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How To Clean Your Engine Bay!

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#1 hulk_slogan

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Posted 12 May 2015 - 10:03 PM

How to clean your engine bay!

Summer approaches, and it’s likely that the only part of your car that’s not clean is under the hood!
Show it some love…

There’s a couple of ways to clean your engine bay, and loads of advice and info online, but here is how I go about it.
Firstly if your bay is covered in dirt then be prepared to have some dirt and water splash out over your windscreen, wings and bumper, so it’s a good idea to clean your engine bay before cleaning the exterior of your car.

Secondly and most importantly only clean your engine bay when it is cold.
For obvious reasons but I’ll mention them anyway!
You could easily burn yourself or trap your hands in moving parts.
You’ll also find the heat of the engine could dry any water or product you are trying to use to clean it faster than you would like.

There are two ways of cleaning the engine bay, ‘waterless’ or with a hose, which produces wet stuff..
You will find people who swear by jetwashing an engine bay, and people who wouldn’t use a jet washer if their detailing reputation counted on it!

Firstly I’ll talk about using a hosepipe or jetwasher to clean the engine bay.
If you want to use water to aid in cleaning here are some things to bear in mind.
You will get a more thorough, faster clean.
However there are things inside the engine bay that don’t mix with water so well.
My advice when using water to clean your engine bay is as follows:

Start with the engine cold and switched off.
Remove any leaves, twigs, spider webs etc…
Cover all electrical parts in the engine bay, and anywhere water should not be allowed to enter.
These might include:
Electrical plugs.
Air intakes.
Spark plugs and their pit in which water will collect and remain.
Any wiring which goes through your firewall/bulkhead.
If in doubt, just cover it!

If like me you have several runs of amp cable running from battery through the firewall, then make damn sure the point it goes through the firewall is sealed, and any inline fuses are also covered.

To cover any of these areas you can use waterproof tape, duct tape etc, or I prefer to use cling film as it can wrap around and self seal most places you’ll need to use it, then simply take it off after your done using water. Avoid using kitchen foil as it’s a metal and therefore could bridge/short electrical connections.

Once all sensitive areas are covered, we can begin cleaning.
My advice is do not use a jet washer or any powerful water propelling devices!
I previously used my karcher pressure washer but left it turned off, so the water was under the same pressure as a normal garden hose.
You could also use a normal hose with no head, and simply place your thumb over the end of the hose to create a fine mist/spray of water.
You could also buy a handpump water sprayer and use that.

The effect we are after is not to drench the engine bay, but just mist it with water until it starts to run, making sure to use your common sense and stay away from over watering areas that you have covered.

Once wet, we can start to use products to get the engine clean.
I use Autoglym Engine Cleaner & Degreaser but you could also use something like an APC (All Purpose Cleaner). Make sure to follow the instructions on the product.
Spray the product on, agitate if necessary and rinse off using the same method as when initially rinsing the engine bay. Only need to use enough water to help the product to run off.

Make sure all filler caps are securely on!

Work section by section. For example it’s a good idea to wet a small area first, spray product on that small area, agitate and then rinse. Repeat until the entire engine bay is done.

Start with the underside of the bonnet, because dirty water will drip over the engine while doing this.
To help agitate the product and get into hard to reach places you could use detailing brushes, or toothbrushes. Be careful not to scrub painted surfaces as I’ve seen detailing brushes with fairly soft bristles eat through the paint quickly!
Its also a good idea not to use an old toothbrush that has had toothpaste on it.. You’ll be amazed at the toothpaste residue it could leave even if it seems clean..

Before moving on, rinse off any overspray of dirty water from your bumper and wings/windscreen.
Once all is clean, remove everything that you have used to cover sensitive parts with.

The next step before dressing the engine bay is to get it dry.
You could use a chamois or microfiber drying towel  for easy to reach places, concentrating on getting any pools of water dry (for example, around the spark plugs). To help wick water away from places like this, try some kitchen towel.

You can then double check all tape/cling film is removed and start the engine which will help to dry the rest of the engine bay.
Once dry you might need to give certain areas a quick going over with a quick detailer and a microfiber if you’re anal like me..

Now, you could use a metal polish to polish some of your metal piping, maybe give the painted areas a little polish and a wax, depending on how far you want to go!
I usually just dress the plastic and rubber areas as my engine bay is standard and theres not much to show off, I just like it clean.

To dress the plastic parts such as battery cover, fusebox, airbox, filler caps and reservoirs I use simple trim restorer. My product of choice here is Megs trim restorer gel, but you could use a back to black bumper spray, or an interior detailer such as Megs interior quick detailer.
I usually apply with a microfiber or applicator pad, leave for the recommended time and buff off.
I also use this product on the engine block itself.

For rubber parts, such as hoses, spark plug covers, wiring, induction tubes, and rubber seals I use Meguairs tyre gel. Same application as the previously mentioned plastic parts!

To get behind or to get the entirety of tubing clean/dressed, if its easily done you can unclip them from their housings. Just remember to replace them after you are done.
A product also well used for dressing engine bays is Aerospace 303.

Now, if you prefer to take the safer yet more time consuming route of not using water, I have had good effect using a waterless wash product. It is basically a spray on, wipe off product designed for cleaning your car with just the bottle of spray and a cloth.. Not many uses for us detailers!
What I did is effectively follow the same procedures as mentioned above for using water, except just not using any water and instead using the waterless wash product which just needs to be wiped dry and not rinsed off. I think my one is made by Turtlewax, although I believe Megs and other manufactures make it too.

I didn’t need to cover any sensitive areas, because I simply didn’t spray them!
Work in sections and use a new microfiber when the current one becomes too dirty.
You might get through a few with this method!
The upside is that its safer and doesn’t have any real drying time, so you can go straight onto dressing the engine bay!
The downside is, you can only really clean where you can reach your hands..

To clean sensitive areas using this method, don’t spray the waterless product onto the area, instead, spray a microfiber cloth a couple of times and carefully use the moist cloth to clean the desired area.

That’s pretty much it! Take a step back and admire a clean engine bay.. Feels good doesn’t it?!
Watch for the odd raised eyebrow when a mechanic opens the bonnet to find a great looking clean bay!

Here’s my Mk1.5 using the water method:
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Here’s Kays Mk1.5:
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Here is my mk2.5 using the waterless method.
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Any questions feel free to comment or PM, and please feel free to suggest additions/tips to this guide and I will update it to include them!
Cheers all,

This is how I do it. (I do not accept any responsibility or liability if any damage is caused to any car by using this guide).

#2 Rikvdub

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Posted 31 May 2015 - 11:19 AM

What a fantastic write up this it! And some great tips. My focus from looking at the state of the engine bay has never been cleaned!! When the weather gets better I will get my cleaning products out And will post my before and after pictures

#3 keggy

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Posted 31 May 2015 - 08:33 PM

Nice clean engine i prefer the no water method less chance of problems,a job well done.


#4 obasa


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Posted 01 June 2015 - 05:17 PM

All cleaned by using various rags with products

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#5 Jinjoh_ninjoh

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Posted 05 June 2015 - 03:43 PM

heres my attempt from today:

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#6 richard225

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Posted 05 June 2015 - 07:32 PM

good write up I allways use the no water , as water and electrics do not mix

#7 listy

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Posted 06 June 2015 - 08:24 PM

Anyone recommend best product to use?