The 648 motor is much better than 606 for changing glow plugs. I've broken off a glow plug on my previous 606, then successfully changed others on the 606, as well as successfully changed GPs on my 648.

The key to success is three things...lots of PB Blaster, warm engine, torque wrench. You don't need to soak it weeks ahead, hours is OK. Engine doesn't need to be hot...warm is OK. Torque wrench is important...don't exceed about 40 Nm of off-torque. If it doesn't break free at 40, stop, spray more PB blaster, wait. repeat. It just takes the discipline to be patient.

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Mark in MA
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