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Originally Posted by Michael1
I don't know about modern trucks, but in the old days (70's, early 80's), there were some clutched fans on GM's Heavy Duty Cooling Systems that would drop radiator temperature even at 60-65 mph. It sounded like a jet engine when it engaged, and I believe it took about 10 hp to run. That might be a bit much for the little H3 engine.  I think the aerodynamics are better on today's vehicles with respect to cooling system air flow, so such "big mutha" fans aren't needed.
Do all of the dealers have "vac-and-fill" systems now?
It can be a real bear getting some cooling systems voided of air, and it definitely can cause overheating. Some GM vehicles have air bleed valves which help some.
Michael |
The H3 has a large grille opening for air flow, max airflow through the radiator will be forced it at speeds. Now on the C5 Vettes with no openings in the front for airflow, just the lower air flow deflector, fans will turn on at speeds to help draw air through the radiator.
GM recommends Vac-and-fill for all vehicles now, but not a requirement; yet.