cooling systems on a car

regarding to my knowledge modern diesel engine has:
*engine radiator,
*ac cooler and
*intercooler
located in the bumper. The first (regarding to the air stream) is intercooler, than AC cooler and finaly the radiator.

Intercooler is somethimes located under the hood(bonnet), like with imprezas, or in one of the side of the bumper, like with VAGs.


Apart of these main liquid to gas heat exchanger, there are also:
*engine oil cooler (only some aluminium ribs attached to the sump(carter)),
*EGR cooler (where gas is cooled with engine water running throw EGR cooler),
*hydraulic oil cooler (also only a couple of ribs or curved pipes)
*fuel (diesel) cooler.
I gues that turbocharger bearings are attached to the engine oil system, so they are also cooled with same oil and same oil cooler.

Hope I didn't miss any of it (for an ordinary stock engine withought automatic transmission, not race ones, that also have brake oil cooler and even shock absorber cooler)

So if anywhone can explain why do need to have all of these coolers (fuel, oil cooler), and if gas engine has them too.

The quick answer is that internal combustion engines are very inefficient --- meaning there is lots of waste heat from the fuel you burn. The more fuel you try to burn to get the power you want means more potentially harmful waste heat that you have to get rid of effectivly. Each automaker tests and decides where heat could be harmful and installs devices to try to control it-- get rid of it quickly without harming the car so its life is prolonged.

The quick answer is that internal combustion engines are very inefficient --- meaning there is lots of waste heat from the fuel you burn. The more fuel you try to burn to get the power you want means more potentially harmful waste heat that you have to get rid of effectivly. Each automaker tests and decides where heat could be harmful and installs devices to try to control it-- get rid of it quickly without harming the car so its life is prolonged.

This is really indeed an technical answer, but only if the answer will be posted by a child and will be like: "why do engines need coolers?"

As you can read I am not asking so generally and I know that coolers are there to transfer excess haet to ambient air or other medium.

What I am asking is to why you need oil and fuel cooler, and if you needed onyl on diesels or even on gasoline engines.

And let me answer to a part of my own question:
oil cooler is to warm the oil at the cold engine start (to reach the optimum lubrication as fast as posible) and to lower its temperature durring full engine load (to keep the optimun lubrication)

As for the fuel cooler, I have read so far:
Fuel cooler is mainly on diesel direct injection engines, because fuel gets quiet warm when passing through high pressure fuel pump and because exces of it flows back to the fuel tank it has to be cooled.

Easy there sparkplug :)

Fuel coolers are mostly optional. Cooler fuel makes a bit more power (more on gas than diesel) but more importantly cooler fuel can make the difference between passing NOx emissions standards and not. Its a $20 part that the manufacturer feels will be better than having 300,000 customers complain when their vehicle fails an emissions test.

You need an oil cooler especially on a turbo diesel. Turbos since they run off exhaust gasses can reach screaming hot temperatures; 1200 degrees or more. Oil is healthiest between about 200 and 230 degrees farenheit. Without a cooler, the extra heat load placed on the oil would cook it.

For the most part, its not a diesel or gas thing, its an engine design thing. I have a non-turbo diesel that doesn't have an oil cooler. Diesels are typically a little more thermally stable, so the oil stays cool since there is no turbo. I also have a gas police car that they added an oil cooler to be safe on a vehicle that sees a lot of abuse.

Also regarding oil coolers.
Many turbo diesels have oil squirters aimed at the underside of each piston, while these are very effective at cooling the pistons, that heat goes into the oil.

My turbo diesel has an oil cooler right down the side of the block. It is cooled by engine coolant and I guess has a secondary benefit of warming the oil in cold climates too.
If I run it hard up something like a ski-field road (gaining 1500m in about 15km) then at the top the oil is hot and thin enough that the oil pressure drops at idle and the light comes on.

Easy there sparkplug :)
I am icy cool.:grinyes:
Fuel coolers are mostly optional. Cooler fuel makes a bit more power (more on gas than diesel) but more importantly cooler fuel can make the difference between passing NOx emissions standards and not.
Well I can't agree you on that. Today I talk to my audi suplier (technical section) and a referee told me that on the VAG's car only diesels have fuel cooler and it is attached at the return fuel line, so on the low pressure line. Its main purpose is to lower fuel heat because fuel tanks are made from plastic, that is not verified (by TÜV) for the temp above 70 deg C.

I am icy cool.:grinyes:

Well I can't agree you on that. Today I talk to my audi suplier (technical section) and a referee told me that on the VAG's car only diesels have fuel cooler and it is attached at the return fuel line, so on the low pressure line. Its main purpose is to lower fuel heat because fuel tanks are made from plastic, that is not verified (by TÜV) for the temp above 70 deg C.

This is undoubtedly true. But Curtis' comments regarding fuel temperature and emissions are equally true. I know landrovers TD5 engine had systems to closely regulate fuel temperature into the engine. This is seperate to the need for cooling fuel returned to the tank.