Originally posted by esterix@Jan 5 2006, 01:31 PM
One of the main reasons for the move to water-cooled engines is noise emissions. Stringent type approval laws simply make it more and more difficult to pass. Water in the cooling jacket absorbs sound. Without it, you get the characteristic sound of a sewing machine embedded in the motor. Exhaust emissions is another since with a water-cooled system, you have better control over emissions
Contrary to believe on oil leak issues, it is widely regarded as acceptable to have the odd weep or two of oil in air-cooled Porsches and VWs. The solution for the older cars is simply a gasket change - no engine rebuild required. In fact, if the motor has been regularly serviced, no rebuild is required for well over 100,000 miles. I have even read of a 911 having covered 450,000 miles without a rebuild! However, for cars which are not as well looked after, you may need a top end rebuild involving valve guides and such, but you talking about the same time/mileage as your average BMW water-cooled engine anyway.