[Wgosma]

Watched a couple videos, couple questions...and give me your tips on this job:

-remove plastic underbelly pan?
-disconnect battery?
-leave engine cover in place?
-cover alternator and other_____components?

Thanks/Bill

[Opie55]

My answer is no to all four questions. I have washed my engine bays on cars many times and have never has a single issue. I do not shoot a high pressure hose directly at the alternator, the engine computer or major electrical connections or other control units, but it will not hurt them to get wet. The main thing you do not want is to shoot water into the air intake. So depending on what you remove, and how the intake is designed on your engine, a plastic bag and rubber band may be needed.

[6MT_Addict]

Originally Posted by Opie55

My answer is no to all four questions. I have washed my engine bays on cars many times and have never has a single issue. I do not shoot a high pressure hose directly at the alternator, the engine computer or major electrical connections or other control units, but it will not hurt them to get wet. The main thing you do not want is to shoot water into the air intake. So depending on what you remove, and how the intake is designed on your engine, a plastic bag and rubber band may be needed.

+1.

I just spray it down in a wash bay from a few steps back to reduce the pressure. Soap then rinse.

Your engine bay gets wet every time you drive on the highway in the rain. The sensitive components like computers are in a dust/waterproof compartment typically. Dust is just as bad as water for computers.

Just don't go crazy and never wash a hot engine, I drive 2 minutes down the street to the wash bay, engine is completely cold (ambient temp) before I leave.

[tracer bullet]

My tips would be -

Wash in the driveway, and just let the hose dribble on it. Remove dirt with a brush - like a wheel cleaner, something thin on a stick or use a variety of shapes.

Tire dressing can make things look decent. Simple green is a good grease cutter.

Use chemicals sparingly and try to avoid the belts and pulleys.

Generally you should be fine but there's always a chance. On my last car I had to replace the alternator the day after I washed the engine, the bearings were suddenly squealing. Coincidence?

Definitely never when it's hot.

[mike_MAN]

You start removing things and other components have the potential to get damaged. Engine bay are generally made waterproof.
Don't need pressure washer but if you use it, pull it back a few inches so it won't dislodge anything in there. I use a degreaser spray (super clean) to spray mainly what is on top but in other areas as well only if I can reach it with my brush. Whatever's within reach is fair game. I use a wheel cleaning brush to get in the small areas, bigger brush for engine cover and intake cover, small detail brush for smaller areas.
Then a gentle rinse off.
It is worth it to dress your engine bay. It protects it and repels dirt so it stays cleaner longer and no discoloration! That's it.

[rolodt]

I usually just use a degreasing spray, brush, then use a damp blue automotive wipe. Then go over it again with a plastic protectant/polish.

[Wgosma]

I gave it a go today…Dry brushed off loose dust then covered motor w/plastic and washed underside of hood, remove plastic to wash compartment. Used Simple Green to cut the dirt. Looks a lot better!

[tracer bullet]

What you did w/ the plastic bag is not a bad idea.

[Wgosma]

Originally Posted by tracer bullet

What you did w/ the plastic bag is not a bad idea.

I saw a guy on YouTube do that when he prepared to wash the underside of hood, a little extra drip protection. 😉

[Insane435]

Here is what works:

1) make sure engine is cool.
2) wrap alternator in a plastic bag
3) rinse with power washer or hose
4) apply APC
5) agitate with a wheel or lug brush
6) rinse & apply diluted meguiars hyper dressing
7) let it dry and you'll be amazed.

[tracer bullet]

Originally Posted by Wgosma

I saw a guy on YouTube do that when he prepared to wash the underside of hood, a little extra drip protection. 😉

One thing too, if it isn't obvious, is that if you go this route the engine covers are super easy to take off and wash with a hose as well. Could even take them off first so they are sitting by when the rest gets washed.

I tend to agree that things can get wet and are designed to take on rain through the grille and splashes from underneath. However in reality very little gets through either, with the radiator in the front and the paneling underneath. Check the engine after driving in a rainstorm and see how dry it actually is. It should be able to handle it, but it isn't a routine thing.

I've cleaned my 135i engine bay only a handful of times total in its life and found recently when I changed plugs and coils that almost across the board they had some rust and corrosion on them. Wasn't enough to actually harm them, but it was proof to me that water can still get into areas you don't expect. It's an N55 same as my X3. Covering things may not be required but I have to say it's definitely good practice.

[CAX3]

Thanks for this thread. I have been thinking about cleaning my engine bay too, but im concerned about the electronics.

[Wgosma]

Originally Posted by CAX3

Thanks for this thread. I have been thinking about cleaning my engine bay too, but im concerned about the electronics.

This was first time I've ever done an engine bay cleaning job, it's simple and pretty quick to do- as long as you don't use a fire hose the car is fine.