Those owners who regularly flush out the cooling system will only be to aware of the inaccessibility of the cylinder block water drain tap. In particularly those with the Bentley models, which are fitted with twin carburettors, instead of the single unit fitted to the Rolls-Royce models will have found they are
at a disadvantage in respect of access.
The factory at one time did supply a drain tap key that greatly assisted the chore of opening the tap.
A sketch of the following key is shown below, a double end slot may be needed to accept a MkVI type tap. The key can be quickly made from a 14 inch (340 mm) long length of pipe 0.6 inch (15 mm) internal diameter and 0.8 inch (20 mm) external diameter. A length of steel electrically conduit pipe is ideal. At one end one slot 0.325 inch (8 mm) wide and 0.8 inch (20 mm) long will need cutting out with a hacksaw to accommodate the head and lever of the actual block tap. At the opposite end to the slot, four holes will need drilling at 90 degrees to each other some 15 mm centres from the end of the pipe. The holes sized to suit either the tommy bar contained in the car tool kit or some other suitable bar.
Provided the 14 inch length is not exceeded the pipe will fit over the head of the block tap and will not foul the one-shot lube tank if the tank is right hand side mounted. Inserting the tommy bar through
the holes drilled at one end of the pipe will then enable the owner to open the coolant drain tap.
It is advisable before trying to open the tap to remove the right hand under shield and tap the under side of the tap centre spindle upwards to release the tap taper from its seat. The taper main centre of the tap
is spring loaded.
For this operation a bar some 18 inch (450 mm) or so long will be needed, or a socket set long and short bars coupled together. The bar will only need striking lightly with a hammer to release the tap taper from underneath the car.
Failure to release the taper before trying to undo the tap may well result in the tap lever breaking off when pressure is applied through the tommy bar to the pipe.
After draining the coolant and closing the tap it is advisable to use the bar to lightly strike the top of the tap head, thus seating the taper tap onto its seat again.
Similar precautions need to be taken with the bottom radiator tap in respect of easing the taper before undoing the tap. This particular tap is made of brass and if the taper is not released before opening proceeds, breakage of the tap is guaranteed.
The accompanying images show a sketch of the key, which is also shown in position on the cylinder block drain tap on an R Type engine.
