When replacing glow plugs it is necessary to clean the glow plug aperture to ensure the new glow plug can transfer its heat to the engines incoming air. This is partiality due to carbon entering the glow plug bore.
Laser Tools 5746 Dummy Glow Plug M9 Compression Test Adaptor LL
Laser Tools Diesel Compression Test Glow Plug Adaptor - M10 x 1 x 147mm (#10) 72
Laser Tools Glow Plug Threaded Insert Kit M10 x 1mm 6779
LASER TOOLS Straight Ended Glow Glo Plug Connector Pliers
Laser Tools 7980 Oil Funnel Kit with Laser 9113 Drain Storage Station (9120)