Having a weep hole is good. Just don't make it too big. Thermostats do not read the temperature of air pockets very good. And this one of the reasons why a motor with a head gasket leak will overheat. The thermostat will not open when there is a air pocket there.
If you have a high performance motor that is on the edge or use nitrous or a tired motor with a head gasket issue having a hole there will help.
The hole shown in the picture is more than enough. I would go smaller as it will affect how long it takes for a motor to warm up.
On a Honda I tried that size it was too big, and the motor never got warm. Tells you how efficient those things are.
Allen
Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first.
Life was a little easier when I was just a wrench.
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