Are 5 cylinder S40 idle more erratic or not so smooth as other make cars of 4/6 cylinders? After fixing a HG, and CV axle the car runs great but I've always felt this car idles strange and not very smooth compared to others. Never owned a Volvo before this car and it always makes a fut,fut,fut sound at idle. The car has no stored codes and it made these sounds even before the Head gasket problem. I'm hoping these short vids although probably hard to tell from them might help someone lead me the right way. Or, maybe it's all just normal. To me this engine almost sounds dieselish. Thanks,

 

I'd check around for an exhaust leak. that can also throw off the mix causing a rougher than normal idle

 

Exhaust indeed a great suggestion, thanks,

 

So, I checked for exhaust leaks which I found none then checked the oil level and found it even below the low hash mark. I asked my son inlaw who does the oil changes for my daughters car and he's only been putting in 4.5 qts all this time. I topped off to top hash mark and now the engine is considerably quieter. Not perfect but better. I'm wondering if all this driving over the years has dried and scoured some of the bearings now. When I went searching of this oil level issue I found there to be some confusion over some dipsticks being of different lengths in various years. Anyways I found in the owners Manual that the correct volume to be 6.1 qts. I just wish my son inlaw would have checked it first 2 years ago.