Did the problem child have an overheating problem before the new water pump was installed?

One possibility is that the new water pump initially caused more coolant to be circulated and over time, junk broke loose from the water jackets and the radiator is now clogged up.

Another problem from the new water pump pumping more coolant to be circulated in the water jackets is that some debris might have broke loose from the head and lodged in the water jackets in the block. To check this out, you can remove the head to gain access to the water jackets and do an inspection. If there's crud in there (especially around the rear two cylinders), loosen the junk with a screwdriver and a coat hanger and vacuum it out. Make sure to check both the head and the block.

Keep us posted on your investigation, what you find, and the final solution. Others will benefit from your experience.

Cheers, Dean

Hello Kevin Ray,

You say that there is almost no water movement at idle, while your 4 door does show movement at idle. You would think that after warm-up there would be movement because the thermostat would be open and the new water pump would show that it is working. After warm-up disconnect top hose to radiator connection and momentarily run engine to determine type of water flow.

I'd say that Rustoholic has you covered with the final solution. But, hows about trying a back flush experiment of the radiator removed and put upside down over a large catch basin to see what comes out. Then, back flush engine before any teardown begins except removing and testing the thermostat and bypassing the heater if you have them. Then go ahead and inspect the baffle plate. Your observations might help to determine if further teardown is needed.  

@harry-truppner 

Already back flushed radiator  its clean same with block clean , no thermostat . Guess it’s time to  pull water pump and see.

If it's an original radiator, it might flush nicely, but be unable to actually cool the coolant anymore. I ran into this problem with my '27 one ton truck (Lurch). I couldn't drive over 25 mph because the motometer would just sail into the danger zone. I lived with this for many years, even after rebuilding the engine, where I know I took a LOT of rusty crud out of the water jackets.

The ultimate fix was to get the radiator re-cored. After that, I could cruise up to 35 without overheating (Lurch has tall gears in his rear end). 😉 I got a three-tube copper regular S-type core put onto the original tanks by a local radiator guy. The cost in 2019 was $750.

Dean

That was my original thought   Untill I saw very little water circulation at ideal or a few rpm. The othe car looks like a river at ideal and runs super cool. Thanks for the information. Hope to take apart after Saturday. I’m going to go ahead and try to get a radiator made just like stock physically the same size. I’m sure with 3 cars I will need it sooner or later. If I don’t use it now. Thanks