exhaust studs leaking oil on em6 300

[puppydog1918]

Just had recent engine work done to em6 engine. i just had the heads rebuilt from mack and since rebuild oil is leaking from the exhaust studs

wtf. anyone know why or how before we rip it apart again?

[Kyle 537]

Usually Valve seals. Maybe rings but I'm guessing no power issues. Maybe they damaged a seal.

[wheeler73]

Is it the lower exhaust studs? If so you can take them out and clean the holes and studs and appliy silicone to them and reinstall them and see if it stops. The Mack grey silicone works the best.

[midnitebluess]

If the oil is leaking from the lower studs and not around the manifold gaskets. then the last post is correct. the lower studs in the head are drilled through to the push rods. the manual refers to installing the lower studs only so far into the head. if installed to far into the head , the studs will actually rub against the push rods. I had just finished a E7 mack engine rebuild and use the Mack elastic Grey silicone on the lower studs. I don't have in front of me the actual measurement for stud depth. safely can say that the new studs have red lock tite on them. you can install studs until last thread of lock tite is seen. you only need alittle silicone on threads.