MBWorld.org Forums - ML63 AMG (W166) https://mbworld.org/forums/ 2011 -2015 (Replaced by GLE63) en Sat, 23 May 2026 06:48:09 GMT vBulletin 60 https://mbworld.org/forums/images/misc/rss.jpg MBWorld.org Forums - ML63 AMG (W166) https://mbworld.org/forums/ 2009 ML63 Headbolt Failure... What to Do? https://mbworld.org/forums/ml63-amg-w166/927549-2009-ml63-headbolt-failure-what-do.html Fri, 15 May 2026 23:14:48 GMT Hi all, Thanks in advance for your advice. I purchased a 2009 ML 63 last year. It is relatively low miles (~50,000). It has been a great driver, and it feels as well maintained as its extensive... Hi all,

Thanks in advance for your advice.

I purchased a 2009 ML 63 last year. It is relatively low miles (~50,000). It has been a great driver, and it feels as well maintained as its extensive service records indicate.

2 days ago, I received a low coolant warning. I topped this up with a relatively small amount of fluid, and the car drove fine (around 10 miles total). Yesterday, I again got the warning. Topped off again, but this time it took significantly more coolant. I became suspicious. The car continued to run normally for the next couple miles back home. At a light I noted a very slight roughness to the idle - like one cylinder misfiring. I immediately pulled into the nearest parking lot and turned off the vehicle.

It never overheated. I had it towed to a nearby specialist indy shop. He confirmed that there is coolant in the oil - not surprising. To my surprise he was dubious about the head bolts as the cause. Given totally normal behavior leading up to this, with normal engine temps (and normal rise with driving), it seems likely to me. He recommended to me that he start looking for a rebuilt motor. This didn't make much sense to me without pressure testing cylinders, bore scoping, +/- oil testing for potential bearing wear. I'm unsure if this is possible with contaminated oil, though I imagine it may be.

I'm obviously bummed. I really enjoy this car. I replaced all 4 air shocks just 2 months ago, and it is otherwise in very good shape.

My options seem to be: 1. Take to another mechanic who is willing to do more diagnostics to see what we are dealing with. Then, if all looks good (as good as it can), proceed with a bolt replacement + head gasket replacement, knowing that there is potential for further problems upon cracking into the motor (buckets, phasers, etc.).

Would anyone do anything different? At what point would you sell as is to a DIY-er?

Thanks!


****UPDATE****

Good news! Cylinders pressure test fine, borescope looked good. Found a reasonable indie shop, different from the first, with a lot of experience. We are going to proceed with a repair of head gasket, replacement of factory bolts with ARP/Weistec, and will address any other issues while in there (buckets, etc.).

Also, Mods, I accidentally put this in the wrong forum.. ]]> ML63 AMG (W166) Rkinderv https://mbworld.org/forums/ml63-amg-w166/927549-2009-ml63-headbolt-failure-what-do.html Vacuum Pump Extended Warranty MB https://mbworld.org/forums/ml63-amg-w166/926821-vacuum-pump-extended-warranty-mb.html Fri, 24 Apr 2026 14:13:09 GMT Hoping that the Document attaches here. This is regarding a new extended warranty on the vacuum pumps & transducer . I would like to let everyone know just incase.
Happy driving all.

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]]> ML63 AMG (W166) C43 Fun Haver https://mbworld.org/forums/ml63-amg-w166/926821-vacuum-pump-extended-warranty-mb.html