Warped brake disc likely cause

Q1: My Isuzu Citation sometimes produces a slight squeaking sound, but only briefly when I apply the brakes. The mechanic looked at the brake pads and found nothing wrong. What could be the problem?

You probably have a bent or warped brake disc or uneven brake disc surface.

The squeaking sound is coming likely from the brake pad indicator. Generally the brake pads are still considered good if they are more than 10 mm thick.

Check the brake component operation and clean where necessary to solve the problem.


Q2: My BMW 3 Series has clocked over210,000km.  Of late, the engine makes a screeching sound on cold-starting and the sound goes away after the car has been driven for a few minutes.

The noise appears to be coming from the drive belts or pulleys just behind the radiator. 

I suspect the bearing in the pulleys may need to be changed. To keep cost down, can the bearing just be changed instead of the whole pulley system and belts? 

Is it possible that the belts are just dry/dirty and need to be smoothen on its contact point with the pulley to stop the noise, which comes only once in a while?

It’s a long shot but is it advisable to “wax” the belts with a candle to smoothen them?

The probable cause of those unwanted sound is loose drive belt, faulty pulley bearing and/or even warped surface of the drive pulley.

We recommend changing the set to resolve the issue once and for all.

You are strongly discouraged from using any kind of wax or chemical to temporarily resolve the noise as this may worsen the problem. Substances such as what you have mentioned might stick and harden, and this could affect the proper operation of some other components.


Q3: I know someone in the United States who uses 100% radiator coolant instead of water to fill up his radiator. If this is a good idea over there, wouldn't it be even better for Malaysia, which is hot all year round? 

What is generally true about the radiator coolant is that it contains glycol-ethanol which fights rust.

It is also an anti-freeze agent to prevent the coolant from freezing and it has a higher boiling point.

If you use 100% coolant inside the radiator, it is too concentrated hence the metal’s lifespan will be shortened because it will react with it much more.

Bear in mind that we are living in the tropics. Anti-freeze is not required even though it is one of the chemicals inside the coolant.

Follow the manufacturer’s recommendation and you should be on safe ground.