Brian,

I may be missing the point, but your SD does not sound as if it is controlling temp appropriately. While I can understand some increase in temp under heavy load, with appropriate air flow at speed the transfer should offset the increased heat load.

Something isn't right ... or, am I missing the point?

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

Well, it has a brand new water pump, a brand new thermostat, it behaves in an identical manner whether the ambient temp is 0F. or 95F...........so, if it's not behaving properly, I'm willing to listen to all rational ideas..........

You can't condemn the radiator if the performance is identical at 0F. It's the only item in the system that is "aged".

Hmmm - was the temp maintained in the same manner prior to all the replacements? Prior to the new tstat?

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

It was absolutely identical with the old stat.

However, it has changed behavior over the course of the last eight months or so. Previously, it would very rarely climb above 90C. The ambient would have to be very high. Now, it climbs to 95C. just about every day..........

i would suspect your rad.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

If the rad was marginal, it wouldn't hold 95C. at 98F. ambients.

The fact that the performance is identical, independent of the ambient temp. would effectively rule out the rad.........don't you think??