When i pulled my engine & transmission, i found some damage on the firewall. Probably from the last time the engine and trans was removed. It’s not visible when everything is installed.

What’s the easiest way to patch this up?

 

Find an old piece of fiberglass boat to practice on is the best way, if not practice on a piece of cardboard tacked to the garage wall. except for the grinding

grind it out smooth with a flap wheel so that it can be filled with a piece of fiberglass mat. Any cracks should be ground out slightly with a feathered wedge along the crack. Where it ends drill a small hole at the end so the crack ends at the hole and it will not continue. Cut the mat to fill the prepped area. lay it on a piece of plastic or buy so release film and lay it out on a table with a big piece of cardboard as protection for the table. Lay the release film on the cardboard big enough to go past the area you are going to repair. mix enough fiberglass to cover the mat and the fire wall lightly. Cover the mat with fiberglass resin dabbing it onto the mat with a 2 inch wide cheap brush with the bristles cut short to about an inch. Peel the mat off the release paper and flip it over and cover the other side. Use a second piece of release film to squeegy the majority of the resin out. Peel it off and put it on a clean third piece of release film. Put a light coat of the same resin on the fire wall going about an inch past the area that the mat will cover. Once the fiberglass starts to get tacky push the mat and release film onto the fire wall and squeegy it into the area leaving the release film intact over the mat smoothing it out onto the firewall. Leave the film on the mat until it dries. Once dry peel it off and sand to suit the wall.


the release film makes fiberglassing pretty simple but practice first. If you can find an old boat in a junk yard you can cut a good ***** out of it to practice on