What is the best way to clean an old motor while still in the car?

I am getting to the point where I need to start cleaning the motor on the XJS. However, with 30 year old British wiring, and 12 cylinders worth of ignition and injectors, I am a little nervous about just lightly taking a pressure washer to it. I'd rather figure out the proper cleaner that I can spray on and then lightly rinse off without damaging any electrical components. I plan on going through everything, but don't want to make work for myself in the process. Does anyone have any tricks?

Have it professionally steam washed?

Do one section at a time.

Take off stuff that is easily accessible like wiring or accessories.

I use a de-greaser like purple power or simple green with an old paint brush to spread it around. Brake cleaner also works great for more caked on stuff.

You can use a small brush with rustoleum paint in a can to make aluminum or black parts look new while on the car.

A wire brush on a drill works great for cleaning aluminum.

Cleaned in the car... One of my past challenge cars

In reply to pimpm3:

So was it the Purple Power, or Simple green that did that to your valve cover?

i always did mine while running. that way if it dies out, or starts running poorly, i know where i was spraying when it died/stumbled.

i don't recommend this, mind you, but its they way i do it.

-J0N

I regularly clean oiled up BMWs at work after fixing leaks.

I normally spray the whole engine bay area down with heavy floor soap/degreaser in a pump sprayer(weed killer sprayer from HD or Lowes).

Then run for 20+ min to get hot, while running continue spraying everything down. Stop for 3-4min at a time to get hot again and spray and repeat.

Finish up rinsing with a water hose.

Caked on stuff can be hit with brake/parts cleaner if real stubborn while spraying w/ degreaser.

This should get you most of the way there.

Use hot water to rince and if you can heat what ever you are spraying on. I use so stuff called oil eater. Will cut through most anything when heated. Using I on a warm motor for even better results.

Cause no one else said it. I love gunk brand foaming engine cleaner. I personanly will use bags and tape to keep water off important things like my exposed air filter and frail distributor, spray the hell out of the engine cleaner let it sit then hose it off like you would water grass. Get original gunk or the hd kind I never had good luck with their weaker can. Stuff does wonders, eats through grime then just hoses off. Whatever it doesnt get bust out the carb cleaner and or degreaser of choice. I also like to leave the hood open facing to sun to help dry it out

Hungary Bill wrote: In reply to pimpm3: So was it the Purple Power, or Simple green that did that to your valve cover?

... a little elbow grease goes along way Paint helps too

I do hot water, warm running engine and Simple Green.

I personally wouldn't bother with pressure washing the engine and bay because of the electrical components. I usually just use engine degreaser, in rare occasions I will use car wash and a scrub brush and wash it off.

Warm engine, tone of purple power, scrub as best I can with a wheel brush, high pressure hose off repeat if needed.

Warm engine, original formula gunk engine degreaser, let soak, blast off with garden hose, repeat as needed.

I've never done engine cleaning hot. Don't you have to worry about cracking stuff?

And no one has said "get out of the car you lazy bastard"?

In reply to Dusterbd13:

By the time the soaking period is over and the water hose comes out things have cooled enough it's not an issue.

Menards once sold this stuff called "Steam Clean", it sprayed on like Gunk foaming cleaner but it cleaned everything. I would get it warm spray the foam on then rinse off after five minutes. My driveway would be cleaner where it rinsed off also. May be a reason I can't find it anymore lol.

Gunk original engine degreaser on warm engine. Marinate for 20 minutes... Blast gunk off at car wash.