Head leak

[Dodgerdallas]

Theres coolant leaking from the front lower exaust nut on the front of my 66 318 poly after its been sitting and cools off,somebody said it might be the stud that goes into the water jacket that didnt get any sealer on it,if I remove the exaust will I be able to tell if its the stud or a crack???

[Fred]

 You'll be able to tell for sure where the leak is coming from by removing the exhaust. My guess would be, it's coming from the stud.

[Dodgerdallas]

Ill look and see-thank you sir...

[Dino]

There's going to be a lot of coolant coming out when you remove that stud so have a basin in place.  I do think it's safe to assume it's the stud so you could drain some of the coolant first, remove the bolt (replace if needed), add some ultra copper and let it sit overnight.  Next day fill 'er up, drive it for a bit and retorque the bolt.  If it still leaks, it ain't the stud...

[Dodgerdallas]

What is ultra copper and how do u use it?

[Dino]

What is ultra copper and how do u use it?

Permatex ultra copper rtv silicone.  Available at any auto parts store and most diy stores.  It's a tube of orange high temp silicone.  Put a small amount on the stud and screw it onto the block.  It'll set up quick and form a flexible barrier.  I did mine last summer and not a leak anywhere.

Use the same stuff on intake manifold gaskets and valley pan.

[MSRacing89]

The stud could be partially stripped and causing the leak.  You may need to heli coil the thing and insert a new stud.