From the old forum, some might know I had planned to plumb up the cooling system like this, with the heater taken from the pipes in the tunnel, almost at the heater position:-


But at idle the flow seems to be a bit lacking.
So the new idea is this, using a switched booster pump on the heater circuit:-


My question is this, will this increase the flow from the engine, when needed with the booster pump,
or will the water take the easy path of flowing round just the radiator/heater matrix ?

I would suspect that the two pumps would interact with each other. So if the main pump is going slow, then the auxiliary pump wouldn't be able to move much more through.

Have you either considered getting an electric pump that you could use for the main pump? So if one was fitted, then you could run the pump at the speed required to keep the engine cool, but also it can run after the engine has been switched off, to stop the problems with heat soak.

If you want to use just an auxiliary pump, would it be possible to pipe it up as two separate systems? It could be then used as previously said as a way to cool the engine, after it has been turned off.

I think that the auxiliary pump turned on when the main pump is running, will just cause the ratio of the amount of water passing through the heater matrix and radiator.

You can get the electric pump from Evil bay, for not a massive amount of money.

I have always found it to be better all round to blank off both the small bypass hose connectors and also the heater outlet on the cylinder head. You then use the Allegro type double thermostat housing with a feed to the heater built in. The heater return feeds into the bottom hose by the water pump so that the heater becomes the bypass circuit and hot water flows round it all the time. I have used this set up on all my Mini based kits.

On the Coupe I am also using a Davies Craig electric water pump in the bottom hose. It is switched on by a thermostatic switch after the main thermostat opens. It moves a lot of water round the heater and radiator systems so flow rate is not an issue

It's not the best idea to block of the heater take off, as No.4 cyl (already furthest from the water pump / rad) tends to run a little hotter, having a take off from here allows better circulation and cooling.

As for the bypass hose, if you have it, keep it - it really does work at getting the engine up to temp efficently!

Just my experience of being around Minis since I could walk (And my Dad's thoughts having been around them, since they began)

Hi Jamie

You ever get that Coupe off the pallett started ?

This one??







Not yet, done a few Minis, and currently working on my GRP shelled Mini, aswell as having just bought a Lotus Elise

A Mini Minus ?

S1 or S2 Elise ?