Castree73

Hi
New to forum and after searching can't find info on my problem so have started post.
I recently got a ml350 with 100000 miles on it, it had a slight knocking/ tapping sound, after I put new plugs and leads on it has got worse.
After googling thought it might be the hydraulic tappets, but I am a DIY mechanic so would really appreciate some advice from someone who knows engines
below is video of engine running

https://youtube.com/shorts/791HraXgR1I?feature=share

Maj. Dundee

I believe W163 vehicles in the UK do not have a CEL (Check Eng. Light), therefore you must own a scanner to read codes in all modules.

Castree73

Thanks for response, in the uk we do have check engine light which is not on and using my code reader (after mk808) it says there are no engine fault codes.

Maj. Dundee

You don't understand, the CEL will never light up because that is the way the UK wanted it to be.

Code reader is obsolete and useless. You need a scanner so it will read codes in all 17 modules.

Castree73

I use a autel mk808 which can read and edit all modules there is no fault code showing , but you can here there is something wrong any idea from the sound? Sounds top of engine under rocker cover

Maj. Dundee

Well then you will have to remove the valve cover on that side and see what is ailing.

Castree73

OK just booked into local garage for next Wednesday, as no point me opening cover unless I know what to look for.
will update post when find out what that sound is

Castree73

Quick update is case anyone is following thread, spoke with someone at work who said check for leads arcing, by opening bonet in dark.
I did and hay presto one of the new ht leads was arcing , change it for one of old leads and now no tapping noise!!
Result garage bill saved and learnt something new.