Carbon Buildup Removal

[Eric Sullivan]

Does anyone know why the engine will not turn, hand cranking, after I removed the carbon from 4 of the intake runners. It is like it hits a hard stop and will not turn any further, I have not tried cranking with the starter, afraid it will damage the engine. I am sure there is no walnut media trapped in the cylinders as I have removed the injectors from the cylinders and can see there is no walnut shell in the cylinder. This is the 2011 BMW 335d. Thank you.

[marvinstockman]

Pull all the plugs, and try to hand crank for a few turns.

[Eric Sullivan]

No spark plugs, it is diesel.

[dworthy]

Do you have a small camera or bore scope? I am thinking a chunk of carbon has gotten caught between the valve and the head, not allowing it to close all the way. Have a look at each intake valve, if you are not able to find anything, take a look at the where it the engine stops, for this can indicate which cylinder it is having problems with too.

[jclausen]

Second the camera if it was running before you did something during the repair

[marvinstockman]

Then pull the glow plugs.

Also, with glow plugs pulled, crank over as far as you can, then back off, then crank, then back off, then crank. Keep doing it, and the blockage may break up.

[flemm2]

Sounds like mechanical binding to me too. Hard to determine though without more detail regarding the carbon cleaning.

You could try spraying penetrating oil into each fuel injector gland and/or into the intake ports on the cylinder head cover, wait a couple hours and try to crank the engine by hand again.

But if there wasn't any walnut in the cylinder, maybe electrical? Have you tried putting the key into the ignition w/o starting, if so what displays on the instrument cluster? Maybe you activated the engine immobilizer/anti-theft system?