Open the Bonnet , Clean that Filthy Engine



It is a bit like wearing your best outfit, and wearing a pair of grotty underpants because nobody can see them. If you really want your car to be clean from top to bottom, you need to clean the engine compartment. Unfortunately, there is a lot you can do wrong, and plenty of problems you can create if you do not do it properly.

Here is how to get your engine bay spotless.

Why bother?

Nobody looks under the bonnet, right? So why bother keeping it clean? Well when an engine is clean, it can cool more efficiently, there is less wear on things like bearings and pulleys, you can quickly spot new leaks and see whether fluids are at the correct levels and there is a reduced likelihood of your engine sucking in something unpleasant and potentially damaging.

Choose a warm day

You want to clean your engine and surrounds on a warm day when the water can more quickly evaporate… water and engines aren’t the best of friends, and you’ll be introducing water into plenty of places it wasn’t designed to be. A warm day will ensure it dries off in the minimum time. Now, there are lots of electrical components under the bonnet, and they are not a great match with water either. So firstly, remove the negative battery terminal to isolate the battery. Warning #1: most cars have a negative earth but some contrary English cars of a certain age have positive earth, so you will need to remove the positive terminal – read your owner’s manual to make sure. Warning #2: isolating the battery may set your car alarm off. Warning #3: disconnecting the battery may play havoc with your car’s computer systems so if in doubt, consult the manual. Use an adjustable spanner to loosen the nut and bolt on the clamp that holds the battery cable on the negative terminal (unless it is positive earth). You will know which is which because the post will have a little “–” or “NEG” on it or nearby (the positive post has “+” or “POS”). Remove the cable and lay it safely away from the post.

Now, grab a garden hose with a nozzle attachment or, if you have one, a pressure washer. Before you let fly with a flow of high-pressure water, mask off the most sensitive electrical components, usually the alternator and distributor. Take a plastic bag, wrap the component (and any you feel nervous about) and seal with tape. Even though these components can get wet in day-to-day driving, they aren’t usually subjected to a direct high-pressure jet of water.

Next, grab a can of degreaser (there are plenty of commercial products available, and they range in price from as little as a few dollars. In my experience, there’s little to choose between the cheap ones and more expensive versions.) Spray away to your heart’s content, dousing anything you can see… degreaser won’t harm paintwork, but it’s a good idea to limit the spray to the underbonnet area. Stubborn areas of muck can be agitated using a soft nylon brush. Tough components like the exhaust manifold may need a firmer brush or a brush with stronger bristles.

Spray away.

Now comes the fun part. Start power spraying the engine bay, working from back to front. Be prepared to get a little messy… there’s almost always a deflection of the spray, and it almost always gets the sprayer! Start with the firewall (that’s the panel below the windscreen, assuming you’re cleaning a front-engined car) and keep the spray moving so as not to force too much water into nooks and crannies where it would not easily come out.

Leave the bonnet up and allow the engine to dry. If you have spotted other untidy things like a heat shield with surface corrosion, you might think about removing the shield, brushing the surface rust off and even using a can of high-temperature enamel to make it look like new.

Do not remove anything you are not sure about, or are not confident you can replace. These will include anything using a gasket, so if in doubt, leave it alone. Wipe off any excess water with a clean cloth and then coat all the rubber components with a light coat of Vaseline or ArmorAll. (Source: seniordriveraus)

Remove the plastic bags and tape protecting the electrical components, reconnect the negative battery terminal and test that the car will restart and run.

Job done. Now you can open your bonnet without being embarrassed. (Source: seniordriveraus)

Did you know?