MGB V8 - Cooling














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It is clear from reading from all sorts of sources that the engine cooling on the MGB with a V8 is somewhat marginal. However it appears that the principle problems arise in slow moving hot ambient situations. This clearly suggests that the issue is linked to either the radiator fan arrangement which is rather agricultural, or the ability of the water pump to move enough water around at idle.

Many people seem to try to overcome the problem by installing a manual switch for the fans, but I fundamentally believe that this will not make a significant difference unless the existing fan switch is just set too high. Another option used is an aluminium radiator, but again the evidence shows that it is not the ultimate ability of the system to remove heat as this would manifest itself as overheating at spedd when using full power - for example when climbing a long steep hill or of course track work.

So my chosen option to overcome this problem is as follows:

  • Standard MGB V8 radiator

  • Kenlowe "sucker" fan on the inside of the radiator

  • Dual switching of

  • Temperature controlled electric water pump

Having spent some time thinking this through I believe that this will give me a solution that will deal with the overheat at idle situation. The big advantage of an electric water pump in this respect is that it can run at max speed at idle whereas obviously an engine driven mechanical one can't! This will significantly increase the heat taken from the engine at idle - but clearly that has to be linked to the ability to get rid of that same heat through the radiator. Assuming that I stick to the standard V8 radiator the only way I can improve the heat loss is to increase the air flow across the radiator. Referring to the Kenlowe website suggests that ideally I would need the 16" fan, but the radiator is only 14" tall! So the chosen fan is the 13" Heavy Duty version. It should be noted however that this fan draws 25 amps! and will hence need some changes to the electrical supply of the vehicle! See electrics.

You will notice that the collar that comes with the sucker fan is 75mm deep. This also presents a problem on a BV8.


This is where the electric water pump gives another advantage. Given that I no longer need the impellor of the mechanical water pump, I can also cut the nose off the pump and gain the extra space I need. In terms of the anti-roll bar the middle picture above shows that I have just enough room (320mm) to mount the fan above the roll bar. I also hope to make a more professional looking bracket for the fan and weld it to the radiator, rather than use the clips supplied that you push through the fins.

Finally the water pump. The one I have is a Davies Craig EWP80 item. I also have the electronic controller and the booster pump. My intention is to set the main pump in the bottom hose between the radiator and existing pump. I will remove the impellor from the mechanical pump and cut off the nose to give me additional room between the engine and radiator. The electronic controller will be mounted under the dash with a temperature probe inserted through the thermostat housing. There will be no conventional thermostat. In addition I will fit the small booster pump in the heating circuit. This will achieve two things, firstly to ensure that heat is always available to the passenger saloon even if the main pump is not running. It will ensure water movement within the engine to prevent hot-spots that might occur is there was no water flow at low temperatures.