For what it's worth, my drain plug really didn't flow back in to the coolant passages well either.  I don't think the connection to the main passages is very big.  I used compressed air and it was prettty well plugged.  But the block itself flowed fine.

Still though, the path from T-stat hole to pump should be clear, and the pump is not a positive displacement, you could call it an inertia pump, it just creates a pressure differential by pushing coolant.  Like a turbo.

If you do remove the pump, then the passage from T-stat hole to block inlet/pump outlet will be even more clear.  You could put your ear on one and hear somebody talking at the other end.

If the holes at the top of the block were clear, and the head gasket is right, it really seems like there must be something in that pump outlet area.  Found a picture of coolant draining, and a video.  I think he's a member.  Koenig sounds familiar.  Good luck.

 

I believe I found the problem!

The outlet passage on the w/p was completely plugged up with a yellow/green substance,  I'm assuming dirt/rust mixed with anti freeze.

Poked at it with a screw driver and a whole bunch of very brown water came out, finished cleaning with a stubby round brush.

Time to put er back together.

That is it, problem is solved.

took it for a drive and the temp refused to even reach half, let it idle for an extended period and the temp stays at half solid  (its a sunny 70 degree day)

time to drain, flush reinstall thermostat a/f and heater hoses. then continue to finishing the a/c.

I been working on cars for over 30 years (about 10 of that professionally) never seen anything like it , couldn't even imagine that it could happen. 

To future generations: if your car overheats and acts as if the thermostat is not opening WITHOUT a thermostat check the water pump passages for blockage.

Good find...

More like dumb luck, I would never have thought to look for it...."antifreeze pertification", phrase coined.

On 1/29/2018 at 8:54 PM, Zed Head said:

If the holes at the top of the block were clear, and the head gasket is right, it really seems like there must be something in that pump outlet area.  Found a picture of coolant draining, and a video.  I think he's a member.  Koenig sounds familiar.  Good luck.

 

Am I being trolled?  Just can't tell...

28 minutes ago, Zed Head said:

Am I being trolled?  Just can't tell...

Care to clarify? sorry, I don't  understand your question.

The hole I pointed at with the red line is the outlet.  Maybe you meant the inlet?

 

The big round hole in the center is the inlet and it was free and clear, the outlet is on the bottom left of the pump,(looking at it from the front). it's not very big, about 3/4  of an inch in diameter.

It's the opposite. The coolant is pushed through that hole in to the block, where it flows up and to the head.  The hole on the left of the pump is the inlet, from the front cover passage.  The back of the pump is all outlet, pressuring that big hole with the passage in to the block.

All clear now.  Thought I was missing something.  Carry on...

I'm sorry but that is incorrect, very based on my experience today shoving the garden hose into different orifices  (get your mind out of the gutter)watching for flow.

when the hose is spraying in the lower hose water comes out from the center , when its sprayed in the upper hose it comes out from the bottom left (the one that was clogged). of course the 2 are bypassed by the heater hoses and the manifold that feeds back to the thermostat housing.and it can get a bit confusing.

Think turbo, the inlet is in the center, outlet is on the side.

Alright.  Must be the passages in the cover that confused me.  I'll stand corrected.  Until I know better.  Something to explore...

So you did use a garden hose...