help, help.....my 420 V8 ticks !! I'm thinking hydraulic tappets but where are they??, can they be replaced without removing the head?, does the cam need to be removed before I can get at them, I am ashamed to drive it cos of the ticketty ticketty. Serious for a moment tho, it sounds like just one is sticking, any advice?

have the same ticking
 

I have the same ticking on my 94 s500 i think you just have
to remove the valve covers maybe someone here could give us
more information on the procedure i was told that it could be a broken or out of place oil tube or bridge

ticking (W126)
 

I have the same problem as well on my 560 SEL...

I posted a msg. a month ago and came to the conclusion (Thanks to John Sullivan :) ) that the rocker arms need to replaced. There is a process for this in the Mercedes CD manual. I'll attempt this job sometime this summer.

If you do a search for "ticking", my msg. and it's replies should come up.

On the 420/560 motor it is most likely that the problem is a rocker arm to cam issue. It can all be done without removing the head. Removing the rocker arms to view their surface would be the first step after removing the valve cover. The removal is facilitated by the special spring depressing tool.

There will be no way to see the bad part of the rocker without removal. If the cam is rough you won't need to remove them for a diagnosis but it will require a cam. MB says that cams and rockers should be done together. In the field the rockers are replaced without the cam, at least till the cam is rough.

Be sure the cam oil tubes are tightly mounted into the cam stands.

Impressed by response
 

thanks for the speedy info, am trying to trace this elusive CD you all love so much :) and then those hydraulic thingys are getting a crash course in computing so they can read the disk! they better watch out......

thanks again