It seems Mercedes Benz has an issue with the normally aspirated 63AMG engine that they are not sharing.
This is the second engine that we have seen that exhibits exactly the same failure at roughly the same mileage. This engine came to us in an SL63AMG with approx. 53K miles. The customer experienced a sudden loss of power and lots of white smoke out of the rear end. Thankfully, he stopped driving it and towed the car to a Mercedes Benz dealer.
The dealer recommended replacing the engine – however, our customer’s warranty company didn’t agree, so he came to Rennology to get a second opinion. On inspection we found the same problem we have seen before. The head bolts on cylinders 7 and 8 failed – the top of the bolt literally broke off. (see photo below)
Broken Head Bolts on Cylinders 7 and 8
Look Closely – The head bolts are missing
63AMG Timing Gear
This caused the head gasket to fail and coolant to enter the combustion chamber – hence the loss of power and white smoke. Thankfully, with the engine being as strong as it is and the customer catching it quickly, the engine recovered fully after the head bolts and head gaskets were replaced. The images below show the improved engine being re-installed.
Replacement engines for AMG cars can quickly exceed the value of the car. However, in this circumstance, we were able to save the engine and our customer from spending a considerably large amount of money.
If you have a Mercedes 63 AMG engine, watch out for this failure and don’t be persuaded to replace the engine without a second opinion first!