Aside from wasted money, can you have too big a radiator?

I'm guessing probably so ... if the flow can't be metered with a thermostat.

Why do truckers in cold climates put canvas over the radiator -- do they not have a thermostat or is the air flow over the engine sufficient for cooling?

Although the thermostat closes off coolant flow the air moving across the radiator does cool it.

In 20 below weather I cannot get heat out of my benz diesels unless I cover a bunch of the rad.

Too big a rad just wastes money. It may cause other issues as well.

__________________
[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.

Cold air in the intake & high efficiency motor will make low operating temps. They have a thermostat, it just doesnt open.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving