W124 300D temp skyrockets within 2 blocks

[dancenplanet]

I have a W124 1993 300D 2.5 turbo. I just replaced the water outlet ... thing, because it had developed a hole and was leaking coolant everywhere. The repair was a success ... sort of. I refilled the coolant reservoir and took for a test drive. There is no more leak, but the temperature shoots up to 110 within just a couple of blocks. My coolant was green, now its water, but thanks to this forum, I plan to de-oil, flush with water, acid flush, remove block plug, water flush x5, and add the MB coolant. But before I do that I'm wondering if there is a way to test the water pump. It seems to me, unless the cooling system is full of sludge, which it doesn't seem to be since water flows through it clearly, it seems to me I should be able to go more than a couple blocks before over heating provided the water pump is working. When I drove it I ran the defrost to try to get water through the heater core. But even though the temp was off the charts, the defrost was still cold. Is it possible that the leak (and running dangerously low on coolant) caused damage to the water pump? How can I test it?

Thanks
Chip