I have had this chronic ping on my 1980 245 for quite some time, and it is driving me crazy. I've tried higher octane fuel, replaced the oxygen sensor, and had the timing in about every position possible (currently at about 6-7 degrees). The ping is obviously bad under acceleration, but it's also bad just sitting and idling, so much so that you can clearly hear the clicking inside the car. Under the hood, I can hear the click most prominently under the valve cover right at cylinder 4. Could I have a bigger problem than normal knock a lot of people struggle with on this board? I haven't really noticed a loss in power or diminished fuel economy, and the head was remachined and a new head gasket put on a year ago. I can't seem to find any other problems with the car, save this blasted pinging. What else can I do to help fix or diagnose this problem? Thanks!

Jason

I seem to recall there being valve noise suppressors included in the valve seal kit I bought when I did my head gasket. The shop that did the valve job was familiar with Volvo heads and knew what to do with these - sounds like your valves for cylinder #4 may be missing them.

Zack
1980 245DL M46 274k
1985 744TD M46 250k
1988 745T+ M46 200k

Jason;
Detonation/Ping/spark knock/ is definitly a concern, though you should have been able to affect the condition through adjustments in octane & timing.
Look to a valve adjustment and cam flotation for possible "click" type of noise

or an exhaust leak
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80 262C Coupe- (FSO black, M46, original) 82 244GLT- (auto)