Gardner 6LW Water Cooling Circuit

[Steve.Sharratt]

Hi,

I have a 6LW in my boat and it is fresh (closed) water cooled system with a raw water cooled heart exchanger. I recently decided that I should flush the cooling system but (and I am probably missing something obvious) but I can't quite figure the setup. I have the Gardner centrifugal water pump fitted and I am able to drain through its drain cock but where is the fill point? I have an expansion tank sitting above the engine and I expected to see it drop as I drained off at the pump. It didn't. I assume that the expansion tank will hold until the thermostat kicks in but (and this is my question) how do I refill the engine with coolant if it is closed off?

I have all the manuals but the cooling section doesn't really help.

Cheers

Steve

 

[scottie]

Is an expansion tank normal with raw water cooling?

 

[Steve.Sharratt]

Correct. Raw water passes through a heat exchange and is ejected through the exhaust. The expansion tank is connected through the closed portion of the cooling system (per an normal engine and radiator set up). I am looking to drain the closed engine portion.

 

[scottie]

It’s actually not raw water cooled then which refers to an engine that has raw water with no heat exchanger

 

[burgundyben]

Thermostats usually have a small hole in them to allow draining and refilling to work.

Are you sure the pump you drained is the one you think it is?

 

[Steve.Sharratt]

I am certain it is. Perhaps the thermostat drain is blocked.

 

[scottie]

Try mailto:info@gardnermarine.com
tel:+44(0)1227 20719630

 

[Assassin]

As stated above, the thermostat has a small hole drilled into it and water should drain through it even if it is slowly.

Find all your water pipes and remove the upper end of the pipes and fill through one of them, as water comes through the pipes simply refit them and continue filling.

You clearly have an air lock and possibly an aftermarket stat fitted and it would be prudent to check to see if it has got a hole in it and that it hasn't become blocked while your system is drained, and filling the engine from the bottom blows all the air out of the open pipes and removes most of it, and I would fill it with water first and run the engine and check to see if it runs at the correct temperature before adding anti freeze.

If your drain cock is the type with a valve on then connect a pipe to this as this is guaranteed to fill the engine from the bottom.

I would also be tempted to use a cooling system cleaner on it as these engines take a lot of abuse over the years and they get their internals heavily silted up.

 

[Steve.Sharratt]

Thanks Assassin - I will be in the engine room today so I will start pulling hoses off and see what happens. A good tip to fill through the drain valve - that could be a possibility and I will also look into a cleaner. I have some coolant to add afterwards but didn't consider a flushing product.

Cheers

Steve

As stated above, the thermostat has a small hole drilled into it and water should drain through it even if it is slowly.

Find all your water pipes and remove the upper end of the pipes and fill through one of them, as water comes through the pipes simply refit them and continue filling.

You clearly have an air lock and possibly an aftermarket stat fitted and it would be prudent to check to see if it has got a hole in it and that it hasn't become blocked while your system is drained, and filling the engine from the bottom blows all the air out of the open pipes and removes most of it, and I would fill it with water first and run the engine and check to see if it runs at the correct temperature before adding anti freeze.

If your drain cock is the type with a valve on then connect a pipe to this as this is guaranteed to fill the engine from the bottom.

I would also be tempted to use a cooling system cleaner on it as these engines take a lot of abuse over the years and they get their internals heavily silted up.

 

[Tamar]

Has it a remote water tank,I used to look after two 4lws and they had a header tank each.

 

[Steve.Sharratt]

Yes. it has a header tank (or expansion tank) that is mounted on the bulk head above the engine. This is fitted with a standard radiator cap and is my usual fill point. When I drained off at the water pump, the tank level didn't drop as expected. I ran the engine for some time and the temp gauge barely moved (normal until I actually drive the boat). The header tank water did start moving as the water heated but it didn't seem to drop.

Has it a remote water tank,I used to look after two 4lws and they had a header tank each.

 

[Tamar]

Sorry,still getting to grips with editing. My deleted message said our engine's used a common open header tank, I could isolate individual engine's and drain down the system to flush it out. I have a box of Gardner spares if you ever need something.