For the non-purists who like to drive the cars and not worry so much about down time, Jim Alcorn has for a while been re-manufacturing Twin Cam water pumps with special machined shaft, a modern seal, and a modern sealed cartridge bearing which may be expected to last a lifetime (at least my lifetime).

For the purists who insist on staying original (or may be cheap like me), the original Twin Cam water pump may be rebuilt almost ad infinitum. In fact with the right parts in hand it can literally be done as a roadside repair. This is one of the more endearing features of the MGA in original form, being able to repair almost anything and drive on. The parts you might want to carry along to rebuild the Twin Cam water pump are:

1) 07008 Circlip
2) 07010 Distance Tube
3) 07011 Circlip
4) 07014 Key
5) 07016 Dust Cover, Front
6) 07017 Felt Dust Excluder, Rear
7) 07018 Dust Cover, Center
8) 07019 Dust Cover, Rear
9) 07020 Seal
10) 07022 Rolled Pin (Use 35 These parts are all available from Abingdon Spares LLC in the USA as standard T-Type parts (Abingdon Spares part numbers). Additionally you would need the gaskets (available from the typical Twin Cam supply sources) and the ball bearings which are available from local bearing suppliers.

At 08:18 PM 4/3/05 +0000, Steve Clarke wrote:
"Jim Alcorn does a rebuild exchange thing with water pumps. His rebuilt units are very nicely done but it is not inexpensive. I just put one of his on my car and it looks wonderful. They have redesigned the shaft such that it is tapered and a press fit into the pulley. According to Jim, the pump is superior to the original design and, given the pieces I have gotten from him, I don't doubt what he says at all. Give him a jingle."

At 07:07 AM 4/4/05 +1000, Robin Godfrey wrote:
"Apropos water pumps. I have just rebuilt mine because of noisy bearings. The replacement seal I bought from Moss was all metal instead of the rubber bellows type that it replaced. The new one obviously has to have an O ring to seal it which was not included.

"A friend had some stainless shafts made which he reports to be successful, however, watch out for the clearance between the impeller and body when the pulley is tightened onto the shaft! Peter Wood's tel No is 44 1296 730310"

On 7/18/2022, Dirk Van Ussel wrote:
Bearing sizes are: 37x12x12 (mm). For the purists it is R&M 4MJ12, for normal ones: 6301. I use shielded 6301.2ZR. Be sure to have a good carbon seal and surface it runs on.