Valve gear hitting valve cover

[Nicolas Aristodemou]

Please have a look at the photos below. What could be the reason if this severe interference?  Engine seems to run normal apart from this noise which I initially thought would be due to rocker cover fixing brackets interfering with camshaft.... but this was not the reason..... valve rocker on no 2 cylinder visually looks thicker ...... how would that be possible? I think my engine has been running like this for at least 10,000km  Problem seems to be with cylinder 2 intake valve rocker hitting rocker cover breather channel.....

[stickandrudderman]

I have never seen that before.
I wonder if the top face of the head has been machined and possibly cam bearing shims added. Both of these will reduce clearance between rocker and cover.

[Pawel66]

I am certainly not qualified for diagnosis, can only guess... I understand the top left rocker is thicker, right? What if someone fitted a different rocker and, knowing it is thicker, just tried to make some space for it by hammering on the breather channel?

[Cees Klumper]

My speculated guess would be something catastrophic happened that caused this deformation to the valve cover. Maybe not even on this engine, but another one that the cover was on at the time.

[Nicolas Aristodemou]

I would tend to agree with Cees that it could be the result of an earlier catastrophic failure of the engine valvegear before I bought the car. I have not found myself any metal debris in the engine either. My engine was fully rebuilt 4 months ago and has done more that 2500miles since. Runs fine apart from the valve gear noise. When I have the valve clearances adjusted noise seems to become much less only to come back soon afterwards, after covering a few km. Surely there is no interference between valve cover fixing brackets and camshaft. Only thing I regret , when engine was being rebuilt , was failing to note the state of the engine breather channel inside the valve cover. These severe dents must have been there and nobody noticed them. I will clean the valve lifters and paint their ends white , then would run the engine for some 200km and reinspect, just to see if any of the paint would be scraped off. I should however look for alternative ways of curing the valve-gear noise, especially audible at idle speed...... thanks you all for the inputs, will update on the progress -if any-......

[Nicolas Aristodemou]

Following my latest post, I marked with white paint the intake valve rockers for cylinders 1,2 &3 and drove the car for a round trip of about 150km. Upon opening again the valve cover I didn’t notice any white paint either leaving the rockers or being deposited on the valve cover breather channel.  This has confirmed what  Cees had suggested that these dent marks could had been the results of a catastrophic failure of a valvegear component that happened long time ago possibly during a previous ownership of my car.

Furthermore, I adjusted the valve clearance myself and found all valves to be very loose. To the point that I questioned if my mechanic had adjusted the clearances using an inch feeler gauge rather than a metric one. Once the clearances were properly set I got rid of all valvegear clutter. So all is ok again...... thanks for everybody’s help.

[Cees Klumper]

Thanks for the update. And good that you checked the valve clearances!

[MikeSimon]

Coming back to an earlier remark: Is there a rocker arm variant that is "thicker" or of a different dimension and still would fit on the SLs?

[Nicolas Aristodemou]

In my car there are at least two rocker arms that are different from the rest. Don’t know where they sourced from. Normally they should all had been the same....