420sel89

Hello, i have a 1989 420sel. Has ticking noise on the passenger side when engine is on, so i’ve de To take off the valve cover piece andfound out one of the valves on the exhaust side is a little loose. If I adjust it, will it fix the problem? Or does it need to be replaced?
Also if anyone knows what is the feeler size to adjust is? And where i can find the adjustment tool?
Thank you

dikdaan

Try posting on W126 section.