Auto Mechanics Paper 2,Nov/Dec 2011.  
Questions:   1 2 3 4 5   Main
General Comments

Question 4

The sketch below shows a poppet valve.

(a)        Identify the parts labelled U, V, W, X and Y.

(b)        State the reasons why some diesel engine inlet valves are masked.

(c)        State three effects of incorrect valve stem clearance.

(d)        State the function of the poppet valve.


Most of the candidate could not provide the required responses to part (a) and (b) of the question.  The required responses to parts (a) and (b) of the question are:

            (a)        U – Head.
                        V – Neck.
                        W – Stem.
                        X – Tip.
                        Y – Face.
(b)        The reasons for masking the inlet valve of some diesel engines is to help reduce swirl in the cylinder of the compression ignition engine.

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