Join Date: Apr 2012
Location: Wexford, Ireland
While you're working on the header tank have a look at the 3 sealing rings, one below the steam valve, one at the level probe and one at the screw on cap. I recently refurbished the header tank on my 1979 Silver Shadow 11 and found that all these rubber sealing rings were perished. I had been losing a little coolant via the level probe o-ring. I cleaned the inside of the header tank using a solution of hot water with citric acid and let it sit for a few hours. It helped to remove some of the crud from the header tank but not all of it. The header tank may look rusty on the inside but usually the brown appearance is merely baked on deposits from the coolant. The radiator shell is brass but I think that the header tank is actually made of steel. There's a baffle plate inside the header tank designed to stop the coolant from swishing around and giving a false level reading when cornering which can cause the low coolant warning lamp to illuminate. This baffle can become detached as was the case with my car but my local radiator repair shop managed to silver solder it back into place through the filler cap hole and didn't have to prise the header tank open to do the job. When fitting a new gasket between the tank and the steam valve cover plate I simply sanded the surrounding area with very fine sand paper. I placed the cover plate in position without placing the bolts on and stuffed a cloth into the filler cap hole and the level probe hole and spray painted the top of the header tank with grey primer aerosol, allowed to dry and then top coated with black spray paint aerosol. It turned out like new. I then fitted the steam valve gasket, cover and screws, my screws were rust free and looked like new, if the old screws are rusty it would enhance the finished appearance by cleaning or replacing them.