Drain/Refill Cooling Water 2LW

[mark99]

How do you do this?

 

It's got a remote skin tank, gearbox oil cooler in line, calorifier circuit and a <non pressurised> header / expansion tank.

 

Thanks.

[andywatson]

Without seeing your system here's my advice:

Get acess to as much of the cooling system as you can to familiarise yourself before you start

 

Start at the back / lower end of the keel cooling tank where you will hopefully find a drain plug, or better still, a valve and hose tail which will allow you to drain / pump out the coolant with minimum mess.

-If you have only a plug, unscrew it and get a hose tail on it ASAP - or let the lot go and pump it out.

(fit a valve before re-filling so you'll be in good shape next time)

 

If you haven't got either of the above maybe you can find a drain valve tee'd into one of the hoses.

 

If you don't have that you need to disconnect the lowest hose and drain / pump it out.

Remember the coolant will come at you both ways (!)

 

You might need to suck the coolant out of the skin tank with a vacuum extractor if you are really unlucky.

 

When re filling the system (after installing some kind of drain valve as above) be prepared to bleed air from high spots in the system and possibly the calorifier coil, especially if it's a horizontal one.

Expect to hear a lot of gurgling as you fill up.

 

You might have air bleed points on the top of your skin tank if both inlet and outlet are at the bottom..

 

When you've done run the engine and bleed air again as required and all pipes get hot.

 

 

A refinement worth considering:

I've built my boat with drain on the back/ bottom of the skin tank and can pump it out without any mess into plastic drums. Rather than fill it at the header tank I pump it back in at the drain point ( using a small rotary drill pump) thus filling it from the bottom up which reduces the chance of airlocks.

Edited October 27, 2013 by andywatson

[mark99]

snip

 

You might have air bleed points on the top of your skin tank if both inlet and outlet are at the bottom.

Thanks.

 

Yes there is an air bleed nut in the top of skin tank. Not sure about a drain - will have a better look when next on board.