Mueller-Kueps MLK600248 Glow Plug Drill Kit (M8x1)

I’ve had moderate success with 3.0 sprinter diesels. First off you need to be perfectly inline with the broken glow plug or you will drill off kilter. I’ve done both depending on which cylinder. To date I’ve extracted 12 glow plugs and the majority have been cyl 2. If you drilled dead center the m8 threaded drill bit will not damage the cylinder head threads, but if you drilled the slightest bit off there will be a thin piece of threaded glow plug you will need to break off (gotta get creative with a pick. Once you’ve removed the threaded portion of the broken glow plug, then you use the left handed bit to drill into the seized glow plug. This is where you need the slide hammer (not included), I welded a bolt to a rod and used a 3” 3/4 socket for a homemade slide hammer, which sometimes breaks it loose or breaks the glow plug off in sections. If it comes out in sections, this is where the fun begins, because the sprinter glow plugs often have carbon creep up the shaft essentially gluing the glow plug to the head. I normally had to fill the hole with a 50/50 mixture of ATF and brake fluid and start the engine up to heat cycle it and allow the mixture to attempt to penetrate the carbon. You will notice some compression passing through the hole but do not hover over the glow plug while the engine is running because the glow plug can shoot out violently and cause injury, instead use an inspection mirror to monitor progress. If this fails to blow the plug out, you will need to drill, tap, and slide hammer it some more. Eventually it should come out with patience, LOTS of patience. Typically if it’s really stuck you will booger up the threads of the glow plug and it’s highly recommended to have both an M8x1 helicoil set and some m8x1 timesheets in hand depending on how much you struggled to get the plug out. Overall I give this kit a meh rating because I’ve had success but lots of aggravation to accompany it and the fact it’s pretty expensive and doesn’t include a slide hammer. I’ve went through 2 of these kits so far due to the main bits tip breaking off. Things I’d improve on would be skip the slide hammer and include a left handed threaded stud with a bearing to apply a constant and steady force to help removing the glow plug especially which trying to blow them out with the engine running. I do find the bits cut smoothly and well, just be careful and drill at low speeds, I probably broke the main bits due to impatience to be honest, but next one I order I’m going to fabricate a puller instead of slide hammering it. I’ve included a picture showing extracted glow plugs