yes they can be over cooled, ie a big radiator and no thermostat...this increases wear particularly on the cam lobes significantly.
A big radiator wont overcool your engine if your using the right thremostat. For an A series i ran a gemini radiator with a 80 degree C Nissan factory thermo, plus I ran an oil cooler as well. Both indicated temps were 80 degrees C and thats where you want to be. No mater what the exernal temp was or how hard i thrashed in in a race 80 degrees and wouldnt nove.

What water temp are people generally running at on their ca18dets? Mine sits almost bang on 80 deg C...

Thanks everyone,
that was a very interesting read. I never had any idea an engine could be over cooled, and damage the possible result.

I always thought a big radiator was better, but it's obviously more complicated. It seems better to use the standard radiator and to stick on some excellent thermo fans so that the temperature never gets too low and when it gets hot, the fans take away the extra heat.

Also interesting that the temperature differential between the rad and the engine should not be more than 5 degrees or so..

Ultimately I need to find out:

if my thermostat is now broken or mismatched to my larger radiator (The radiator might take the temp below it's operating temperature?)

what the actual temperature is (if too low or not)

What the optimal temperature is for the CA18 (I heard it was 90 deg?)

The radiator is from a nissan R32 btw.

justin

Yes, what temperature are people running with CA18DETs?