Any tips on solvents for engine bay clean up.
Wow, lots of different chemicals for lots of different cleaning challenges. Good all-around solvents are the citrus based solvent/degreaser/cleaners. Be careful of strength as they can attack paint, plastic, adhesives, rubber etc. Home Depot sells an inexpensive gallon concentrate which can be diluted if necessary. Variants of citrus based chemicals are "Goo Gone" and "Goof Off" which are used to remove sticker adhesives, crayon, tar etc.
Another very good cleaner is called Oil-Flo Safety Solvent:
http://www.amazon.com/Oil-Flo-Safety-Solvent-Cleaner/dp/B0009KKSX0 Highly regarded by the detailing crowd.Other good, readily available cleaners are Spray-Nine (Stronger version of Formula 409/Fantastic), WD-40 and Brake Cleaner (this is also good for removing grease stains from upholstery and clothing).
For rusted steel parts I sometimes remove the piece, media blast and coat with the appropriate material to prevent oxidation. This can be a standard clear paint, high temp clear (VHT paints are great-perhaps for your cleaned brake lines), powder coat or color appropriate paint.
Use a little science (electrolysis) to remove rust with a battery charger, water, an anode and a bit of time:
http://www.youtube.com/watch?v=-8vT2mdXBs8If you cannot remove rust and get to bare metal the POR-15 products are second to none. It's been around for a long time and has a very good reputation in the automobile restoration and marine communities. I just used quite a bit during an industrial rebuild project I oversaw.....we used alot!
http://www.por15.com/POR-15-Rust-Preventive-Paint/products/1/. Mind you, this product can be used on "new" metals, however, proper preparation is required to provide a clean surface with a "bite" for the paint to adhere to.
If you need an aggressive chemical to remove the likes of anodizing an old trick is to use oven cleaner. Let sit for 15 minutes, rinse (repeat if necessary) and you're on your way to bare metal. Again try in an inconspicuous location first.
For cleaning
NON-anodized aluminum (especially cast components) use one of the degreasers mentioned above and then hit with wheel cleaner, let sit, scrub and rinse. These typically come in different strengths so some experimentation may be required to achieve desired results.
To go a bit further into detailing:For the shiny bits, such as screws, clamps, fittings etc which originally came with a gold finish I would remove and find a local business to replate. This specific coating is commonly referred to as Yellow Dye Chromate, Yellow Chromate or Zinc Chromate Yellow....you get the idea. Basically an inexpensive, sacrificial coating to protect steel parts. I have cleared over newly plated parts when out of sight and exposed to the elements.
Hope this helps.