Coolant leak in cold temps?

[C&C32]

Hi
I live in Toronto Canada. In the winters we can drop to -20C at certain times. I winterize the A4 with automotive glycol antifreeze each winter. Raw water cooled motor.
I run a dry bilge all year and never have any water dripping during the regular temperate times of year. But when checking my bilge this week the is a few cups of antifreeze in it. We had a cold snap last week and after this drop in temp is when I saw the pool of coolant.
Same thing happened last year when temps dropped well below freezing. So last year I changed all water hoses on the motor.
When inspecting the motor and dusting the parts with talk to trace a leak only suggestion is it is coming from around the top of water pump or in that area.
I see no cracks or loose connections . Its a tight fit in my engine bay so its had to trace the leak.
Its a mystery that has reappeared from last year at same time of year. Im at a loss.
Any suggestions?
Thinking of trying a new water pump as maybe the seals are going ??? And the cold allows the fluid to leak?

Thanks
Cheers

[Mo]

Did you use pre-mix antifreeze or concentrated antifreeze.

I'm sure you know this but concentrated antifreeze has to be mixed or it gels. That usually happens around -20 or more. When it gels up it spreads out, takes up space of air in the system etc and if there's a small leak or vent it may come out through there.

Here a little note: This is generally the ballpark for all automotive antifreeze.
1. "when you create a 50/50 mixture using water and ethylene glycol, the boiling point rises to 223°F (106°C) and the freezing point lowers to -35°F (-37°C)".
2. "pure ethylene glycol freezes between 0 F (-17C) and minus 5 F (-20C).

Metal contracts in severe cold. Different types of metal contract at different rates as well...ie bronze, cast etc...so maybe as little drip. I had a dump truck with a Cat Diesel that leaked out the front of the engine near the water pump in cold weather when parked. When started the leak stopped as it heated up....that would always put a puddle on the ground. A small amount of antifreeze is sort of like blood....usually looks worse than it is.

Have a look at your strainer as well and ensure no crack in it.

Hope that helps.

[C&C32]

Thanks for the info.
I do run a mixed coolant. And will fully inspect the strainer and the water muffler.
cheers

[paulw]

Hello!

I have a rebuilt A4, the plumbing is such that the raw water goes directly into the engine where the plate is, it doesn't use the thermostat. The engine runs at 120 F.

What is the reduction in MPG, does anyone know??

Also, is the chance of condensation a big problem if the engine runs at this temp? I sail in San Francisco Bay.

Thank you.
Paul

[ndutton]

paul, can you please provide an overall picture of your engine?

[sastanley]

oh boy...two different problems in one thread.

Might need to get paulw to start his own thread.

C&C..I would rebuild/replace the water pump. It has a weep hole in case the seals fail to not let oil or water in the wrong direction.