Epoxy for Block Pinhole
 

What is the best epoxy to repair several pinholes in an old IA2 block? It had a crack between the freeze plugs that had been welded and there was some porosity. When we put the engine together 3 years ago it was epoxied b the machine shop and overtime it started to seap coolant. Our header was almost touching the block in that area broke down the exopy overtime I think. We have modified our headers to get about 3/4" clearance to that area now so hopefully that helps. Thanks

splash zone is the best found.

splash zone is the besti found.

Moroso 907 will stand up to far more heat then splashzone, and if you want to go a step above that then get some ciramic Aluminum epoxy from Coltronics ny.
The stuff is not cheap though!

Belzona

Yup, Belzona would serve well also.

I used Coltronic ceramic power on my Exhaust Crossovers and it was fine. Not sure about sealing coolant pinholes.

Epoxy solutions just seem "better" if they are known to survive ethyln glycol. I used JB-Weld on a radiator gouge from the mech fan and the few rows stayed sealed for a decade until car sold. Probably better epoxies out there for cast-iron adhesion.

Hysol ... EA9394 ... can be bought in small plastic pouch... good to 350° and more

Loc Tite is actually better than epoxy for sealing pin holes because it's thinner and it can flow into the casting. The correct way to do it is to put it in an autoclave and while under vacuum and pressure it will draw the loctite into the casting. Of course most of us do not have access to an autoclave. If you can use pressure to get the loctite into the casting that should work. Of course I would use red loctite. Whether you use loctite or epoxy you need to draw it into the casting and not just on the surface.