Best way to clean engine bay?

[greeny46]

Evening all having had quite a bit of new sensors added lately on my fabia 1.6tdi estate and noticed it's rather grimy under there. I'm looking at getting under the bonnet and giving it a proper clean meaning pressure wash etc.

Any suggestions on what I need to cover/avoid and best stuff for cleaning an engine bay?

Thanks in advance.

[Ootohere]

At least less risk with a diesel than a petrol, but you will get a clean engine and by this next winter maybe a corroded looking one.

Do it with a good cleaner / degreasing spray, maybe Muck-off for mountain bikes, or Gunk. and use a paint brush cloth etc and clean up, not a power washer or the likes.

Just my opinion.

 

I like to oil lightly the engine alloys after cleaning, stop the horrible alloy whiteness  / corrosion that comes after cleaning engines and removing the protective coating. 

I use Tesco Tyre / Rubber renovator on plastics. 

 

eg   Corroding horrible alloy.

Edited 20 June, 2018 by Offski

[alfalincs]

I'm amazed anybody even considers using a pressure washer under bonnet with so many wires, connectors, and electronic components. It was a regular source of problems when I worked in vehicle warranty thirty five years ago and under bonnets have become far more complicated since then.  The time honoured way is to use a paintbrush and jizer or gunk and just do it a bit at a time very carefully using a plastic jug to tip warm water over the bits you have treated, carefully avoiding electrics and air inlets.

 

It may not look quite as 'clean' as a jet wash, but you stand a far better chance of the car still working afterwards.

[Kobayashi]

Autoglym engine bay cleaner, then autoglym vinyl rubber for plastic bits. It can be done by hand not super perfect but good enough

[krigl]

Why would you even clean the engine bay? I understand if you are off-roading and mud is in there, but from normal road use I have never done it. Leave it until it is working, if something needs replacing, then clean the area around working area and that is it. There is already enough water going through the engine bay as it is, why put more in with some aggressive cleaners, that hurt plastic parts and wiring looms. 

 

If I buy a used car, I rather see a dirty engine bay and see all potential leaks, than a clean one that is in most cases hiding potential problems. 

[mrgf]

I have heard of people using WD40 and/or similar sprays. Clean the metal and plastics with low chance of damage. Spray, wait a few, wipe. Slower process but do-able. The only issue I am aware of (And I am happy to be corrected) Is that whilst in solvent form, it is HIGHLY flammable. So do be sure to let the stuff dry out properly before starting the engine and apply to either cold or just slightly warm engine. 

 

(I take no responsibility if you try this method and set fire to your car, garage and house, etc. You pays your money, you takes your chances).

 

That said, I would rather try this then pressure washers!

[kenfowler3966]

I actually spray parts, joints, seams screws etc, under the bonnet likely to corrode with protection, the last thing anyone should do is clean under the bonnet for the reasons above.

 

EG we had a 1983 polo from new which my mother bought, and then passed arounds the family until 20 years old  when a minor accident wrote it off as no residual value. No corrosion or damage evident around engine bay, and was liberally sprayed with various protective substances.

 

I replaced it for my wife when it was passed on to my brother in law with a Polo coupe from 1994, bought 3 years old from a dealer. They had cleaned the engine bay and it looked pristine when we bought it. Within a year all sorts of corrosion was going on under the bonnet. We got rid of the car after a couple of years, mainly as too small with another cost centre due, but also because of its rapidly deteriorating condition. Cleaning under the bonnet removes oils and grease protecting the engine, and also all the wax and other protection to the bodywork an in the welded seams etc.

[Ootohere]

This is my 1999 Jimny.  Under 60,000 miles and now only does around 500 miles a year.

So 19 years old.  All the wiring was sprayed with Finnagan Waxoyl when new & white grease in various places and then dirt & cobwebs allowed to gather.

Not really had anything done to it for a few years, i must give it a tidy up.

There is some corrosion showing near the bottom brackets of the radiator as i looked while taking these pictures.

(This one will be retired when i get a New Jimny next year. It will get the same treatment on the first day i get it.)