Make your engine sparkle
How and why to give your engine bay some love, plus some of the best products for the job
Your engine is a badly treated old thing. Run through endless cycle after cycle, getting hot, cold and wet. Yeah sure, you top up the oil occasionally, throw some nice juicy fuel in and change the belts when they squeak, but your engine deserves better. Take one hour of your time once a month or so and give your engine and its friends under the bonnet (hood, for you Americans) a good clean and a quick visual check. It's not only an activity to please the eye but also one that may save you from mechanical issues down the line.
Your engine bay isn't on show very often, so wouldn't it be nicer if every time you open the bonnet you are greeted with some nice shiny metal and black plastics, rather than leaves, dirt and oil stains? You may think that cleaning under the bonnet it is a waste of time, being that you spend little to no time in there. But read on to find out why you should be giving it a little more attention, plus I'll run you through the easiest way to make it shine and what products to use.
Why you should clean your engine bay
Cleaning your engine and surrounding components will give a nice clean canvas for any oil and other fluid that decides to take leave from its responsibilities inside your engine. Any leaky gaskets or caps will soon show themselves in a clean engine bay, with stains much more obvious, along with any other damage to pipework or covers. I feel that a cleaner under-bonnet is a better and nicer place to work. I am much more inclined to have a look around the bay when clean and get my hands into the crevices to undo bolts when I know my tools won't come back covered in all matter of filth and fluids. I think a lot of you will feel more inclined to get on with maintenance and servicing more readily if you're greeted with a clean work area.
This ability to spot leaks and issues more easily could save you some big money down the road (engine failures due to low oil get very expensive), as well as getting you more in-tune with the running of your vehicles mechanical components. Dirt in the engine bay is also available to be sucked up by air filters and is likely to fall into open caps and cavities when performing maintenance, having clean surfaces will stop any of this, leading to your engine running carefree for longer.
For those of you who attend car meets and shows, you will know the embarrassment of having a dirty engine, while others show off their gleaming, perfectly detailed mechanicals. You don't need long to clean up the area, even a quick clean will leave you more confident in your show piece and more satisfied at the same time.
When it comes time to sell your car, you may benefit from having cleaned all areas also. Prospective buyers will likely appreciate the time and effort you have gone to in keeping difficult areas clean, ones that are usually neglected. A car that is thoroughly cleaned is always the sign of a careful and considerate owner, ignoring the old adage that a clean engine bay is hiding leaks (this is often far from the truth; leaks will soon reveal themselves after a quick heat cycle).
A simple task that requires minimal time and expense. Now you've been convinced that you should clean your engine bay, you'll probably want to know the easiest and best way to get started...
Process
Get rid of those pesky leaves
To start, clear the engine bay of any loose debris. This means clearing any leaves, twigs or other loose rubbish in your engine bay (and scuttle panel). Take this time to have a good look at the electrical connections and check for any leaks already present. Ensure that the engine is cold before cleaning and then set about covering up any exposed electronics.
Cover those electrics
Use cling film, tin foil or plastic bags to cover electrical items such as the fuses, alternator and distributor (where applicable). Older or modified cars may also need intakes or carburettors covering to ensure large amounts of water do not make their way into the engine bay. Modern engines will likely have most parts covered with plastic shields. Engine bays are subjected to water on a regular basis so should stand up to a light spraying just fine, as long as you aren't using too much water or a pressure washer.
Once all relevant items have been covered, spray down the engine bay with a small amount of water at a low pressure. Follow this by spraying the entire bay with a de-greaser or APC (all-purpose cleaner). It's important at this stage that the engine is cool to ensure the cleaning solution does not dry and leave the dirt more securely in place than before. Give the solution time to do its thing (if required by the instructions) and agitate with a brush or sponge to get the dirt off the major components. A small brush may be required to get into some fiddly areas. In the photos I am using a simply wheel cleaning brush, this works fine but I would recommend a detailing brush for more accuracy and a deeper clean.
Now spray off the engine bay with water once again, ensuring you have cleared all the cleaning solution off. Use the minimal amount of water possible in the process to minimise the chance of any water damage to electrical components. Once the area is clean, wipe dry with a microfibre towel or terry cloth, focusing your attention on any water pools that may have congregated in crevices around the engine bay. Now remove the covers you placed on the exposed electrical parts and dry off any water that drops off these covers, also ensure to dry any areas of over-spray on the cars paint, de-greaser and APC solution are not kind to paint if left for long periods.
Optional finishers
For those of you who want to go that extra mile there are plenty of products available to further enhance the finish and make the parts under your bonnet shine brightly. Using a detailing spray will give a better finish and should help to hold the dirt off for longer. For modern engines with lots of plastic covers, using a specific plastic-based finishing spray or detailer will yield the best results. Ensure that the areas you are spraying are clear of any dirty water before applying and wipe with a lightly damp microfibre when finished to remove any excess. Sealants can also be applied at this stage for a longer lasting finish, these will add a layer of protection to the parts in the engine bay, keeping the dirt and grime off for longer, though a regular clean will suffice unless you plan on leaving the under bonnet uncleaned for long periods of time.
You can even go one step further at this stage. Some parts in the engine bay that are made of metal may be susceptible to rust, if you (or a potential buyer) see any rusty metal parts in the engine bay this may spoil the look and make the car seem poorly treated. So to give your car that new-car finish, take any offending rusty parts off, remove the rust via sanding or other rust solutions and apply a new coat of high temperature paint. Plastics can also be removed and brought back to life with a lick of paint or specific plastic restoration products.
These are optional steps and will incur extra cost and time on top of cleaning the general engine bay area. For those of you who are all about the detailing life this may be worth the extra effort, but for the majority a simply clean will yield maximal results for minimum time and money spent.
Tips & best products
Stay away from supermarket cleaners and washing up liquid
One of the most useful items you could have to hand for this job is a pressure sprayer, one like you use on your garden plants. This will make spraying the engine bay a doddle, with minimum water used, so as not to drown your cars electrics. Using a small sprayer will also prevent water wastage and means you don't have to get the hose pipe out just to do the engine bay. Though that said I would recommend doing this as part of your full car clean every month or so.
I also recommend having multiple microfibre towels on hand; these are useful both to dry the engine bay and also to lay on the car wings. Laying a soft towel on the wing of the car will allow you to lean into the engine bay and reach those difficult areas, without any worries of leaving scratches in your paintwork. This is a much cheaper and easier alternative than purchasing official car wing protectors. Drying the area (including any over-spray) is important to ensure that none of the solution is left to damage plastics or paintwork.
For this job, I used the Meguiars All Purpose Cleaner in the small spray bottle. This solution worked fairly well and it easy to use, without containing too many harsh chemicals that could damage the engine bay plastics or your lungs. If you do this job regularly though I would recommend buying some concentrated automotive all-purpose cleaner formula, this can then be diluted to your favoured strength via mixing with water. These will require less frequent purchasing, better results and money saved in the long term. From forums and articles I have read, both Bilt Hamber Surfex HD and Autosmart G101 are recommended for use in the engine bay, as well as any other greasy areas of your vehicle. These are based on recommendations for UK drivers. For Americans I have heard good things about Simple Green degreaser and Ammo NYC products.
When dressing of the bay for an even better look, use the same products that you would use for your exterior trim pieces. Any of the trim dressing from companies like Meguiars, AutoFinesse or AutoGlym would work just fine. But use whichever brand you like or have available to you, I wouldn't recommend spending a lot on this as you don't see the engine bay very often, so save your money for a nice carnuba wax or sealant to protect your cars paint instead.
So what are you waiting for? Next time you give the outside of your car a wash, give the underbonnet it's fair share of love also. It might just make it look nicer, but it might make you a nice saving on spotting some mechanical issues earlier or making for an easier sale. On behalf of your engine, I thank you in advance.
Please leave a comment with your recommendations, tips and favourite products for cleaning up dirty, greasy engine bays.
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Comments (2)
I find it handy to cut an old cloth into 1 inch wide strips, and use them to clean small gaps, around pipes and wiring looms etc, by holding both ends in a back and forth motion, a bit like flossing your teeth.
Great idea that Chris, will have to give it a try next time myself, thanks