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2000 ML430
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Discussion Starter #1
I went to replace leaking valve cover gaskets yesterday, but got more than I bargained for, and not in a good way. I'll let the attached pictures explain.

I have been experiencing a misfire from cylinder 7 for some time now, namely and in order P0300-080, P0307-087, P0300-067, and P0307-074. I replace all spark plugs on the odd banks several months ago when the misfire first started, and switched ignition coils to see if code travels - code did not travel - and I still have the misfire issue.

I'm wondering if the misfire codes might have anything to do with what seem to be some kind of a damage. Would I need to replace the cylinder head?

Help!
 

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2000 E55 AMG
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85 Posts
Are you getting the misfire on the cylinders with the Burnt (?) rocker arms? I don't see why you would need to replace the head for that unless there is physical damage.

From what it appears is that the shaft mounted rockers are getting REALLY hot. You may possibly have a blocked oil passage that may be causing the rockers to get hung up and not closing the valve fast enough. I'm not very familiar with that engine, but is there a way you could remove that shaft with the rockers and give it a thorough cleaning? Paying close attention to the oil passages.
 

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2000 ML430
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Discussion Starter #3 (Edited)
The misfire is only coming from one cylinder, cylinder 7, and the burn is shown on that rocker arm. Burns are also on the arm at cylinder 5, and it seems somewhat at cylinder 1. The picture is of the left cylinder head which has all odd banks - 1, 3, 5, 7. I just left the parts department at the Benz dealer and the parts guy told me a need the entire left cylinder head assembly after showing him my pictures. He says I would also need to order 24 valves and potentially other stuff at a cost totaling roughly $3500 in parts.

Regarding the cleaning bit, I don't know what can be done. Does anyone knows if this can be removed and cleaned? If so, could you please post instructions and/or pictures.
 

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2005 SLK55 AMG
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253 Posts
It may be possible to rebuild that head.A compression/leakdown test would be advisable before throwing $$$ at it...JMO.Replace or rebuild , either way the head will have to come off. If you're capable you could pull the head and take it to a good mechanical shop and get their opinion.Could a leaky valve cause that? Could a plugged CAT cause enough back pressure to blow out around an open or damaged valve?

It is a scary problem.Good Luck !
 

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02 ML320 06 ML500
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The misfire is only coming from one cylinder, cylinder 7, and the burn is shown on that rocker arm. Burns are also on the arm at cylinder 5, and it seems somewhat at cylinder 1. The picture is of the left cylinder head which has all odd banks - 1, 3, 5, 7. I just left the parts department at the Benz dealer and the parts guy told me a need the entire left cylinder head assembly after showing him my pictures. He says I would also need to order 24 valves and potentially other stuff at a cost totaling roughly $3500 in parts.

Regarding the cleaning bit, I don't know what can be done. Does anyone knows if this can be removed and cleaned? If so, could you please post instructions and/or pictures.
First of all the left cylinder bank houses the 5-6-7-8 cylinders, so you probably changed the wrong coil. Replace whatever you switched back to its proper place and then swap #7 coil with any other coil and see if the problem follows. If not, swap spark plug wires to another cylinder being mindful of where they come from and where they are placed on the coil.

Secondly, whatever appears on your rocker arms would have nothing to do with a misfire. Replace your valve cover gaskets and forget about what you think is a problem.
 

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Discussion Starter #6
Thanks 43sqd for the correction and instructions. I did replace the valve cover gaskets as advised. I won't be able to run any test to examine the misfire issue until I get back my traction control module which is out on rebuild for a second time for a C1000 code. I did notice, after careful inspection, that the ignition coil on the cylinder that is misfiring seem be coming apart. I'll take a picture and post it tomorrow. Thanks again.
 
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