"Do you have any suggestions on improving the cooling systems of a Plus 8?"

D. Simpson

SUPPLEMENT: Would you have any supplemental suggestions for  4/4 and Plus 4 cooling as well?  Lorne

Bill Fink

The best solution for cooling a Plus 8 is an aluminum radiator - aside from that, there are improved cooling fans available which will greatly increase the air flow through the radiator which is much wiser than placing an extra fan in the front of the rad, which will tend to block air flow.

The standard radiators for the 4/4 and Plus 4 should be able to cope with most American conditions if the cars are set up so that all air flowing through the grille opening is ducted through the radiator and not allowed to escape below or to the side.

On the other hand, since most of the 4/4's and Plus 4's are at least 30 years old in this country, a replacement aluminum radiator would probably be a good long term solution. I don't recall 4/4's having cooling problems provided the stock system is working properly.


Melvyn Rutter

Ensure the front grill isn't "masked" by Morgan club badges on a badge bar, thus restricting air flow. You can turn the badge bar upside down, thus lowering the badges considerably.

Install a USA spec front cowl box with scoop.

Install an oil cooler kit with thermostat.

Install a high capacity radiator. We have produced one which is approximately four inches longer, with the height gain being in the bottom tank. The core had extra tubes, thus giving extra water capacity and cooling.

Install an electrical fan override switch, which can be operated early, so that when one comes up to a traffic jam, flicking it on will help to keep the temperature down at the earlist stage of a heating situation.



John Sheally II

Dear D.Simpson,

To keep your Plus-8 or any other model Morgan cool,

1. Invest in a aluminium RON DAVIS RACING or GRIFFIN Radiator and get it over with.

2. Use 50% Antifreeze 50% water.

3. The factory offers a metal duct that bolts below your rad (the grill or stoneguard bolts to it). This device ducts air on to the bottom tank where the cooling air should go to kool existing radiators.

4. NEVER install your electric fan in front of the rad, only behind it.

5. Have no running lights and or badge bar or badges in front of the radiator (pretty but hurts cooling).

All these things help but the aluminium radiator solves the problem/UP FRONT!!!!!Stay KOOOOOOL

Sincerely, John H. Sheally II

Gerry Willburn

Hi Lorne,

I would say that the largest single improvement that can be made with the  older cars is the addition of an overflow bottle/catch tank!  The design of  the radiator has built-in positive feedback for water loss.

It is impossible to get the top tank entirely full through the radiator cap.  There is an air bubble in the top of the tank above the filler cap level.  As the water warms up and the air expands, water (and some air) is forced out through the overflow.  As the engine cools, air is drawn into the radiator, increasing the size of the air bubble, etc..

With the catch tank installed, coolant is sucked back into the engine as it  cools.  As some of the air is also expelled during running, after several  cycles the bubble at the top of the radiator is replaced by coolant (until  the radiator cap is removed again).

In the SNOBMOG, we installed a radiator core with another row of pipes and a  catch bottle.  We have driven the car in 110 degree weather with no heating  problems, and the only time we remove the radiator cap off is when we drain  the coolant every couple of years!

One other thing on the older cars with the electrical temperature gauge.  The gauge is notoriously inaccurate. The sender is a temperature sensitive resistor (higher resistance = hotter) and lots things affect the resistance  (corrosion in the fitting, grounding of the radiator, etc.) so that the gauge wants to read hot when the car is not.  We "calibrated" the system in the SNOBMOG by letting the engine warm up at idle (it would read on the hot  side of "normal").  We assumed that this temperature was "normal" and found
the right size resistor to put in parallel with the sender so that the gauge  read normal!  Works great now.   When we crossed the dessert in 110 degree  heat it read just below the "hot" box on the gauge.

Our 1974 Plus 8, on the other hand runs a bit warm. We have not had it long enough to really attack the problem as yet.  I saw some references to the air exiting under the car. This is true. The best mod I have heard of  (which we have not done to our Plus 8 yet) is to install the poor man's air dam by hanging a piece of floor mat rubber under the radiator to force the air that flows under the radiator to exit under the car (rather than trying to blow up into the engine compartment).  This creates an extractor effect and sucks the air from the engine compartment (as well as air through the  radiator).  Couple that with a little foam padding between the radiator and  cowl to insure that the air flowing through the grill flows through the  radiator and most problems should be solved (assuming that the radiator is good in the first place).


John Worrall

The first thing to check is that the GAUGE is actually reading correctly! Sometimes they read high or erratically due to poor earthing etc, or a  faulty "sender". If it is reading correctly then

Check the "Otter switch" operation to ensure the fan is turning on correctly.

Check the radiator for condition and reverse flush it to remove any deposits.

A larger and more powerful fan is often a good answer.

A cowl box with air scoop can be useful in hot climates.

With aluminum engines check that a corrosion inhibitor or good antifreeze is  kept in the system continually to avoid silting up of the water passages. All of this applies to ALL models !

Hope this helps

With best wishes,  John Worrall


A sidebar to the Rover V8 history is still germane today. General Motors sold the Buick 215/Oldsmobile F-85 to Rover because they thought they had a head gasket problem with the engine. In fact,  it was the reaction of standard anti-freeze and the engine alloy which gave off a deposit that clogged the head ports and blew the gaskets. Rover V8 head gaskets also had a poor reputation until the probem was fully understood.

For this reason, it is strongly advisable to use aluminium friendly coolants like Texaco Anti-freeze. They did a lot of work to come up with a safe formula. Also, Rover now has an in-house "Summer Coolant" mixed specifically for the Rover V-8 block.