The nuts I'm talking about are the three that hold the exhaust pipe to the exhaust manifold.
I have tried double nutting each one, in an attempt to jam the nuts together. I have tried high temperature Loctite on the threads after cleaning them. I have even tried lock washers.
Nothing helps. After only about three or four days, the nuts have loosened and there is an exhaust leak.
I wait until the engine is stone cold, then tighten the nuts. After the engine has gone through another heat/cool cycle, I'll recheck the nuts.
The gasket is, or was, new when this problem first started a couple of months ago. I replaced the gasket after the nuts all came off.
What next? This problem is driving me nuts. (I know, really bad pun)

Thanks.