The engine bay on my 1999 Land Rover Discovery 1 project wasn’t that bad, but could benefit from a freshen up. My approach to this is simple: don’t try to do it all in 1 cleaning.
Why? You can minimize having to do too much prep work or soaking the engine resulting in more problems. I prefer to do a series of smaller washes, slowly getting the 18 years of grime off.
First, I used these two products, both available via Amazon (click the names)
Ensure your engine is completely cool, all the way to the TOUCH. I parked the truck where I planned to do this the night before, so in the morning, I didn’t even need to fire it up. It’s important to note, I would avoid doing this on your concrete or asphalt driveway, as the cleaner might mess these surfaces up. I use the gravel access driveway to the rear of my garage, off the asphalt.
Spray the Gunk Feb1 on. I would avoid any electrical areas but really foam up the other areas. Below is a pic during the process.
Next, take a brush and brush the surfaces that are really grimed up. Let this foam sit for at least 15 minutes.
Once it sits, take your hose and rinse it off. Avoid soaking the entire engine using the jet nozzle. I use the shower nozzle feature and in a sweeping motion, go back and forth over the engine to get all the foam and grime off. During this, I use a sponge to get into crevices.
Once the engine is 100% dry, I use the S100 engine brightener on the engine for the finishing touch.
I’ll do this 1-2 more times before winter, to continue to get the grime off. I simply find avoiding drenching the engine all at once is the safest approach. Below is the after photo.