300se tapping noise
 

need some help on this one,have loud tapping noise in back of engine on my 89 300se,sounds like lifter but replaced all lifter's,still noisy,looked at cam lobes,they look good,sounds like # 5 or 6 cylinder,just started about 10 days ago,i tried swapping lifter's no luck,put old one's back in #5&6 cylinder's ,still noisylooks like plenty of oil getting there,i also reolaced all the ball cup's at valve's,everything looks good,cylinder head done about 30,000 miles ago with new valve guides and seal's and valve job,the engine runs great just loud tapping ,maybe rocker arm's bad although there free moving and clean,any help on this would be greatly appreciated,dont know where else to check,engine does have 280,000 miles on it but doesn't smoke or leak.

noise
 

I have an 89 300TE with the same type of noise. I have 200,000 miles on it, pulled the valve cover and everything looks brand new. Could it be a bearing in the lower end?????

tapping noise
 

well took the rockers off and swapped with another cylinder so i know it's not the lifter or rocker upon further inspection of the cam lobe on #5 exhaust looks like a worn flat spot on the cam lobe,a lot of miles on that cam and rockers,280,000,so i guess i will try to find a used cylinder head with cam and rocker assemblies and hope the cam and rocker's are better than mine with a lot less mileage,i will keep the head incase i need it later although mine was redone about 30,000 miles ago,new cam is fairly cheap but the rocker's are about 50 bucks each,(OUCH),i think i will be ok with used if the cam lobes look ok,wont know till i find one,we love this car and will keep for a long time.

noise
 

Doesnt look like anyone wants to help us!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Most likely flat cam lobe(s) if your car is 1986-1989. They had problems with cam hardness during those years. You should get a cam with matching rockers from a 90-up M103.

You would know for sure if it was a bottom end noise. Bottom ends don't "tap".....they KNOCK. :)

Our '88 has the M103, around 163K and so far, so good. Hopefully you will get it sorted out.

:o

Yeah, the design of the cam follower on the rocker will allow pretty smooth wear on the cam lobe, making it sometimes difficult to diagnose as a worn lobe. It's been my experience that when the hydraulic actuators begin to go bad, they generally peck loud at startup, then smooth out and quieten down.
Check the rocker pivot/shaft also; any loosness there will really tap.

As stated, try to find a later 103 cam and rockers; but do not mix older rockers/cam with new ones. The newer ones are surface hardened.

DG

rocker arms
 

are the bolts torgue to yield?

Nope. Torque spec for the cam pedestal bolts is 21 NM, or about 16 FT LB. Seems kinda low, but that's what I found in the service manual. Been awhile since I took one down.

DG

cam lobes
 

I have one flat cam lobe, can keep driving with this problem????????????????

Yes, it is safe to drive on, its not an immediate danger by any means. Most I've seen have multiple lobes worn and the car was running good otherwise. But I would replace it within the next 1,000 miles or so. The tapping noise will just get worse and worse as your cam eats itself. Again, be sure to get the matching rocker arms with the new 1990-up cam.