Thanks all for your informative input, I agree that the Radiatior is too small for the job, I had extra tubes fitted to my new one. I still think alloy heads on turbo diesels will have the problems.
I have fitted 2 composite head gaskets and 1 shim metal one in the time I have had tis 300TDi, in the first case the head had warped (380,000klm) 7 thou., I had it machined and the valves reseated.
A few months later the headgasket let go again (in almost the exact same spot on Clyde Mountain on the Kings Hwy.), another composite and new head bolts, the head had warped 7 thou again between cyls. 2 and 3.
On the last occasion I fitted the 3 layer metal gasket, but did not machine the head again. So far (about a year, knock on wood) all seems well, at no stage did the head gasket blow due to overheating, the first sympton of a blown head gasket was pressurising the header tank and later overheating. The warping was in the same position as previously, an area about75mm+ circle covering about half of #2 and #3 combustion areas, so there is a 3 to 4" depression directly in the middle of the head, probably gone soft.
I have worked on and off for around 30 years on mine and others trucks and I have never seen this on a cast iron head, so if I can get a cast iron head for my 300TDi I would be happy, if not I will get a new alloy head a shim metal head gasket and a set of ARP head studs, Regards Frank.

