I washed my car engine, and it wouldn’t start after that. It took a while before the staff at the carwash managed to get the car running again. My question is, should I wash my car engine at regular intervals, or should I avoid washing it altogether? Ask Selvaraj form Puchong to Mr Foreman

A: One thing all people who love cars have in common is washing them regularly. But, by washing our cars, are we doing our cars a service or can we damage the car’s internal bits and finish by going to the neighbourhood carwash?

One thing that I notice is that the prices keep going up and up. It used to be RM5 in the 1990s, now its RM7 or more. If you go to carwashes where you pay a monthly or membership fee, it works out to be much more. Of course, it is more convenient going to these places, but if you really love your car, take some time to detail it yourself.

Regular washing and detailing can boost your car’s resale value by thousands of ringgit down the road. But doing it right is not straightforward. You may be using the wrong chemicals or soap, and may even damage your car engine or paintjob if you don’t know what to look out for.

If the carwash you go to does not wrap certain parts in plastic to protect them, for example protecting the alternator and throttle body before spraying degreaser, stop them immediately.

They obviously do not know anything about washing car engines. Wrapping sensitive parts, especially exposed air filters, are part and parcel of washing car engines. Stop going there altogether and find a more knowledgeable carwash.

The components under the hood are not designed to withstand large amounts of water.

Using a high-pressure water jet can damage the engine by cooling it down too quickly, and can even cause metal to crack. The electrical system in modern cars are very resistant to moisture, but there is no telling what a high-pressure hose might do to it.

If you do want to wash your engine, you should consider telling the car wash attendant to use a regular hose instead of a high-pressure stream to clean under the hood. This way, you minimise risks.



Car Washing on Back Yard. Transportation Photo Collection.SYSTEM

The most important thing you can do to keep your car’s finish looking great is to wash it regularly.

Doing it at the automated carwash is about the worst thing you can do. Some of the brushes used by neighbourhood carwashes are poorly maintained and will introduce fine scratches, called swirl marks, into the car’s paint finish.

It is best to hand-wash it yourself. Just remember that loose dirt, sand, and other fine debris are the worst enemies of your car’s paint.

If you wipe across the car’s surface with a dirty sponge, you can easily cause the same type of fine scratches as a drive-through wash, or worse.

The best way to avoid it is to use two buckets of water: one with car-wash soap mixed in and the other to rinse out your sponge. Use the first to clean off the dirt and gunk. Then thoroughly rinse the sponge in the second bucket and dip it back in the first bucket to continue washing.

This will help keep dirt from getting into the soapy water.

Start from the top and work down. The lower regions of the vehicle are typically the dirtiest and are more likely to contaminate your sponge.

Avoid washing and waxing your car when the weather (and paint) is hot. A hot surface causes soap and wax to dry much faster, which will make the process harder and more time-consuming.

Choose a cloudy day, or park the car in the shade for an hour or so, or do your work in the early morning or late afternoon.

For waxing, it is best to work in small sections so the wax doesn’t dry out too much before you can buff it off.

Don’t use dishwashing liquid. Dish detergents and household cleaners will strip off the paint’s protective wax and introduce salt into the paint.

There’s a plethora of car-wash soaps in the stores. Look for a branded one in an economy-size bottle to save some cost.

Some carwash soaps include a wax, but it’s better to apply a good wax separately to make sure the paint gets real protection. Paint will pick up bits of road tar and asphalt, dried bugs and other debris that’s hard to remove with regular car-wash soap.

That’s where a good bug-and-tar remover will pay off. Usually, bug and tar removers require some extended soaking and/or a bit of elbow grease for hard-to-remove debris, so do it after you wash the car but before waxing.

A microfibre wash mitt will hold lots of sudsy water and allows dirt and other loose particles to be captured in the fibre and whisked away from the paint.

The mitt is usually made up of soft, fluffy fibres that absorb lots of water and provides plenty of nooks and crannies for dirt particles to get trapped in.

It’s also easier to get into tight spaces, because it’s a mitt. A traditional sponge can allow dirt to get caught between its surface and the paint, scratching the surface. So that’s another item to get.

Use a clean, lint-free cloth that won’t scratch the paint. A chamois or terry cloth towel have long been the usual fare, but now the preferred choice is waffle-weave microfibre towels.


The wheels are the dirtiest parts of your car. Road grime and brake dust, coupled with dirt and sand can cause corrosion and permanent damage to the wheels. That’s why a dedicated wheel cleaner and brush is more effective.

There are spray-on products that claim to need little or no scrubbing. Simply spray on, let it sit for a bit, and then hose it off. These are generally effective at removing brake dust and dirt, but getting the wheels perfectly clean without some scrubbing is not possible. Keep a separate sponge or old mitt handy to use just on the wheels and tyres.


After washing, protect the car’s paint finish by applying a good wax or other sealant. Do this when the paint is cool and be sure to use only clean, non-abrasive cloths and pads. Liquid waxes are easier to apply and provide the same protection as harder types, so pick your own poison off the shelves of the accessory shop.

Wax one section of the car at a time. Use a foam or microfibre applicator pad to spread a thin coat of wax using small, circular motions. Let the wax dry for a few minutes, until it’s hazy, then buff it out with a microfibre towel.

So do you use a wax or polish? Essentially, a wax or polymer sealant is a protectant that’s applied over the paint to protect it from the elements. Use it on a perfect paint surface. If your paint is a little dull and you want to restore its shine, then you use a polish.

Polish is often formulated with a very fine abrasive that removes a slight amount of the lacquer finish in order to smooth the surface and help make a dull finish look new again.

If the car’s finish is really dull, oxidised or marred by fine scratches or swirl marks, use a different sort of polish. These are formulated with different levels of abrasives - from mild to aggressive. If your paint is this bad, leave it to the professional to polish and wax.


Sprucing up the exterior trim, fixing scratches, restoring headlights, or quick everyday touch-ups are sometimes necessary.


Long-term dirt and gunk can eat into the paint and leave permanent defects that can be removed only by sanding and repainting. Sometimes you may find products to match your paint if you need minor touch-ups, especially if the damage is limited to a few spots or scratches.


New cars are covered in black or dark grey plastic trim, and the sun’s UV rays can cause this trim to fade. A dedicated plastic-trim cleaner or restorer may be able to spruce it up again. These are used as you would a wax (a section at a time) and need regular application.


This is a relatively new development. Car headlamps used to be glass, but has since been replaced with plastic 10 or so years ago.

Many car headlights gradually haze over due to the sun’s UV rays, cutting down illumination and making it harder to see at night. The solution is not your toothpaste, although it may be used in a pinch.

There are dedicated headlamp and plastic polishes which last longer and protects the plastic. These are also polishes, so use the same techniques (or follow the instructions on the product).

Next week we’ll look at sprucing up your interior. Have fun making your car look new again!

Send your questions to askmechanic@nst.com.my

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