In the event of a broken glow plug in the cylinder head the comprehensive glow plug removal kit (p/n 5205) from Laser Tools will let you drill out and grip the remaining glow plug body to pull it out of the cylinder head. It is strongly recommended that the cylinder head is removed before commencing work.
The first job is to remove the top connector and the broken hex from the glow plug. A star socket is provided in the set which is just the right size to grip tightly onto the connector when gently tapped into place with a hammer.
Then use a 3/8″ ratchet handle to turn and break off the top connector. The plastic insulator and the broken hex can now be prised off of the electrode.
Grip the central electrode and twist it out. Sometimes this electrode will shear off with the hex, leaving the remainder of the electrode in place. In this case the electrode has to be drilled out before we can continue to remove the glow plug body. A centring sleeve and drill bits are provided in the kit for this purpose.
Two dual-sized step drills are in the set; choose the correct one for the size of the glow plug. The smaller guide drill will fit snugly inside the body of the glow plug and the larger drill is the correct size to drill out the top section of the glow plug without damaging the threads in the cylinder head.
To ensure that only the threaded top section of the glow plug is drilled out refer to the new glow plug to be fitted and mark the correct length of the threaded portion on the drill bit. When drilling, do not drill down any further than the mark.
Drill out this top portion of the glow plug body down to your mark on the drill. Take great care to keep the drill bit straight and parallel to the glow plug in the head. A drill extension is provided in the Laser set to assist if access is difficult when working in-situ.
Clean out the remaining glow plug thread material from the threads in the cylinder head. Then clean and restore this cylinder head thread by using either the M8 or M10 taps provided in the set; fit the tap to the ratchet Tbar and carefully chase out the thread — use grease on the tap to lubricate the cut and to hold the swarf — the ratchet T-bar provided makes this a very easy task.
Now we are going to cut a new thread in the part of the glow plug body that is remaining in the cylinder head. This will allow us to screw and secure the puller onto the glow plug body. A 1/4″ tap is provided for this. Again coat the tap with grease and steadily cut the new thread down about 10-15mm into the glow plug body. Keep the tap straight.
The remains of the glow plug body can now be removed. The puller mandrel is screwed into the newly cut thread. Nip it up with an 8mm spanner. Then the puller is assembled onto the puller mandrel.
Screw the force screw onto the mandrel first, followed by the outer housing of the puller. Adjust so that the outer housing is against the cylinder head and run the large force nut down the force screw until it rests on the bearing in the puller.
Hold the force screw steady with a 12mm spanner and turn the large force nut clockwise with a 30mm spanner. This action draws the puller mandrel and glow plug body out of the cylinder head. To finish, clean the area very carefully to remove metal swarf and debris.