For a bit of additional cooling as an auxilary radiator which is better, an in cabin heater say from a clubbie/moke or a under bonnet fresh air heater.? Obviously the under bonnet one has the advantage of not cooking you during summer.

Underbonnet one wins hands down, it's permanently connected and has no tap to clog up as Clubby ones always do.
Also it gets great airflow while moving, without cooking you in summer.

If you want the cooling but don't have room under the bonnet for the heater box, just hook a bare heater core behind the grille.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks, I have what I think is a Moke heater in at the moment and it does make a difference on the hotter days as long as you have the fan on which can make it a bit uncomfortable. I was thinking of putting an under bonnet one in in its place but didn't know if it was be less effective.I figured the airflow would help when moving but not sure how it would go when you get stuck in traffic.Does it have a bigger core ?

Drekkus

A mini only just has enough cooling capacity and you find that over the years the radiator fills up with crap. That leaves you with less circulating volume in the radiator. Also you may find your water pump have the vanes fairly corroded.

The only way to fix overheating problems is the have the radiator out and have a specialist take the takes off it and rod out the crap. New high capacity water pumps are dirt cheap from any of the mini specialists.

You could also fit a radiator out of a late model moke or from a morris 1100. A few things to change around but it also gives you a greater coolant flow.

Then your car should run cool under all but the hardest of driving.

I have auxillary heater cores strapped behind the grill on two of the cars here. It does help when everything else is right but you must remember two things.

The heater core is fed by fairly small diameter rubber tubing so therefore the circulation rate is lower and the coolant spends more time in the heater core. Great for heating a car when it has a fan behind it. Not so great for cooling the coolant.

The second thing is the heater core is designed to give off heat where as a radiator is designed to cool the coolant. There is a significant difference.

So, an auxillary "radiator" will help cool a hard driven car but it will not fix a basic overheating problem.

Oh

One last thing - you can have both a in-car heater and a behind grill auxillary radiator. Just a bit of fancy plumbing and some under bonnet taps to control the flow.

Like this and it works well-just make sure you rubber mount it

_________________
_______________________________________________________________________________

The pump is a high capacity one and looks ok, the radiator is a reco one but perhaps it has got a bit of crap in it , who knows.Its really only been on the hot days we have had lately that it has tend to get a bit warmer than I feel comfortable with, today its no problem.
I'm just looking for a little bit extra and if the fresh air one is going to be better than the in cabin one I already have then I'll go with that.I have considered plumbing both in but would that be a bit of overkill?.

No - having both is not a bit of overkill. But you need taps to be able to turn the heat on and off and to direct the flow. There are plenty of aftermarket taps around.

The reason is that is mid summer you dont need the cabin heater blowing hot air all over you so you need to be able to turn the heater off and divert the flow to the auxillary (as Doc says - the standard taps fill up with crud and dont work).

Then along comes winter and you want the heater and you dont want the extra auxillary radiator stopping the car getting up operating temperature so you turn off the water flow to the auxillary.

To have both is only some T-pieces and some aftermarket water taps (or more expensive gas taps).

Mike

I had thought if I did plumb both in that I would just block the air intake on the fresh air heater in winter but would that be enough to allow it to get up to operating temperature.
Ideally I'd like to just have the one heater but I guess it wouldn't be too hard to experiment with one or the other or both.