Cam Tower Leak or Cam Seal Leak?

[mca]

18k on rebuild - nearly 4 years ago. Engine is still clean and fresh.

However, I recently got a whiff of burning oil and noticed that oil was dripping onto the passenger header toward the front of the engine (near the mounting point with the muffler). Oil is running down the heater hose - the one that runs from the fan outlet on top of the engine to the SSI.

For the life of me I can't determine the source. Tonight I removed the header and tried to get a better look. I'm convinced that it is either a leak at the cam tower or the cam seal. No leak from valve gaskets, no leaks from chain fed lines, no leak from on top of the engine, etc.

About 3k miles ago I torqued my head studs while I was doing a valve adjust (figured it needed to be done) - a few were looser than spec. I'm thinking that I might need to go through the cam tower nuts in the pattern specified in the 101 engine rebuild book and do the same thing.

Would this be a waste of my time or is it possible that it would stop the leak?

Is the cam seal a likely culprit - more likely than the cam tower?

What would you guys do?

Thanks,
Craig

[Scott R]

This may be simple thinking, but did you check the crush washer on the oil line restrictor coming off the cam housing? I had a leak from there and it dripped down the heater hose as well.

[mca]

I suppose there is also the possibility that it is a leaking rocker shaft on the intake side.

Guess I'll go ahead and open up the covers.

[mca]

Originally Posted by Scott R

This may be simple thinking, but did you check the crush washer on the oil line restrictor coming off the cam housing? I had a leak from there and it dripped down the heater hose as well.

Ya. I replaced that one about 6 months ago. You are correct - when it leaked it looked identical to what I'm seeing now. Unfortunately it is bone dry.

I just drained the oil and opened up the lower valve cover. No rocker movement or leaks. It dawned on me that some of the cam tower nuts are behind the rockers so I won't be able to tighten those. I checked the accessible nuts and they were all at 25NM.

I'll do the intake side tomorrow.

With the lower valve cover off I was able to get a much better look at the cam seal. I looks like it is the culprit. I could see where oil had spread from the bottom of the seal.

There is still a chance that there is a rocker leak above - slim chance but worth the investigating since I've gone this far.

Is the cam seal a high pressure area? If I recall, I only used Curil-T on it during the rebuild. Man it would suck to have to replace that thing!