That time a 6.7 Powerstroke injector cup cracked on a highway pull

I was doing a hot tune test on a customer's truck near Flagstaff when it started dumping coolant into the oil pan. We pulled over, and I had to pull the head right there in a parking lot with a basic socket set and a borrowed torque wrench. Has anyone found a better sealant than the standard anaerobic stuff for those aluminum cups in high heat situations?

2 comments

2 Comments

holly_young351mo ago

Been there... had a cup let go on a tow rig under load. The factory stuff is fine for stock, but for tuned trucks seeing real heat, we switched to Permatex 51813. It's a high-temp anaerobic flange sealant. Clean the bore with a brake hone until it's shiny, heat the cup with a torch before you press it in, and let it cure for a full 24 hours. Haven't had one come back since we started doing that.

noah1351mo ago

Saw a tech bulletin from a diesel shop in Texas that swears by Loctite 518 for aluminum cups in high-heat apps, same as holly_young35 said. They stress getting the bore totally clean and dry, no coolant residue at all, before applying. Letting it cure with the cooling system empty and pressurized seems to be the real key.