Engine cover grills: how do you clean these!!??

Not sure what you tried, but you can try slowing increasing the PH and letting the chemicals dwell for a few min, then agitating with a boar hair detail brush before rinsing.

Ideally, you can foam it so it can dwell without running before you agitate. If you use something with a high PH (eg, 12), you dilute it down to the desired strength. Then just hit it with pressurized water. If you don't have a foamer or foaming chemicals, then I'd probably just use Simple Green (~9 PH), let it dwell for a few min, agitate, then rinse.

I would not get in there with anything remotely abrasive. No scraping.

If that doesn't work, I'd maybe try a non-acid wheel cleaner like P&S Brake Buster. Same thing – spray, dwell, agitate, rinse.

 

On similar type of mesh/screens on other cars, I've noticed that if you leave a soaked rag/paper towel with your cleaner of choice (e.g. simple green) for a while, it makes it a lot easier to wipe off the dirt.


BTW, does anyone have the paint color code or spray can for touching up minor nicks on the engine grill? I assume the one pictured above and the one behind the rear windscreen are the same paint.

 

Raw and polished aluminum can etch if strong alkaline chemicals are used and left on too long (or not thoroughly rinsed). That's why I was saying start slightly above neutral and work your way up. IMO, Simple Green is safe in this case.

If you have a PH neutral foam, you can mix in a little Simple Green to bump the PH. After it dwells, get in there with the boar brush, then pressure wash off (the low power electric kind, not the high powered gas kind).

Higher quality wheel cleaners have a few chemicals for lifting caked on grime, and because they're used on wheels, they're often designed to be gentle and not ruin the look.

There are other chemicals that can work, but they're more intense, so I'd start with the above.