Must be a great price. Here's what I would do if I had to have it. First, take it to either your mechanic if he's familiar with Volvo or to an independent Volvo shop or a dealer for evaluation.

You sound pretty sure it's coming from the top end. If you remove the oil filler cap is it sharper sounding? I'm just guessing and have never heard of this happening in a Volvo, but it could be a broken camshaft lobe. I've had a welded up camshaft come apart before but that was a different application altogether.

If I recall, bad rod big end bearings will protest under load, crankshaft main bearing under trailing throttle, or light load. What does the oil look like?

They again, could be a frayed timing belt slapping around under the cover. Or a bad exhaust manifold gasket will make more of a "snap" than a "knock." I had one blow out at higher revs recently.

Just guessing, good luck,
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Erwin in Memphis, '88 745t 183,000 miles, '95 855t For Sale