When engine is idling before and after it has warmed up I hear a knocking or ticking sound coming from engine. It use to be when I heard this sound I just needed to top off the engine oil to elininate sound, not any more. I have read somewhere on this site it may be due to some o-rings? to some pipe that deliver oil to the top of the engine? Anyone know how to locate and check these o-rings and what is involved to fix if this is indeed the problem?

Brian,
Could this ticking be coming from the hydraulic lifters? Does it increase/decrease with rpm? Is it coming from the heat shields? Does it do it at 2000 rpm? Are you using synthetic oils? How many miles and what year is you car?
Klaus
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98 V70Rawd(101Kmi), 95 854T(85K mi), 88 245(165K mi)

No itis not heat shield rattling. It sounds like lifters and ticks faster with increased rpm. Drive down the road it usually goes away. I use synthetic blend oil and change every 5k

The o-rings you are asking about are inside the oil pan.They seal off the oil pick up lines.The fix is very involved as you have to suspend the engine/transmission assy,lower the subframe and remove the oil pan.It is not something the average weekend do it yourselfer would want to tackle.Really the only way to check for this is to use a oil pressure gauge that threads into the intermediate section of the block where the oil pressure switch goes and read the pressure values when the engine is running.

Would it be a good idea to install a oil pressure gauge in the dashboard just to make sure the engine is not damaged by low oil pressure?
What kind of pressure can you expected on a healthy engine compared to one with faulty o-rings..?
Can the o-ring problem appear also on engines of year 2000 and later? Since those do not have hydraulic lifters, I guess there will be no valve noise?

rgds
Erik