Like the title says. There is what looks to be oil coming from one bolt hole on the exhaust manifold. Ive cleaned the manifold with brake cleaner and let it dry, then started it to let it idle. After idling for about 2 minutes there is a wet spot on cylinder #2. Head was just sent to a machine shop and was cleaned, decked 5 thousands, and pressure checked. It came back with a clean bill of health. Can anyone tell me what might cause this? Here is some pics to help explain this. Im using bolts instead of studs as the head had none. I used the same thread and pitch at the factory stud.

yes i know the bolt is missing, Took it out to see if there might be anything obvious.


This is a pic of one of the other runner. Bone dry.

 

ttt, 200 Reviews and not one reply?

 

Are you sure that is not running down from the head or VC gaskets?

If it is coming out the stud hole, you may have punched a hole/crack into an oil "gallery" if the bolt you used was a little long, what does the end of the bolt that was in that hole look like, any damage to the tread?

Did you check hole depth by placing all the bolts in the holes with out the manifold in place to see what you had for "height" once bolts bottomed out? 94

 

I made sure to use the correct length of bolt. So im sure that isnt it. I did note that over the entire surface of the gasket was a slight film of oil, including the back side of that runner. But the ports in the head didnt have any oil in them. All the bolts look good. I cleaned all the surfaces, Chased the bolt holes with a tap and started my turbo build. So we will have to wait and see.

 

take the header off and see if there is a trail of oil from your valve guide. oil could possibly be leaking through the valve seal and guide.

 

Thats what im hoping isnt happening.

 

Pretty sure if it was a VG/seal the oil would burn long before it could leak out a bolt hole, there is also the gasket, to prevent exhast from leaking past so oil should not get past either. 94

 

OK after further inspection. I think there might have been either trash in the bolt hole or already a crack. Either way, its coming from the back of the bolt hole itself. I bought thread sealant and lathered it on. We will see if this fixes the problem or not.

 

Put a bit of hi-temp RTV around the last 6 threads of the bolt when you you put it back in... If its leaking from the bolt-hole, then that should stop it.

 

Did you find out what it was?

 

Sure its not oil leaking past the valve seal?

 

Cracked bolt hole allowing oil to escape the bolt hole. Usually caused by hydro-lock or a bolt/stud that was ran in too tight. Run the engine without that bolt and see what happens to confirm. You should use studs on your exhaust.

Valve seal leak would go into the exhaust, or did we forget the exhaust manifold had a gasket....