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Cleaning engine bay

5 Step Guide To Detailing An Engine Bay

Enthusiasts who like to display their vehicles at car events will be the first to say that a smart, clean engine bay adds an extra layer to that pride in appearance pleasure. Most regular drivers though scarcely see their engine from one service to another, even if they spend time detailing the exterior.

Well, there are some very good reasons to give the engine bay as much attention as the paintwork, so why not make it a part of the detailing regime? Here are five suggestions:

Why Detail Your Engine Bay

Routine engine maintenance jobs, checking the fluid levels and the like, are made easier if the engine is clean. The area under the bonnet is largely open to the road and can get very dirty very quickly while also accumulating leaves and other detritus. This in turn can lead to the degradation of exposed components. A clean engine bay makes it easier to spot leaks, damage and wear and tear too.

When You Should Detail Your Engine Bay

This important area should not be overlooked. It is best to clean under the bonnet every three to six months, depending upon usage and conditions. It is, after all, the heart of the car and it pays to keep it healthy. The first time might be hard work, but subsequently that effort will make life easier thereafter. Here are a few items the engine bay detailer will need:

What You’ll Need

As with any maintenance job it pays to be prepared and have everything needed to hand. Ensuring personal protection from contaminants and fumes, you will need:

  • Degreaser or spray on all purpose cleaner
  • Small detailing brush, ideally with a long handl
  • Pressure washer or hose pipe
  • Microfibre cloths Drying towel
  • Engine dressing to finish
  • Cling film or tin foil to protect sensitive areas.

Preparing Your Engine Bay For Cleaning

It is simple to remove any plastic engine top covers. Clean separately.

This is where the cling film or tin foil comes in handy. Electrical wiring runs throughout the vehicle and there are exposed electrical connections under the bonnet. Engines are sturdy and resilient but better safe than sorry. Wrap those components to avoid soaking. Note: Always ensure the engine is switched off when touching electrical components.

Clear away any top level loose dust and rubbish like accumulated leaves that rot and can block under-bonnet rain channels.

Give the engine bay a light water wash. If using a pressure washer then ensure it is on a low setting. Alternatively use a gentle flow hose. Make sure to get down to the wing and firewall panels. This will help loosen hard-to-shift grease and road dirt, prior to using a degreaser.

Top Tip: Do NOT attempt to clean the bay when the engine is hot. Anyone who has had an engine burn will tell you that this is sage advice. That said, some detailers like to slightly ‘pre-warm’ an engine to aid the cleaning process. Remember though that modern engines warm up fast.

Degreasing The Engine Bay

A cautionary note here: Take extra care when applying degreaser, ensuring that it doesn’t get on exterior paintwork where it will likely strip away any car wax or ceramic coating that may have been applied. On balance it might be an idea to work on the engine bay first!

1. Using a quality degreaser or a product suitable for engine bay cleaning and starting from the bottom up, spray and leave for a couple of minutes to allow the product to work. It doesn’t matter if the engine bay is still damp at this point.

2. Take the detailing brush and work the degreaser into the dirt, concentrating extra effort on especially bad areas. An old toothbrush or specialist detailing brush is always handy for those hard-to-get-at areas.

3. Some areas can be inaccessible which is why a long handle comes in useful. Just because you can’t see it doesn’t mean it does not need cleaning.

Top Tip: It might be easier to approach the lower parts of the engine bay around the sump and wheel arches from underneath. If this is possible, ensure that the vehicle is on ramps or jacked using axle stands and wheel chocks, just as you would with an oil change. It’s going to get messy by the way, so wear old clothes or overalls.

How To Wash Your Engine Bay

1. Rinse away the degreaser with low-pressure water.

2. Wash the engine bay again using a car wash product. A spray bottle might help. Use a wash mitt retained especially for this job and not used for paintwork.

3. Rinse again. Repeat if necessary until you are satisfied the job is as good as it can be.

Drying Your Engine Bay After Cleaning

1. Remove any protective material from electrical components and discard. Allow the engine to air-dry. It might be an idea at this point to start up and let the engine warmth finish the job quickly, bonnet up.

2. Speed up the drying of the top level engine block and components with microfibre cloths or a drying towel. Some canned air might aid getting rid of any small pockets of water.

3. In the past, car owners would use light oil or products like WD-40 as an additional level of protection but with modern engines this is no longer worthwhile. It just attracts dirt. Regular cleaning is all that’s needed.

Dressing Rubber & Plastics In Your Engine

At any ‘show and shine’ motor event, the engine bays are often as smart as the exterior paintwork. That’s because the owners have gone the extra distance and used a dressing to make components shine, giving the whole a uniform appearance. Make sure to use a product that is designed for the job, in that it can withstand high under-bonnet temperatures.

Any under-bonnet painted surface might benefit from a spray sealant. Wax alone won’t do as the area will be too hot. To shine up the plastics and hoses you could use a good quality rubber/vinyl protection. This will help keep hoses supple and avoid cracking. Finish off with a good buff-up with a microfibre cloth. Stand back and admire your handiwork.

In Conclusion

Detailing an engine bay is not a complicated task. For an older or well used car, initially it will be more arduous and might need extra cleaning but once done, in future regular cleaning will be much quicker. It will also make working on the engine a cleaner and more pleasant experience. Certainly, your local servicing engineer will thank you.

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