The Triumph Dolomite Club - Discussion Forum

Does anyone have any advice about whether to fit a 6-vane or a 12-vane water pump to a 1976 Sprint. The engine tends to run a bit hot when idling, although there is an electric fan fitted, which helps a bit. The existing pump is 12-vane, but, since I'm replacing it anyway, I'd rather fit the more effectice option. Thanks.

If you change the number of pump vanes, you also need to change the cover to match.

To be frank, you'd not notice the difference between the two if each are in good order. A repair kit is all that is often required, rather than a new pump.

Running hot could be caused by many things; air lock, ignition timing, poor radiator, binding brakes, badly adjusted electric fan ...

I've moved the thread here because it is defintely "Dolomite-related".

I think it is logical to have 6 vanes because each vane takes up the space that could have been taken by water. I suggest that the 12 vane was an idea by some to lessen the load on the jackshaft rather than pump water better.
Also to pass MOT you have to have the carbs set rather lean which means hotter burn with modern fuel.
My MOT man would say "you're only going to change it when you leave aren't you?" and I would smile.

You can also ask for the test to be taken at 2000 rpm rather than idle, which often sees a pass where idle gives a fail, but for many cars it is a visible test only due to age.

How about fitting one of those fancy Saab pumps with the the 6 curved vanes, IIRC they go under a 12 vane cover.

But I agree with everyone else, there are a multitude of reasons for hot running, it's not necessarily the pump which is at fault here.

Steve