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Last year my MGB never stayed cool. She was quite the hot ride, literally. Her temperature would go from the middle of the temperature gauge to the red high level in a heartbeat once idling. Last fall I started to address this issue.

As we all know, keeping her cool requires five things:

  1. A functioning radiator,
  2. Properly mixed antifreeze,
  3. Free flow of antifreeze throughout the engine and cooling system (no blockage or dirt).
  4. Functioning and correct thermostat,
  5. Proper hoses that are not worn or leaking, and
  6. A functioning fan.

Last fall I started by addressing numbers one to four. I took my car to a specialized radiator shop to have it flushed, proper antifreeze put in and a winter thermostat (190 Degrees) installed for driving late fall. The results were night and day. First, there had been no thermostat in the car and second, the liquid in the system was nothing but a foamy dish soap type fluid which the garage had never seen before. The garage confirmed that the radiator was fine, the engine was properly flushed, and the winter thermostat and 30% antifreeze mix was installed correctly. They did mention however that the fan was a low-speed fan, and since I had a fan switch that I should keep it on all the time.

I was not crazy about the fan and the switch in the first place. The fan was mounted by nails through the radiator. Last Fall, I decided to ordera new Revotec Fan and Revotec Switch. This year I installed it. First, out of the box, the aluminum brackets to support the fan onto the original radiator bolts was cut perfectly but the finish had much to be desired. Therefore, the first thing I did was to sand the surface a bit and apply one quick coat of Dupli-Color Self Etching Primer and then one hour later, two coats of Dupli-Color High Build Fleet Coating. I really like using these products because the primer is ready in an hour, and the paint can be second-coated after ten minutes and is dry to touch in one hour. The finish is durable, and it coats beautifully.

After it was painted, I moved on to the physical installation. This task was divided into two parts: one, remove the old fan and install the Revotec fan using the painted brackets, and two, drain the radiator and install new hoses. The top radiator hose needed to be cut to accommodate the Revotec’s accurate and adjustable thermostat. We will discuss this later when we calibrate the fan temperature start-up.

The bracket installation was straightforward. A collection of nuts and bolts assembled in accordance with the instructions. But who reads instructions when it’s this simple? Not me until I had to because something just did not add up. So, just a note, follow the installation instructions step-by-step and the installation is a breeze and should take less than an hour.

Once installed I proceeded to drain the radiator into a large oil collection pan that I purchased just for radiator fluids.  I changed all the hoses, top and bottom and to the heater. They needed new hoses as one can see from the bulging hose here.

Before installing the top hose, I had to cut a ¾” section out of the straight part coming from the thermostat. This would allow the insertion of the Revotec thermostat in between the cut top hose as shown below.

Now that the hoses, thermostat, and fan were all connected, I could fill up the radiator again. Before putting the fluid back into the radiator, I used several layers of cheesecloth to filter out any particles and dirt from the antifreeze that was relatively new (last fall). I poured it into a Juice jug that was confiscated from our kitchen and is now in the garage.  The juice container has a nice spout and allows for easy pouring into my radiator and into the top of the thermostat.  I found the best way to fill it up was to use my old top hose to fill the radiator from the top.

Once the radiator was full, I re-attached the new top hose and proceeded to fill the top of the thermostat until it was full. I then ran the engine until it was hot (5-10 minutes) and refilled the top of the thermostat again. I poured the remaining antifreeze into the expansion tank. (As a note, the system worked and after driving a few days all the antifreeze was back in the system and the expansion tank was empty).

Now, the system was all ready for the wiring set-up. First, I ran the switch wires from the driver’s side behind the dash to the passenger side and came through to the engine compartment using the hole for the Heater cable. In doing so, I noticed the grommet was in poor shape, so I replaced it. In my case, I also had intended to install a new heater cable, so this timing was perfect since I had ordered and received the cable.

The wiring set-up is straightforward and only required me to cut one blue wire since my installation introduced the switch into the system, which is not really required.  But in for a penny, in for a pound. There was no science to the placement of the switch other than the fact that I had a torn piece of material at the bottom left side of my steering wheel, so now the switch covers it and holds it in place (a natural solution).

I then set-up to solder bullets to all the wires. I soldered a bullet onto each wire then used a heat wrap that had glue inside so that when heated, the glue oozes out the ends and seals perfectly against weather and water.

Once all the connections were made, I followed the Revotec instructions and used the green fan power wire from the radiator harness at the front corner of the car for power, and the grounds went to the far rear existing ground screw on the side of the engine compartment. As a note, I had also installed a black and red wire for future fog lights to the area where the fan power will be connected, with a fog light switch into my cockpit.  Therefore, I used a double connector for the fan’s bullet power line so next week my job to connectthe LED fog/driving lights. will be easy-peasy.

I had to calibrate the thermostat. In my case, it was almost perfectly set to where I wanted it to be as received from the factory. However, I had to perform the calibration as follows:

“The temperature at which the fan switches on is adjusted by turning the small control inside the body of the unit.  The control has a single sweep of just over 3/4 of a turn. The temperature range is 70°C to 120ºC increasing in a clockwise direction. Turn the adjuster with a small screwdriver.

Do not use excessive force as damage may occur.

Start by setting the unit to its minimum operating temperature (fully counter clockwise). Start the vehicle and get the engine warm. The fan should operate when the engine coolant temperature reaches about 70ºC. Increase the adjuster slowly until the fan stops running. This allows you to check the on/off function of the controller. Continue to increase the setting until the fan remains off when the engine is at normal running temperature. It will then switch the fan on when the engines exceeds normal operating temperature.

When you have finished with the adjustment and the fan control is operating at the desired temperature fit the dust cap onto the top of the unit.” – Taken from Revotec’s Instructions.

Once the calibration of the fan was adjusted perfectly and I confirmed that the switch works, it was time to go back and revisit the wiring situation. I spent the time to wrap all the wires with MG Blue Electrical tape and secure them with tie wraps.

This of course was just one of the many installations, repairs, and maintenance I have performed over the last month. Hopefully, she will keep her cool this summer, even on a hot day in traffic 😊