Lotus 2004 Eleven Service Notes page 289

Lotus Service Notes
level of coolant will rise as the engine warms up and the coolant expands, and will fall again as it cools down.
WARNING: Do NOT remove the cap or bleed plug from the engine cooling header tank when the
engine is warm, as serious scalding could result from boiling water and/or steam.
When fully cold, the level of coolant should be up to the 'cold' mark moulded on the header tank. If
overfilled, the excess coolant will be ejected when the engine is warm, and if the level is allowed to fall too low,
overheating may result. If necessary, top up the system using an approved coolant mixture (see below) to
maintain full protection from freezing damage and corrosion.
Anti-Freeze/Corrosion Inhibitor
It is necessary that the coolant contains an anti-freeze with corrosion inhibitor to protect the engine and
heat exchangers from both frost damage, and corrosion of the metallic elements. In order to protect against
these dangers as well as raising the boiling point of the coolant, the Elise is factory filled with a 50% concentra-
tion of Havoline XLC, which is a mono-ethylene glycol coolant using organic acid technology (OAT) to provide
increased corrosion protection compared with conventional coolant additives. A yellow label around the header
tank neck identifies the coolant type used. The corrosion inhibiting carboxylic acids in the OAT coolant tend to
remain in solution rather than being deposited on the internal surfaces of the cooling system, thus improving
heat transfer and extending service life. Havoline XLC is the only recommended coolant product, and at 50%
concentration provides freezing protection down to approximately - 40°C. Even in warm climates it is recom-
mended that the concentration is not allowed to fall below 25%, in order to maintain full corrosion protection.
The simplest means of checking the antifreeze concentration is to measure the specific gravity (density)
of the coolant at a known temperature, using a hydrometer. The following table provides a general guide:
Concentration
25%
33%
50%
The coolant density reflects the effective level of mono-ethylene glycol, and not the level of corrosion
inhibitors present, whose effectiveness diminishes over a period of time. The coolant should therefore be
renewed every 4 years to ensure optimum corrosion protection.
In areas where the tap water is extremely hard (exceeding 250 parts per million), use of this water will
lead to 'furring up' of the system over a period of time. In such areas, distilled, de-ionised or filtered rain water
should be used.
Radiator Fin Cleaning
At service intervals, the matrix of the engine cooling radiator should be checked for clogging by insects,
leaves and other debris. If necessary, use a water jet from both above and below to clean the fins, taking care
not to damage the fragile tubes or distort the finning. At the same time, check the integrity of all cooling system
joints, and the condition of all flexible hoses. In snowy conditions, ensure the radiator air exit is cleared of snow
before driving the car.
KH.3 - DRAIN/REFILL PROCEDURE
To drain the engine cooling system:
1. Remove the undertray from beneath the nose of the car.
2. Disconnect the radiator feed and return hoses from the front ends of the thro' chassis pipes, and collect
the draining coolant. Remove the header tank cap to speed the operation.
3. Open the drain tap at the right hand rear of the cylinder block.
Note that draining of the heater matrix is not easily possible with the unit 'in situ', and that if draining for
the purpose of coolant change, this volume should be disregarded.
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Density @
20°C 60°C
1.039 1.020
1.057 1.034
1.080 1.057
Section KH