Coolant flow issue?

my brother has a fresh rebuilt 455 that he can't get the coolant to flow. I'm out of state trying to help. TA Stage 1 heads and a TA high flow pump. I'm thinking he has air in system? he already changed out thermostat. bottom of radiator stays cold. starts and oil pressure is good, any ideas would be greatly appreciated.

 

Just an idea. He changed the thermostat once already, is he sure he didn't put it backwards?

 

i think that is his problem, I just assumed he would do that, but he hasn't put together an engine in over 30 years.

 

I do the same, I figure the system will puke the excess into the overflow if it’s too much.
And yes a helper makes it easier

 

HOW LONG is he allowing it to run? If it's not running long enough to build heat and open the 'stat, of course it "doesn't flow".

Very unlikely to be a problem. Any air in the system gets blown into the radiator the instant the 'stat opens. Then it's seen as "low coolant level".

Thermostat quality has plummeted. Not impossible that he's gotten multiple defective ones...but not likely either.

 

It's so easy to get air out of the system assuming the Stat is good.
If up the system to that cold level mark on the side of the Rad ( that's why the factory put the dam thing there) then run the motor until the Stat opens and pop the Rad cap on just before the filler neck overflows.

 

Have you noticed how none of the thermostat companies, or GM--Ford--Chrysler--AMC--Toyota--ETC., call for bigass permanent holes in the thermostats? Some 'stats come with "jiggle valves" which close as soon as the water pump starts providing pressure.

Drilling thermostats is purely an aftermarket adventure, and almost never needed. About the only time it's actually useful is when the OEM thermostat bypass system is deleted.

Closest I've ever seen is built-into the Robertshaw thermostats--a tiny lil' triangular vent stamped into the body of the 'stat. It doesn't take much to vent air.

 

What is your meaning in saying " bound up" ?
Does this refer to no coolant flow?

 

An eighth-inch hole in the thermostat is not "small". It's fookin' gigantic compared to the Robertshaw solution, which vents air just fine.

And some guys drill multiple holes LARGER than an eighth-inch, even on vehicles with a functional cooling system bypass.

 

I'm having an issue simular. 195 t-stat with 2 small holes top and bottom. It seems to overheat but is actually cool to the touch on rad cap. Temp shoots to 250 then when I punch it it cools down fast. Is that an indication of a bad waterpump? It's like it's not flowing until the engine revs up.

 

Could be any one, or a combination of several problems.

In no particular order:

DOES THE FAN CLUTCH WORK PROPERLY???
Radiator air-fins plugged with dirt, debris, butterflies, sparrows?
Radiator air-fins corroded so they aren't touching the water tubes?
Verify water pump pulley ratio
Verify spark advance including vacuum advance. Retarded timing--including lack of vacuum advance--causes excess heat rejection to the cylinder head.
Assure water pump is in good condition--which probably means removing it and actually looking at the impeller and the impeller clearance.
Check fuel/air ratio when it's running hot. Lean fuel/air mix burns hotter, standing on the gas causes enrichment via the power valve/power piston.

 

Thanks to your advice I now pop one of the temp sensors (I have the two -gauge and light). It makes the fill simple and avoids fussing around with air pockets. Takes two secs.