cap and put my finger into the reservoir) then I don’t get any coolant overflow into the bilge.

This issue happens on both engines.

Is it that I’m overfilling the coolant and as the boat rises onto the plane and the coolant expands as it heats up, it is overflowing? In which case, should I keep it at its current level (albeit that means no coolant in the spyglass) or might there be a more serious issue? I’m not getting any engine alarms.

Any advice would be very welcome!

 

[TK Blue MAX]

Our Targa 52 with D12 engines did exactly the same, we just left them at the bottom of the filler tube and they never overflowed again, they take a lot of coolant so wouldn't have thought a litre or so would make any difference, but just check regularly until you are confident they are not dropping any lower

 

[Scubaboy79]

Our Targa 52 with D12 engines did exactly the same, we just left them at the bottom of the filler tube and they never overflowed again, they take a lot of coolant so wouldn't have thought a litre or so would make any difference, but just check regularly until you are confident they are not dropping any lower

That’s really helpful to know - thank you.

 

[DAW]

With the engines cold, the coolant level should be at the bottom of the filler tube about 5 cm/2 inches below the bottom of the filler cap. It should be high enough to create a ”seal” at the bottom of the tube, but not all the way up the tube itself. The system contains 60L of coolant, so a small loss shouldn’t cause any problems.

I had the same problem on a previous boat with D12-715 engines. Now I have D13-900s and there is no spyglass/reservoir with min-max to check. You just fill to the bottom of the filler tube and monitor by removing the pressure cap to check when the engines are cold.

 

[dustywings]

Yes exactly the same as described above by others with our D12 715s. I got twitchy at first as the coolant is so bright, it does shout at you in the bilge. Same solution just don't fill too much.

 

[Scubaboy79]

Thanks everyone! As @dustywings says, when you see a pool of green coolant in the bilge it is somewhat alarming. I shall be more parsimonious with my filling in the future.

 

[Portofino]

Too stronger concentration of ethylene glycol = greater expansion. It blows off .

A lower concentration ie more water will get it in the sight glasses .

6: Adjust for antifreeze. Solutions of propylene or ethylene glycol have higher coefficients of expansion compared to water. The higher the concentration of antifreeze the greater the expansion volume required. The increase in volume for water heated from 60 to 180F is about 3%. The increase in volume for a 50% solution of propylene glycol heated from 60 to 180F is about 4.5%. This higher expansion rate should be accounted for when sizing tanks for applications where glycol-based antifreeze solutions are used.

But a litre or so in 60 as others have said means don’t worry .

 

[38mess]

Put a plastic bottle at the end of the tube, my Perkins does this from time to time and I just put it back in, saves wasting it in the bilge

 

[Scubaboy79]

Too stronger concentration of ethylene glycol = greater expansion. It blows off .

A lower concentration ie more water will get it in the sight glasses .

6: Adjust for antifreeze. Solutions of propylene or ethylene glycol have higher coefficients of expansion compared to water. The higher the concentration of antifreeze the greater the expansion volume required. The increase in volume for water heated from 60 to 180F is about 3%. The increase in volume for a 50% solution of propylene glycol heated from 60 to 180F is about 4.5%. This higher expansion rate should be accounted for when sizing tanks for applications where glycol-based antifreeze solutions are used.

But a litre or so in 60 as others have said means don’t worry .

Thank you. I just use the Volvo pre mixed stuff.

 

[Scubaboy79]

Put a plastic bottle at the end of the tube, my Perkins does this from time to time and I just put it back in, saves wasting it in the bilge

Good tip!

 

[jrudge]

My d12 are full of coolant and don’t do this.

I have had to replace on cap. I would try replacing one cap ( they carry a Volvo price tag !) and see if that helps.

 

[Scubaboy79]

My d12 are full of coolant and don’t do this.

I have had to replace on cap. I would try replacing one cap ( they carry a Volvo price tag !) and see if that helps.

Worth a try. Duly ordered…

 

[Portofino]

Do you D12/13 guys have “ expansion tank pressure “ monitoring? Can see it on a screen ?
This indicates duff caps , as it drops or can’t achieve .

As an aside with MAN s the caps are a two yearly change out part , there are two on each tank and I carry spares .
As a short cut to figure out which ones gone you can place a sheet of thin plastic film ie a single sheet of supermarket bag over the hole and trap it with the cap . This temporarily seals it = until you get a new cap .Stops leaks .Remember there’s another a second at the other end to blow if needs be .

But even with just one it’s a helpful diagnostic procedure attempting to figure out if it’s the cap in the first place .

Also another interim or permanent fix ( sometimes works ) is remove it turn the rubber seal , grease it lightly and return the cap .What you are doing here is mitigating the seal getting a set / squished with time and starting to leak .
Its the fact the rubber deforms with time is the reason they are serviceable parts in a arbitrary 24 month cycle .

Food for thought guys .

 

[DAW]

There is nothing on the Volvo Penta service protocol for the D12/D13 regarding routine change of the caps. I replace them when the heat exchangers are disassembled for cleaning and coolant changed, which for the D13 is every 48 months.

With the D13 you can configure the VP Glass Cockpit to allow you to continuously monitor coolant pressure, or display the information on a networked MFD. There is also a low coolant pressure alarm.