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 FAQ #46
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1.6 Petrol engine noisy tappets when cold?
There are 2 known issues on this.

1 simply comes down to changing the grade of the engine oil. The engine has 'hydraulic' valve tappets and relies on the oil pressure building quickly to take up any slack. If it's cold and the oil is thick then it takes longer. A lighter grade of oil should resolve the issue

The second is caused by the 'charcoal canister electrovalve'

Fuel tanks nowadays are sealed and not allowed to vent to the atmosphere as hydrocarbons being bad for the atmosphere etc.

So how do they allow the tank to vent and get rid of the hydrocarbons (vapour)?

They fit a charcoal canister under the wing and a pipe runs from the fuel tank to the canister.

The canister then has a pipe that connects to the inlet manifold.

At a predetermined time the canister valve will open and close and the speed of its opening and closing is determined by many factors.

When it opens it vents the hydrocarbons into the inlet manifold where they can be burnt

The clickng noise you hear is the valve opening and closing and it sounds like a single tappet is loose."
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FAQ Posted by Dave_Retired.
Info Created: 01 June 2007
Last Updated: 01 June 2007