# First time engine bay!



## centenary (Sep 5, 2010)

My 8 year old 3 series has never had under the bonnet cleaned (Im ashamed to admit!).

Every time I lift the bonnet Im appalled at the state its in. Sooooooooooooo, I think its time to give it a spruce up. Perhaps I'll pay to get it done professonally but I'd like to 'have a bash' at it myself.

There looks a fair bit of road grit on the front sill and wing channels, not to mention other debris such as old leaves and the like.

So, can anyone suggest what would be a good way to tackle this and what products to use? Im not expecting a totally clean bright engine bay but something a bit cleaner than it is would be welcome.

Although I've just bought a Nilfisk C110 Xtra, I dont want to start power washing the engine compartment as I dont know what should be 'bagged oof' to stop water ingress.

Beep, beep :driver:


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## Roswell (Aug 11, 2008)

I find for getting the thick off the plastics baby wipes / flash wipes / any wet wipe really because you can just bin them as you go, for the channels just used some car shampoo / APC again to get the thick off.


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## Jordan (Dec 22, 2008)

centenary said:


> My 8 year old 3 series has never had under the bonnet cleaned (Im ashamed to admit!).
> 
> Every time I lift the bonnet Im appalled at the state its in. Sooooooooooooo, I think its time to give it a spruce up. Perhaps I'll pay to get it done professonally but I'd like to 'have a bash' at it myself.
> 
> ...


good on you for giving it a go yourself!

first off, i'd get some soft and stiff brushes, some degreaser and APC.

use the degreaser on the mega tough bits, like in between the air box cowlings and what not apc for the plastics.

use the soft and stiff brushes as you need them.

if you want to cover anything up, use either plastic bags or cling film on the electrical components like the alternator, MAF sensor, and battery connections.

just make sure you take them off again once your finished!

it depends on how clean and tidy you want your engine, you can spend days going over it with a fine toothcomb, but a selection of brushes are much easier.

As for dressing, use something like A303 protectant, leaves a nice sheen to the bay, and doesnt attract dirt like some products do.

just liberally spray it over your plastics with the engine on, let it heat up for about 30-40 minutes, and then wipe off with a clean microfibre.

easy peasy :lol:


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## Alzak (Aug 31, 2010)

I want to get engine bay done too but I'm to scared that water will damage something


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## TomV6 (Feb 16, 2010)

I've done loads of 3/ 5 series BM's now (under bonnet), & without covering anything up. It's actually one of the easier engine bays to do as there's lots of plastics and the results are very rewarding due to that fact.

My advice- Get yourself a set of envy detailing brushes (or equivalent), some CG Orange degreaser (Or if you have some APC already, that'll do). Simply spray some on, agitate with your brushes, then power wash off with your Nilfisk- Just use common sense about where you spray pressurised water and you'll be fine.

After you've rinsed it thoroughly, dry it off as best you can, then leave it to dry completely by itself. Then just finish off the plastics etc with some 303 Aerospace protectant (or similar).

Job done.


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## Bratwurst (Jan 23, 2009)

Alzak said:


> I want to get engine bay done too but I'm to scared that water will damage something


You'll be fine man... they're built to take water coming in from all angles. Only a few bits you wouldn't want water in, and generally then only when it's actually running.

You should see the bay of my injection mini (carb ones are less electrical), it's jam-packed with looms and bare electrical parts - yet the grille has big gaps that when you're washing it or driving in heavy rain it must let in huge amounts of water, directly into the alternator and ecu connections and about 4 sensors, yet it keeps running no problem.

Air filter inlet / Induction kit inlet is a must - I have an exposed fuse box which I cover with tin-foil - also cover the main engine relay control box... apart from that it's cool. Oh aye, I'll cover the strobe and siren connections too :devil::lol:


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## Alzak (Aug 31, 2010)

I will try to clean engine over a weekend days as I think nobody clean engine before As it looks bit dirty


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## Bratwurst (Jan 23, 2009)

Bilt Hamber Surfex is what you need for serious degreasing power!


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## ratty (Aug 18, 2010)

Might wanna check if you have water in spark plug holes after washing. Can cause misfire and destroy your coil pack(s) fast. Volvo engines are easy to kill like that.


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## Bratwurst (Jan 23, 2009)

Oh yeah, after you've cleaned it, get it started up to check it's ok and also to get some heat out and help drive any moisture out of all the wee nooks and crannies.


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## DG Cruiser (Oct 3, 2010)

had a bash today on 8 years worth of dirt, apc and plenty elbow grease


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## centenary (Sep 5, 2010)

Hey thanks all for the great advice!

The old girl has done over 144,000 miles now so the engine bay needs a serious clean.

Still a bit concerned about water in there though. I dont look under the bonnet much these days except to check fluid levels since these cars arent really ones you can service yourself. So as a result I'd be lost looking for MAF sensor!

Its a diesel btw so at least I only have glow plugs to worry about and not spark plugs!

Beep, beep :driver:


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## aminder (Sep 16, 2010)

I ought to finish mine off, started but had a mission cleaning ready for some paint


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## scratcher (Jul 20, 2010)

After cleaning the bay I go over it all with WD-40 and a cloth.
The WD-40 helps repel and water in little nooks and makes it all shiny too. It seems to help stop the dirt sticking in future, and prevents anything rusting up a little bit. 
Probably better to do it on a cool engine though. And keep it off any alternator belts, etc.


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## DG Cruiser (Oct 3, 2010)

scratcher said:


> After cleaning the bay I go over it all with WD-40 and a cloth.
> The WD-40 helps repel and water in little nooks and makes it all shiny too. It seems to help stop the dirt sticking in future, and prevents anything rusting up a little bit.
> Probably better to do it on a cool engine though. And keep it off any alternator belts, etc.


hvae you tried using aero space 303? i tried some today, i was quite impressed with what it did for rubbers and plastics.


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## scratcher (Jul 20, 2010)

No, I haven't tried that one. I'm pretty new to all this extra-mile cleaning 

Is it a similar kind of product?
:newbie:


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## Bratwurst (Jan 23, 2009)

WD40's more of a 'workshop' material I'd say, and yes while good at cleaning things it tends to leave a very oily film of it's own behind. I wouldn't be too confident of letting it soak into rubber parts too much either as it may degrade them. 303 on the other hand is a protectant for use after cleaning and is perfectly safe on plastic and rubber.


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## scratcher (Jul 20, 2010)

Oh, cool. I may have to look into getting some of this. Would you use it on interior plastics too?

I always make sure the WD-40's wiped away on plastics and rubber bits in the bay, like hoses and covers. It seems to work a treat on silicone stuff to stop dirt reattaching it's self


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## Bratwurst (Jan 23, 2009)

Yeah I've used it inside with no problems.


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