Devastated. No compression cylinder 3
 

Was driving to work and my CL63 shuddered and stopped. Took it to my Mercedes tech and he reported no compression cylinder 3. Not sure if I should keep him digging to see if it’s something that can me fixed or source an engine.

Next question would be... can I drop in a biturbo engine?

Anything is possible with enough time and money. Contact a big name tuner to see if they can tune or create a custom wiring harness for the new engine using your old ECU. It will be easier and probably cheaper to swap in a used engine and ditch the car.

I found 2 M156.984 engines. One with 35,000 miles and one with 55,000 miles. Both same price just under 7k. I have a fantastic Mercedes mechanic and I still owe 15k on it so i'm not just ditching it at this point.

While the engine is out, have your mechanic update the headbolts.

can't bad valves cause a no compression scenario? im trying to understand why you're deeming this engine a total loss already. are valves not replaceable?

Its a cost thing at this point. He thinks there could be a valve issue but the piston is cracked, no compression... If i try to repair it, i need head bolts, intake manifold since both are old and in need of replacement and likely 100 other things in a 110,000 mile engine. I can buy a 30k mile engine for 6500 right now and plug it in...

Don't try to rebuild. Used drop in engine is your best course of action.

im often a huge advocate of swapping in a good used engine on these cars VS. major engine work, especially since my AMG swap, i've been nothing but satisfied ever since. just wanted to make sure you weren't overlooking anything before considering this engine a loss....was just watching one of LegitStreetCars videos on youtube where the dealership deemed a great s55(?) a total loss over a simple repair

My mechanic is solid... he’s going to open it up to make sure but it’s a cost issue on a 100,000+ engine

Don't let him try to rebuild or repair if it is a cylinder or piston issue. Just drop in the used engine and go. Again, make sure he does the head bolts and head gasket before dropping back in the car.

BlownV8, what would prevent a rebuild in the case of a failed piston?

If it damaged the cylinder wall and you had to get oversized pistons, you are better off putting in used. If the piston walls are not damaged, you could drop in a new piston. Problem is, labor eats you up on repairs vs swapping the engine. Plus, you have the variable of the mechanic doing the work properly.

Exactly. We are opening it up to see cylinder wall. The mechanic is one of the best Mercedes mechanics in Florida.

New engine installed... runs great...

Did you get a chance to open up your old motor and see what the problem was?

Valve stem when into the cylinder and scratched the wall. New motor was put in.