2014 ML-350 with 102,000 miles. Have owned since 8 miles. Run solely on E-85 as indicated as an acceptable fuel. After B Service last week at Knauz on p/u check engine light was on. Tech told me they had been seeing when cars washed and they sit (never experienced it before). Checked and reset light and said nothing and sent me on my way. Next day light came one. Monday light was on, called couldn't get loaner until later in week, said fine to drive. Every fourth time starting the car would idle rough, like a miss. Could shut off and restart and it would go away. Took back in and they ran diagnosis. Determined it was #5 cylinder. Moved coil and spark to other cylinders to determine if faulty components, still #5. Tech tells me today 90% compression, but that they haven't tested it. Will be doing so and if case may need to replace cylinder head. Tells me at this mileage its expected, seems soon. Reasonable? E-85 issue? What's the cost of a cylinder head replacement?
My car has 102000 miles.
My car has an automatic transmission.
Before having the cylinder head replaced, check the compression on all cylinders. What you are looking for is that the compression is 120 psi or more and the first puff of compression is half of the max puff of compression. If the compression has checked out to be good, then check the cylinder head out with a leak down tester. This will determine if the head gasket is burned, if a valve is bent or burned, or if the cylinder piston rings are worn. If you need further assistance with diagnosing a failed cylinder head, then seek out a professional, such as one from Your Mechanic, to help you.
Sent billing question to CS for the cost of a cylinder head replacement.
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