DON'T use WD-40. WD-40 attracts dirt, and that'll cause rubber parts to degrade faster. Use 303 Aerospace Protectant. That's some good stuff, it cleans, makes the hoses look good, doesn't attract dirt, and protects them from heat damage.wuzoo said:slow down
You need to wrap all sensors and exposed wires in cling film. Then cover the engine in trafic film remover ("TFR" an industrial strength degreaser) then clean with low pressure water. When dry (maybe use a leaf blower) you cover the engine in wd40 (not neccessary) & a high gloss engine dresser (neccessary).
I've known two people who have wasted there uber expensive engines by blasting them with water, the costs where $$$ excluding lorry costs i.e. loading a car onto a lorry then driving 300 miles to fix it. The electronics needed fixing as well. Say $1000 to snort out a session with a hose
If if needs done, get an 'expert' to do it. If he fries your ECU its his fault. He (should) pay the for the damage
Even better, get benz to do it!
please, dont destroy your car by following poor advice!
BTW spraying cold water onto a warm engine will destort hot metal. If you spray cold water onto a hot engine block then there is a good chance of affecting said block, aluminum or not. The 'learned' say to run your engine whilst washing your engine, as the heat evaporates the water meaning your spark plugs should not misfire. Ignore heat for 'drying' use WD40!