I tried the foil route, but then a buddy pointed out I am using something conductive to cover electronics while spraying it with water - after that I switched to saran wrap/plastic bagsI will cover the small electrical box and alternator with aluminum foil. Why foil?
Shouts out to the Citrus Multi Surface Cleaner. Stuff is killer. I use to to clean off sticker residue or oil/grease all the time. I also use it to clean off my RC cars - spray it down and use compressed air to blow it dry. So versatile and useful.I use Griots citrus multipurpose cleaner and agitate with a brush. It comes in an aerosol can so couldn’t be easier. Cheap, too. Under $5 I believe.
Disconnect and remove the battery before hand. Put a garbage bag over top of the block, maybe over the air intake as well. This will cover off all the parts you have highlighted from water during spray phases. Clean underside of hood first. Spray with water first, then use spray bottle with soapy water and brush to target dirty spots. Do same thing around edges of the bay. Carefully remove garbage bag, you can dump the water towards the front of the bay if you want just avoid the alternator maybe. For anything under the garbage bag, can go over after with light soapy water spray and rub down with microfibre cloth. Just make sure you dry out any left over water from areas around electronics.I tried the foil route, but then a buddy pointed out I am using something conductive to cover electronics while spraying it with water - after that I switched to saran wrap/plastic bags
As for the original question, I cover most of the easy to access connectors and obviously the intake/alternator when washing my bay. I know the connections are watertight, but for an extra 5 minutes of work I can be sure I am not squirting water into the back of the connector or anything either. Peace of mind.
I attached a pic highlighting the areas I tend to cover with a part of a plastic bag - i'll rip a bag into shreds and just tie it around a bit. Since the connection is already water tight, you are really just kind of shielding it from direct streams of water; so you don't have to go crazy covering every last inch up. There are also a few on the rad you can cover - once thats done you can pretty much wash the bay down however you'd like. I almost always use a power washer from 3-4 feet away, i've used garden hoses as well though.
I usually use an auto-detailing All Purpose Cleaner diluted and just go over the whole bay with some brushes; I've also used the gunk engine degreaser ; which is great at cutting through any thicker stuff
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It's not so much to protect the battery from getting wet, it's in the off chance that you get water into something that has battery power flowing to it (like the ABS electronics mounted to the firewall). But then again, if you're not using a pressure washer there probably isn't much of a chance of this happening anyway.I agree with what MrFancypants has said. Although I question the need to disconnect the battery. My car has a cover over the battery & I can't see how water could ever affect it. I've cleaned many engines over the years & haven't disconnected a battery yet.
I always clean my engines. with a little here & there cleaning so no heavy duty cleaning is needed. Pretty sure using a power washer could cause a lot of damage. As Fancypants says, even a weather pack electrical connection could have water forced into it.