E320 camshaft breakage

[Neil Ross]

History of events leading up to camshaft breakage / E320 w124

One lady owner fails to notice cooling failure leading to the engine overheating and blowing the head gasket. Head is then removed by the mechanic, skimmed and replaced with new gasket. Mechanic then puts car onto ramp and runs for 1.5 hours to check cooling system is working fine (which it was) at which point the right hand cam snaps at the flywheel.

I have now taken the car of my ?one lady owner? friend in an attempt to restore this great car considering up till this point it has never missed a service and is under ave mileage.

I have tralled throught the forum and seen that a similar problem occurred to a members E320 and he concluded that the ?skimmers? had over skimmed leading to contact with the piston and subsequent piston breakage? Although would a breakage at the flywheel indicate this??

Who knows, but I would seriously appreciate any advice that would help me to narrow the source of the problem.
PLEASE HELP !!

 

[LNM]

You've put the fear of god into me now...

 

[flagstaff]

what kind of 'cooling failure' was it that led to the blown gasket??

can a cam snap 'at the flywheel'? do you mean 'at the flywheel end of the engine' ie the rear? or do you mean at the cam sprocket, ie the front of the engine?

it seems unlikely that a reputable engineering shop would have skimmed the head beyond specified limits ...

... first thing that occurred to me was that the mech had installed the head gasket incorrectly, possibly leading to a blocked oil feed to the head - and hence cam meltdown

 

[Johan]

... first thing that occurred to me was that the mech had installed the head gasket incorrectly, possibly leading to a blocked oil feed to the head - and hence cam meltdown

Had the mechanic put the head gasket on incorrectly, wouldn't the cooling system be faltering as well? It ran for 1.5 hours. Putting on a head gasket incorrectly blocks cooling fluid as well as oil feed to head.

at which point the right hand cam snaps at the flywheel.

Are you sure the timing chain didn't break first? This seems more likely to me than 'overskimming' the head, and could be caused by incorrect refitting of the chain.

 

[Neil Ross]

The timing chain didnt snap and the cam sheered at the front of the engine next to the fly wheel, if that makes more sense.

thanks for the suggestions so far

 

[AKM]

Do you mean behind the camshaft drive sprocket. The flywheel is at the back of the engine on the crankshaft