extremely loud tapping noise from top of motor

[PeteV40]

Hi, my 2000 V40 with 202,000km has just developed a very loud ear piercing tapping noise which I think is coming from top of motor. Initially I thought it was a blown exhaust gasket near manifold but suspect it may be a valve or lifter. It recently had a service 60kms ago with fully synthetic oil, new plugs and oil filter. To be more specific the noise now sounds like a diesel motor ticking over (but on steroids), and as the revs go up, so does noise to the point were you do not want your ears near the engine!! Could it be lifters, valves, o-ring, pcv issues, or anything else? Experienced heads replying would be appreciated. Thanks.Pete.

[MadeInJapan]

Whatever it is, this does not sound good and it could be major engine issues, or as you say, it could be sticking lifter. You might try a compression tests...are there any fault codes set (check engine light). I have also heard some success for unsticking lifters by doing a Seafoam treatment by sucking in 1/3 of a can into a vacuum hose and allowing the fluid to kill your car, and then letting your car sit for 15-20 minutes and before starting your car and burning all of the Seafoam out. If you decide to do this treatment, please read up on it in this forum as it is controversial and some claim it can do more harm than good.
My experience with Seafoam however had been very good and I tned to do a treatment at least once a year (sometimes more) on my S70 and my son's 850.