[WMX267]

I noticed that it still happens even with the blower / heater off, but it's not really that noticeable - I'm figuring it might be from the temperature outside lowering the coolant too much before it enters the engine again, plus, it's not accompanied by the thumping sound. BTW, the collapsing of the upper radiator hose has stopped, but there's still the thumping - sounds like it's coming from below the engine compartment. Basically, with the heater off, it doesn't go all the way down.

I checked the fan clutch and it seemed okay to me. Vehicle off and cold, it doesn't rotate freely, but it is movable by hand with the limited amount of space. It would barely make it 1 1/2 a turn though. Should it be more free? I could have overtightened the big bolt to the h20 pump when I replaced the h20 pump. Could this be the problem or matter?

Anyway, after starting the engine, it (the fan) starts to engage immediately and after shutting the engine off, it would rotate a good 1-2 seconds before stopping. Does this look fine?

I haven't checked the sending unit thinking that it doesn't explain the thumping noise. A faulty thermostat could not be it as well since it's new, it opens and closes and coolant circulates.

I'm lost here. I hope somebody can bring up more ideas, or a more systematic approach to diagnosing. Thank you very much.