A bad engine knocking sound started this morning on a very cold start and got much less pronounced on warmup but you can still hear it slightly after warm. It never made any noise until today so I don't think it could be piston slap - ??, although it sounds like what has been described as piston slap to me. It almost sounds like it's coming from the exhaust manifold but a sudden leak there doesn't sound likely. It was also accompanied by very poor perfomance - it almost would not run or accelerate at all until I pulled over and let it warm up. After warmup the poor performance part went away but the knock (deeper than a valve train tapping I think) goes on. Plan to just check the valve clearances and pucks when I get home just in case but it really doesn't sound like that. Any other input greatly appreciate. It's the kind of sound that in my past non-Volvo cars I have had meant impending doom.
Robb