Finished Complete rebuild of D16A6. .040 over bore, 10.5 compression, new internals-block & head---clean. The block had been used in my SCCA race car just fine. After completing instal in street car I started losing coolant 1 liters per week. But no visual loss. Then I see a wet spot between driver side motor mount and water pump, Fluid leaking down onto timing belt tensioner. Replaced water pump. Stil lleaking. Finally pulled off driver side motor mount and ran engine. It appears that coolant is weeping from a invisible crack in block under motor mount 1 drop every 2-3 seconds. Has anyone ever heard of this issue and besides JB weld what are you using to repair this external leak. I know the proper way is to remove engine and weld, but after completing a two year complete restoration I'm tired...

 

the water pump has a weep hole designed in it. if the pully seal goes, itll leak and is more of a warning of imminent overheating. this would be the likely cause.

but you said you replaced your water pump already, hopefully with a new one. assuming you did it properly and the gasket is properly sealed, then i cant think of anything else other than a crack.

 

I know about the weep hole on the side of the pump. This "leak" appears to be coming from under the motor mount casting, solid metal. Like i said when the mount is off, car running and you use a mechanics mirror you can see the water appear out of the block under pressure. But no visible crack or hole. I was just looking to see if anyone has had a similar problem, and what viable filling options to fix this leak besides JB weld or welding that requires engine removal.