Diesel cooling system
 

Do our diesel cooling systems REALLY need an expansion tank?
would things operate just fine with a radiator with a cap?

I have a chance to get a really cheap custom aluminum radiator and losing the expansion tank would really clean things up in my engine compartment...

No, they don't need the expansion tank as long as the radiator cap and water level is high enough.

Any ideas why there is an expansion tank?

More water capacity, no liquid loss out the cap when pressure is vented.

Makes sense.

So then if I got an aluminum rad of the same dimensions with a cap top center that should be alright?

I don't see how it could hurt. I know one member is running his 617a 4-speed conversion with the stock 240D radiator.