oil leak from head gasket area

[ChrisDixon]

Having chased down some leaks from the cam cover gaskets I thought I'd got them all but as we've got into winter I now have one that manifests itself when the engine cools down. It seems to be coming from the exhaust side of the head gasket between cylinders 1 and 2, runs down the side of the block around the drain plug (I think there should be a tap there) and collects on the flange of the sump near the bellhousing. I believe the head gasket was changed and the car little used since. One concern is long stud corrosion, another an inferior gasket, but I thought I'd start by retourquing the head. Do I slacken the nuts first, and maybe remove them and inspect the visible parts of the threads, and lubricate them a little, or is that a bad thing to do? If the right thing to do is pull the head and inspect things more closely I can do that. But there are no signs of oil and coolant mixing so I'm not looking to strip down just for the sake of it. On these engines is it possible for the domed nuts to run out of thread (i.e the stud hits the crown of the nut) for any reason?

A related question, what happens if the studs have rusted where they pass through the water jacket? Is this how the so called "stepped" block problem can occur, and how concerned should I be about the possibility?

[mike020150]

Hi Chris,
It's always best to start with the easy stuff before fearing the worst. It's much more likely that the car has either a leaking cam cover or timing chest gasket than anything more serious. Why not first carry out either a compression test or a leak test in order to rule out a head gasket which is leaking where it matters? It's not the best of ideas to release head nuts without intending to remove a head. If you have concerns that the head hasn't been torqued correctly, simply tighten any loose nuts without backing them off. Mike.

[ChrisDixon]

Hi Mike, yes maybe I have got long stud paranoia, and I had thought about a compression test. But I've got some new improved cam cover gaskets and new O rings so I might as well fit them and see if that makes a difference. I've already replaced the oil feed pipe washers. Maybe I'm not seeing a leak when hot because its burning off being so close to the exhaust, although I can't smell burning oil. At least on an XJ6 you can see what's going on better than I could on my S Type!

[3.8etypephil]

As Mike wrote, don't slacken the head nuts before re-torquing, and never lubricate them as the torque settings are calculated dry.
The only time that I have ever encountered the domed nut bottoming out was when stripping a previously "specialist rebuilt engine", which had one of the longer studs designated for the engine lifting eyes fitted to an inappropriate position after said "specialist rebuild". Your oil leak almost certainly emanates from the cam cover area, so consider that your Christmas present.