This pipe has just split next to the small union nut into the cylinder head(due to corrosion) on my Series 3, fortunately at home, losing the coolant over the garage floor. I do have a good replacement manifold (Solex/Weber type) with a perfect pipe, and my first thought was to detach the pipe and fit it to the old manifold in situ, so I don't have to take both manifolds off. However, someone has partially undone the big union nut on the spare manifold a couple of turns, and the nut has then seized. I can't shift it with a normal spanner and I'm afraid to put too much force on it in case I strip the thread. I'm thinking that this union nut will be equally difficult to remove from the original manifold and the connection into the cylinder head also looks a bit nasty, and likely to snap off without too much force.

I can see the potential for this job to snowball into removal of the cylinder head to drill out the stump of pipe, so can anyone suggest any tips for solving this problem before I take a spanner to it and make things worse!? A possible bodge that occurs to me is to hacksaw the middle section out of the pipe and replace it with a bit of heater hose, provided there is enough undamaged pipe at the cylinder head end to form a connection.

Why is this bit of pipe made of steel (and therefore bound to corrode) when the unions are brass? Why not make the whole thing out of brass or copper, or just use a flexible hose?

Many thanks.

Steve (3234)