Torque Shop

After a few days of lethargic performance from my car, I sent it to the workshop, which asked me to leave the car there while the mechanics diagnose the problem.

Two days later, the workshop called me with a list of items that needed replacing, together with the cost of the parts and labour.

Of the parts to be replaced, the most costly item was camshafts.

My car is only 51/2 years old and it has been serviced regularly and fastidiously.

Is it true that engine camshafts can get worn out and need to be replaced at some point?

The camshafts in the engine open the inlet valves in a precise sequence to allow air and fuel into the cylinders, then close the same valves and subsequently open the appropriate exhaust valves to release the burnt gases.

Every action by the camshafts is perfectly timed. Therefore, a worn camshaft (or two) will cause a change in the valve-timing, which would lead to a deterioration in performance.

However, camshafts rarely wear out and definitely not in a car that is barely six years old and has been serviced regularly.

As a matter of fact, even with cars which have done more than 200,000km and have engines that need to be rebuilt, the camshafts are among the engine parts that seldom require replacement.

If, indeed, the workshop's diagnosis shows that a fault exists in the valve-timing, this is most likely due to a worn timing belt (or timing chain as used in many cars). This belt connects the crankshaft to the camshafts and keeps the latter in perfect timing.

Another likely cause of the fault is a defective belt or chain tensioner, which will result in erratic valve-timing.

Make sure the diagnosis includes a visual inspection of the camshafts and insist that the workshop shows you the wear in question before you allow any work to proceed.

Better still, get a second opinion.

Shreejit Changaroth

A version of this article appeared in the print edition of The Straits Times on June 24, 2017, with the headline 'Torque Shop'. Print Edition | Subscribe