I'll bite on a 3 year old thread......didn't think this fella's water pump leaked/squealed either....nor did it pump coolant. Can your mini cam actually view the insides of the tubes or just down the tanks?

 

of course just the tanks..its not that mini...those pics are very persuasive though..thikn this weekend will be a new 2 core and a new pump...thanx for the pic!

 

Just a thought, The cars that ran good w/o a t-stat, maybe the radiators were full of crap thus acting like a restricter plate? Chances are that is why the t-stat was removed in the first place?

 

I thought of that - but in each of the three cases where I ran into it, I'd done a total overhaul of the cooling system (two of the three even had heater cores installed!) so that's not it.

I don't know what it is, and in each case I'd run across an identical vehicle that ran just fine with a thermostat in place, so I finally just chalked it up to "normal variation" and left it alone. I didn't even bother with a flow restrictor plate, didn't think it would have been necessary.