My engine start did and didn’t go exactly to plan. The process was spot on, but I needed to make a judgment to proceed. The process I followed was:

  • Charge / top up battery
  • Connect the battery
  • Fill coolant
  • Fill oil
  • Set throttle idle position
  • Fill fuel
  • Check for oil pressure
  • Start the engine
CTEK charger

It’s worth planning ahead and get the battery topped up before you attempt an engine start. If you don’t have a battery isolator switch and you leave the battery connected, a Caterham will start having engine starting problems after not having been run for a few weeks. Besides, deep-discharging car lead-acid batteries shortens their life.
Therefore a conditioner is a wise investment. I use a CTEK MXS5.0, which can be connected through the 12v socket with the current wiring configuration. However, since I haven’t connected the socket yet, the connection is made directly to the battery.

Simple multimeter test (resistance)

Before connecting the battery I feel it’s worth doing a simple electrical test with a multimeter, just to make sure the loom doesn’t have any obvious short circuits. With the isolator switch on, there should be significant resistance, and therefore a low current, i.e. not likely to blow fuses and cause fires.
The maths is:
Electric Potential (Volt) divided by Resistance (Ohm) = Current (Ampère)
12 Volts / 14,690 Ohm = 0.00081 Ampère
So, the current was only 0.0008A, and that’s low enough.

When you connect the battery, make sure you always connect the positive (+ve) first, before the negative (-ve), and when you disconnect the battery always disconnect the -ve first.

Careful to pickup De-ionised Water not AdBlue 🙂

Coolant was supplied in the kit, but it was concentrate which needs to be diluted, so a quick trip to the local motor factors to purchase some de-ionised water. 5 litres of concentrate were supplied, with a recommended mix of two parts water to one part coolant for -20C. I therefore bought two 5l bottles of de-ionised water and made up enough 1:2 diluted coolant.

Before you fill the coolant, make sure the drain plug on the radiator is tight, and the bleed plug is loose. Fill through the expansion tank, litre by litre. Take your time with this, as it burps out the air in the system. I am sure there is a better way, but I tend to try and force the air through the system with the occasional blow into the expansion tank. Just be careful doing it this way – this stuff is harmful.

Min is the cold mark and Max when hot; it’s called an expansion tank for a reason
Note: I lost a little coolant due to leaks.

My system eventually took a little over 6 litres of coolant.

Dry sump tank dipstick

Oil filling is a simpler affair, and the engine oil was supplied with kit. The current spec 420R kit has a dipstick built into the dry sump tank lid. I put 4 litres into the dry sump tank, and another 3 litres into the top of the engine.

I am fortunate enough to own an Easymap lead, so I can connect a laptop to ECU to see what the current throttle position sensor reading is. There isn’t much adjustment in the throttle position sensor itself. Most of the adjustment is done using the throttle stop. I adjusted the throttle stop so the ECU sits at “Trottle Site” 0.0 at idle position.

Now its time for fuel. You need to add a sufficient amount of petrol, but the problem is that I don’t know how much is sufficient. However, why skimping here, when the tank has to be full for the IVA test? I filled up with two fills from my 10 litre jerry can, so approx. 20 litres of fuel.

Inertia switch

To build oil pressure, I just disconnect the inertia switch, which disconnects the fuel pump. I have seen builders removing the spark plugs to reduce the compression, but I have a freshly charged battery which is more than capable of spinning the engine over even with plugs at a speed sufficient to generate oil pressure.

However, we never saw any oil pressure on the oil pressure gauge!

This was a serious spanner in the work, but I have read about builders who have had this problem, resulting in various parts being replaced. Sensors and gauges have been known to be faulty, but I had to make the decision on whether to proceed with no oil pressure reading.

The oil was not leaking from anywhere, but what convinced me that it was ok to proceed with the start was I saw oil was returning to the top of the dry sump tank. So the absence of oil pressure was just an electrical problem with the sensor or guage with I could solve later.

The inertia switch was reconnected. Ready to go.

Before you try for that initial start, there is one more thing to do, prime the fuel system. The fuel pump runs for a few seconds each time the ignition is switched on, but then it doesn’t run again until the engine is actually running. Having just a few seconds of an active fuel pump just isn’t enough for a bone dry system. So switch the ignition on and off a few times, until you hear the point when the pump starts reaching the regulator pressure and the tone changes.

Finally, I pressed the starter button!

My engine spluttered on the first spin, and started on the second.