Exhaust manifold leak

[JMBT]

   Hey guys here’s what I have got. CM2250, @m*m^2, 645K, oil or soot, or both coming from 2nd cylinder exhaust port leaking past the manifold gasket. Truck is running great, fuel mileage good, power good, but manifold temps are a bit higher than normal. Cylinder cut out test, runs on all cylinders individually, but sounds equally crappy on each, so I am guessing normal for the age of the motor.
Could the oil be from failing valve guide seals? Truck also smokes a bit after I have idled to warm up in the morning. Then quits until cooled off again.
Brother and I replaced the manifold and gaskets 160K ago, but before the truck was demandated. Since deman the exhaust temps have been higher in hard pulls. Could the manifold have shrunk?? I have heard of that happening before, however none of the bolts look bent.

[Starlight]

Heres what i see quite alot. The centre section of the manifold distorts with age resulting in leaks either on the number 2 or 5 positions. Not certain that'll be the case with yours but def something to closely look at when you remove it. Probably oil leaking past valve guide seals that your seeing

[JMBT]

The for the reply Starlight, do you think it would have distorted in 160k miles?? If it did distort, am I looking at another new manifold or just new gaskets, bolts, and retorque?? The upside, if there is one, Once I get the manifold off I will finally get to put an eye on the exhaust ports to determine if the valve guide seals a bad. Have been thinking that for awhile, but work has been fairly good so I haven’t came off the road to pull it all apart yet. Looks like the time is now! One more load to deliver than we will break her down.

[Starlight]

Ive seen even less miles than that do it. Put a straight edge on it and check it with a feeler gauge. There's also the chance that you just need to fix the oil leak and install new gaskets. Manifold might be perfectly fine

[JMBT]

Thanks again! It will be a few days before I get to tear into it, but I’ll post what I find.

[Rawze]

My number-5 got slight dark patches around the outside of the manifold gasket about 3 weeks after my inframe. It never got bad enough to worry about and has not made any large black areas indicating anything more than a micro-seepage around the gasket to justify replacing it again.

[JMBT]

Rawze, was it the same or less then my picture above? I cleaned it up the best I could yesterday, just to see how bad it leaks going across the country on this next load.