IT is almost a given that when a customer rolls in (or tows in) their car, he will describe the problem with a veritable cacophony of sounds. Sometimes this will shed light on the problem but mostly it serves to confuse your long suffering foreman even more. To be able to correctly diagnose the problem, here are some common sounds your car makes to make it easier to describe to your foreman especially if the car is a non-runner.
Firstly, it is essential that you know how your car sounds like when it is working correctly.
The engine hums, the tyres will thrum and the windows whistle (mine does, anyway). An early morning start will reveal the engine fans whining and the engine ticking quietly to itself. The exhaust will roar when you step on the loud pedal and the doors make a solid thump when you close them.
Your tyres will make a certain thrum or a quiet whizz depending on the type and size of tyre. A Land Rover or 4x4 will have a roaring sound which heightens with speed. Of course, a loud bang will indicate a blowout but you will definitely know this since you would also be busy trying to control the car. A more common sound is a rhythmic thumping that increases in frequency the faster you go. This is usually a flat spot on one or more of your tyres. This is usually caused by locking up the wheels during a skid. It is not serious, just annoying.
However, check if you have not picked up a ‚pimple‘ on the tyre. This is more serious and requires immediate attention as the tyre cords have failed.
A rhythmic blowing sound under the bonnet of your car which picks up frequency when you rev it is an indication that one or more of your exhaust gaskets have ‚blown‘. Sometimes it also manifests as a (excuse my French) farting sound. This will not fix itself as the hot exhaust gasses will only make it worse with time. Get the gasket replaced.
A ticking from under your bonnet which increases in frequency when you rev the engine is sometimes the tappets. This is usually easier to hear when you put your ear closer to the top of your engine. This is usually not serious unless it is loud. Then this means a valve adjustment is necessary. Have your mechanic listen to the engine.
A ticking noise from under the car which increases when the speed goes up is usually a universal joint running out of grease. This only applies to rear wheel drive cars. Get this sound fixed immediately. The joint might fail and leave you stranded.
On front wheel drive cars, a constant clacking noise as you turn the front wheels is due to the constant velocity (CV) joints wearing out. In a straightline the noise disappears. It will also get louder and louder as you ignore it, until the joint finally gives out. This is usually in the middle of a busy highway, in the fast lane. Save the embarrassment and get those CV joints replaced.
If the screech is loud and usually occurs from a slow speed and disappears when the engine revs higher, one of your belts is loose. Some cars have up to three belts, so a three-piece screech outfit under the bonnet is highly irritating. It is louder from outside the car so those „evil eyes“ from pedestrians is highly warranted. This is an easy fix, so please get your mechanic to properly tighten or replace the belt(s).
If this sound is only apparent in the mornings from the front of the car and disappears as you drive, it is only the rust on your front discs. Some cars have cast iron disc brakes and only need light rain or dew to start rusting overnight. Not a problem as the brake pads will scrape off the rust at the first or second application of the brakes. A scraping sound as you make that tight turn in the parking lot is something else. Leave a note on the poor guys‘ car or ignore if it was the parking lot wall.
If there is a hissing sound under the bonnet at idle, it is not a snake. It‘s an indication of an air leak. You won‘t hear it while driving as it may be quite faint. Check all rubber and plastic vacuum lines for perishing or breaks. Replace if necessary. Just in case, pop the bonnet with care, you never know if it was a snake after all.
On automatic cars or 4x4s with rear wheel drive, a fairly distinct clang or clunk will be heard from under the middle of the vehicle as you move off. This is the spline in the driveshaft binding as you slow down or start off. Not a big problem, but you can reduce it by having the spline re-greased every 6 months or so.
Clunking or Clacking
If you hear this sound, it will usually come from either side of the front wheels when you hit a bump or at slow speeds. This is your ball joint telling you that it is ready for the afterlife.
Get it fixed as it may fail completely.
Not what you think. This is usually apparent when twirling the steering wheel in tight spaces. It is the pressure relief valve in your power steering pump. Not serious but you might want to check the fluid level or the system itself for leaks. The sound will be louder as the fluid deteriorates or runs low.
No. Not from your better half. Usually the grumbling come from any of the four corners of your car. It is the wheel bearings and they need replacement pronto.
If the grumble comes from under your bonnet, then it is the water pump bearing which will also manifest in a leak or smell of coolant.
The sound is also the last thing we foremen hear when you leave the workshop. See you at the next service.