Ajeno

Ok. I've discovered the leak on the main radiator. Got another one, and replaced it. This what I've done.... Filled the rad with water first before connecting the pipe from the extension tank. Then connected that pipe, and continued to fill up the extension tank until it required no more water. I started the engine up for about 30 seconds. the re-filled the extension tank. I kept doing this until no more water was required. As far as Im concerned it's all done. But, should I do something else before I drive it properly? should I put anti freeze or something in it too? Do I need to bleed anything first? and if so, how do I do that? Im worried I might damage the water pump.

Help? lol

AudiMick

You need Audi/ VW G12 coolant or equivalent. Don't use generic green coolant.

Bleed the heater core at the hose on the firewall.

Your thermostat has probably not opened yet , once it opens more coolant will be required.

12vB5

You should not have pre-filled the radiator with water*. Instead you should have filled the system at the raised expansion tank (Or use a special expansion tank adaptor to prevent overflowing) first with with the full amount of coolant concentrate. Depending on your engine, you had to open one or two bleeder screws, plus you had to expose the bleeder hole on the heater core hose. Then you should have added slowly an equal amount of water.

With the engine running and the heater turned on all the way, at slightly elevated RPM (~2,500 RPM), you should have let the cooling system purge itself of air (expansion cap off). The bleeder screws needed to be closed as soon as coolant came out. You also had to touch the coolant hoses to make sure that coolant was really flowing. Sometimes and air pocket can prevent coolant flow, which requires more bleeding. The bleeder hole at the heater core hose needed to be observed and closed eventually. The expansion tank needed to be lowered (or the adaptor removed).

After screwing on the expansion tank cap, the car should have been test driven a few miles, looked for leaks and topped off with coolant as necessary.

*By pre-filling the radiator, you essentially did create an air pocket between the radiator and the expansion tank. That's not good, because an air pocket may prevent coolant from reaching the water pump right away. The water pump should not run dry at all.

It should also be coolant concentrate and not plain water that comes in contact with metal that is still "unprimed" by corrosion inhibitors.

Here is a picture of my shiny new radiator, which I installed when I was doing the timing belt a few weeks ago:

<a href="http://s4.photobucket.com/albums/y108/moribundman/timing%20belt%20and%20radiator/?action=view&current=DSCF7466s.jpg" target="_blank"><img src="http://i4.photobucket.com/albums/y108/moribundman/timing%20belt%20and%20radiator/DSCF7466s.jpg" border="0" alt="Photobucket"></a>