Beware! Cleaning a car's engine might be illegal in your state as per EPA directive, please check your local state laws before trying to clean an engine as the waste from an engine clean can be toxic and needs to be properly disposed off, there are a handful of EPA approved car wash businesses around that you can take your car to for a clean. If it is allowed in your state then warm up your cars engine shut it off cover the car's ECU, spark plugs and wires with plastic and then either use a steam cleaner or waster in a bucket (with car de-greaser and then car wash shampoo) and clean away be sure you leave the hood open so the engine air dryes.
You can always try fuel additives to clean out the gunk in your car's engine.
Don't start your car. Get a mechanic to come and take out the gas tank in your car. empty it and clean it out. Also clean out the pipes that go to the tank when you fuel your car. If you have started your car you will have to take out your pistons and clean them and clean all of your fuel pipes.
Synthetic oils will generally keep a car engine cleaner than crude oils would. However, even synthetic engine oil should still be changed regularly to help keep the engine clean.
Plenty of cars can take fuel additives that clean out a good portion of your car and allow for better combustion.
If the engine is blown or if the owner just decides that he would make more money off parts than the actual car
Yes, there are, and they are widely available at major retails. Many people don't like the results, however.
there is water in the engine to cool it down. It is best to use a 50/50 mix of clean water and antifreeze, not just water.
Its possible to clean but much easier to just replace. takes an hour to clean, 10 minutes and 6.50 dollars to replace. better for engine too.
There is a product called Seafoam that can clean out the fuel system. If you don't want to do that you can take it to a shop and have them do it.
Use something like car fax to check on the history of the car. Be sure the engine isn't to clean, that can be a sign they are hising a problem.
Assuming you mean oil pump, changing the engine oil and oil filter on a regular basis with quality motor oil will help keep the internal engine parts as clean as possible.
Clean the battery cables first.