Engine bay cleaning?

[Jamie2.5]

Happy Friday!

So my 2003 doer upper probably had never been cleaned under the bonnet.

I really want to give it a going over as it’s disgusting I have seen some people other gently hose it down after cleaning or hold a pressure washer at a distance to rinse off.

What are peoples thoughts - is it safe if I cover electrics?

Cheers

[enuff_zed]

Don't think I'd use a pressure washer tbh!
Usually I try not to wash under the bonnet, but if I do really have to then I get the engine running first.
This means the warmth will help a little to keep the electrics dry and it'll also give you very early warning if something doesn't like getting wet.
If possible though, try to clean it with other stuff that doesn't need water sprayed around.

[Old-Duckman]

Happy Friday!

So my 2003 doer upper probably had never been cleaned under the bonnet.

I really want to give it a going over as it’s disgusting I have seen some people other gently hose it down after cleaning or hold a pressure washer at a distance to rinse off.

What are peoples thoughts - is it safe if I cover electrics?

Cheers

Of course you’ll get opinions on both sides of that question and I will not add a definitive one. But there are plenty of YouTube videos showing how others have accomplished the task, some use a hose, others do not. I have always used a hose when doing various vehicles over my lifetime and have never had a problem but I always used a, shall we say, gentle spray not a full pressure blast. Luckily the Z4 didn’t need it so I can’t say that I have experience with this specific car.

I saw a YouTube video where a guy used a pressure washer, I did that on the Z3 I owned before the Z4. It made some weird noises upon start up so I went around to all the connectors I could get easy access to and sprayed them with WD-40. That seemed to do the trick, I may have pulled some of them apart and sprayed them but I don’t recall if I did that or not. I put 60K on it before I sold it so I guess it didn’t hurt anything but I would never use a pressure washer again to clean an engine bay.

[PDJ]

Heavy rain at 70MPH is going to find its way into the engine bay, so a gentle running hosepipe will be ok
Some of the aggressive cleaning products would do more hard than clean water.
Soapy water brush sponge and care is the best way.

[Brouse]

In terms of products, Autoglym Engine and Machine Cleaner was revelation for me, spray on, rinse off. I used a pump spray bottle with warm water to rinse off and then a back-to-black style product for airbox etc and Quick Detailer for other areas (underside of bonnet etc.

[buzyg]

Always just used wipes on mine. But then it's never really got that dirty under there. As said the engine keeps rain and under body spray out at autobahn speeds, so a hose should not cause issues. But never tried it myself.

[Jamie2.5]

Thanks guys, I don’t intend on making it a regular thing the previous owner lived in the middle of countryside on a farm so it’s just filthy, just want to do it once il cover the electrics and go for the hose option but the tip of running it first for warmth is a good one il only donut on the next red hot day…..watch this space I could completely f*** it up haha

[nick_l]

When I wash mine I make sure it’s cold. Cold water on warm parts may cause unnecessary shock. Cover your alternator with a plastic bag. Jet wash is fine, just keep a good half meter from the nozzle and the engine.

I usually start the with underside of the bonnet first (no point cleaning the engine then washing the crud from the bonnet onto it)

Snow foam and agitate with a brush. Rinse. Then do the same with the engine. I mix a snowfoam / citrus cleaner (for a bit of added cleaning power) snow foam the engine bay. Agitate again with a brush. Rinse off. Dry with a half decent towel. The apply a trim dressing.

[PeteyZ4]

None of mine have been bad enough to need hosing so I just use waterless wash and wax.

Chrisfix did a video which is worth a watch though.

https://youtu.be/PRSoRkM8GcM

[Benderloch]

I use bilt hambers degreaser at 10% then agitate with a soft brush then wash of with my pressure washer with the pump off. This give a gentle and controllable water flow, works well for me.

[Nick W]

I use Autoglym Engine And Machine Cleaner, scrub the nooks and crannies with a paint brush and gently rinse with an open ended hose. While still wet I spray with Autoglym Vinyl and rubber care then just leave it to dry. The result is awesome and lasts for ages.