This is not the most elegant method but it's virtues are simplicity, no soldering, easily removable and no altering of the existing system. Frankly, I tried it as a temporary test and never got around to seeing a pressing need to change it. Please forgive me for being too detailed here but, for some, it will be a first Morgan modification.

The principles are easy to understand...the wire delivering power to the rad fan goes through a heat sensitive switch. This switch turns the fan on and off by allowing the current through (or not) at preset temperatures. The advantage with a bypass switch is that it allows you to turn on the fan BEFORE the engine gets hot and yet leaves the original installation in place in case you forget.

To do this you must create a second pathway for the power around the rad switch and then on to the rad fan. This new path run through a switch YOU control and near at hand when you are driving.

First disconnect the battery.

Now you need a few bits to add to what is already there. Two splitter (?) fittings (one female into two male), two female connectors, one simple on-off switch, 2 wood screws and 10 feet of two strand wiring. The rad switch is found on my car at the bottom of the radiator. They have two prongs or male connectors for the power going in (with a plastic covered female connector) and the same for the power going out. I simply removed the connectors, slipped on a splitter on each of the switch's prongs and reconnected the rad fan's wires to one (each) of the sets of splitter prongs. So now I am back as I was originally with a normally functioning fan with the exception that I have an extra connection available in and out at the rad switch.

I then used the electrical wire in the appropriate thickness (tell the fellow at the auto store where you buy this stuff that you hooking up a rad fan...) I ran it from the rad fan switch up to and then along with the other wires on the outside of the inner wing, then pushed through the rubber grommet through on the firewall near the driver and into the car.

Here you have options on what and where you wish to have your switch. Though you could use one of the unused switches on your I would suggest you leave them alone unless you are electrically inclined..I also have doubts that an unused rear fog lamp switch can happily take the power of a big rad fan. I bought a small chrome push-pull switch, made a small L-shaped bracket with three holes on one side (to wood screw it into the wooden member under the dash and to the side of the car) and then made a hole in the other side of the my L-bracket to put through the pull switch and tighten it. In this place it is easy to reach, easy to wire and still out of the way and hidden. Wire each of the ends to one of the wire terminals on the switch .

Now go back to the radiator, attach two female connectors to the wires (easy to do) and plug them in to the extra male connectors you put in. Reconnect the battery. (If you left the new switch on the fan should come on as you are connecting the battery...turn it off).

Test the switch. Now turn the switch off and let the car heat until the rad fan comes on by itself. If it does you are fine. Turn everything off and affix the wires where convenient with electrical tape so it is out of the way but not stretched.

When you turn it on, you must look casually at your passenger and explain that you are "activating the Turbocharger".

OTTER SWITCH(aka the Morgan radiator fan switch)
by Lorne Goldman

It has been those who know him that Maurice Owen used travel in the prototype Plus 8 with a bottle of coolant behind the passenger's seat. He was uncomfortable with the "plug in" rubber and spring held Otter rad fan switch used by the Company and wanted some extra protection just case.

True or not, I am now aware of a number of incidents where this switch has,  in fact, badly leaked or "popped" out leading to an instant draining of all coolant in the engine. I know of no aftermaket rad makers who will drill holes in their product to provide for the Otter rad fan switch. They simply do not trust it and neither do I.

The wise move is to have a local machinest weld or solder in a threaded hole for a threaded switch. There are threaded options from the manufacturers of each Morgan engine but most of these are made to placed in the hottest part of the coolant system at the top of the rad of engine. Most Morgans have the switch installed at the bottom of the rad, with doubtful wisdom, where the coolant is at its coolest.

Placing a top mounted switch at the bottom of the rad will have the rad fan come on later than it should. There are two options, find a switch with an appropriate lower range (or a choice of ranges with the same thread)  or move the switch to the top of your rad.

You also want a tright range between on and off..especially with the EFI cars which are made to run hotter. A too-woide range will have you rad fan running on for 5-10 minutes after you stop the car!

After trying many, I have found that 1980-1990 BMW switches fit the necessary critertia and also require one of the smaller standard rad fan switch thread fittings of 15mm. Here are the available "on temps" and part numbers. The range is about 5C.

61311364272/82  = 82C  (179F) switch (gold body and white top)

61311364272/86  = 86C (186F) switch (gold body and white top)

61311364272     = 91C (196F) switch (gold body and white top)

61311364273     = 99C (210F) switch (gold body and red top)

I had my rad made with two fittings to experiment. (EFI Plus 8). I find I am most happy with the 91C at the bottom of the rad. For those looking for an even earlier "on" temp simply choose one tf the lower temp swtiches and have it placed at the top of the radiator.

PORTING YOUR HEADS

This process matches the exhaust ports of your engine heads to your exhaust manifolds.