Cleaning the engine. Why would anyone do that? What are you showing it of to you mother-in-law?
It has "very little" to do with showing it off!
Here is a few reasons:
1) Before working on, to remove dust. Which dust is; fine sand. When we remove the intake manifold this is super important. As any dust into intake ports, will compromise compression. We work at cleaning area between intake-man to head valley. Using Air pistol before, during and after getting wet.
2) Same holds true for spark plugs R&R. Here we must use extra care when cleaning head covers, especially if coil boots are old (shrunken). We do not want to wash dirt with water into spark plug tubes. It's also best to blow out spark plug tubes with air pistol, before pulling plugs.
3) Clean off oil to help locate leaks and or confirm.
4) While working in engine bay on any part. We need clean during assemble. Or we're more likely to get grim into engine, and in threads of bolts & nuts.
7) Reduce corrosion of parts from salts & pollutants.
8) Cleaning radiator fins.
9) For inspection purposes.
This is one reason we clean with engine running/warm, than drive to dry.
When I had a running engine power washed (without my approval) at a shop, it fried the distributor cap and rotor by forcing water into this high voltage area. I would never power wash a running engine. After washing, take the vehicle on a long drive to get it good and hot and dry it off.
We don't have distributors. Those and its coil, were replaced with COP and electronic IG systems. But when we did have distributors in the old muscle cars, we cover them with plastic bag or foil. When they did get wet inside cap. We just pull the distributor cap and dry it, rotor and points. No need to replace anything.
There are areas to use caution like alternator, fuse box, fire wall & hood deadening barriers, etc. But for most parts, the Land Cruiser handles washing very well.
BTW:
Make sure to keep undercarriage including brakes clean. Always drive to dry afterwards!
