The useful tool costs $391. I thought I was a bit extravagant when I paid $23 for the snapon socket, which works better for removing my glow plugs than my Craftsman deep sockets.

My bad, my eyes were drawn to the MSRP $599. I didn't check the price in cart.

What feature made the snap on deep socket work so much better? Material? Fit?

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

I bought a '98 e300 about 10 and one-half years ago and have changed the glow plugs twice in the last five or six years. The first time I used a quarter inch drive deep Craftsman socket to remove four of the glow plugs and a three-eights inch Craftsman on the other two. The determining factor was the ease of use considering obstructions. I didn't use heat either time but did use liberal amounts of a penetrating oil (P something Blaster).


After the first change, I read several posts by Len Sokolof on the MBCA and this site that recommended an intermediate length Snapon socket for this job, so I bought one. It's model number is 12 Snap-on FSM 12 USA. It is a three-eights socket that is shorter than either of the Craftsman sockets -- making it easier to navigate obstructions. The principal difference though is that it has a sleeve inside the socket that doesn't permit the socket to go any further (deeper) than the hex part of the glow plug. That is an important difference.


The reason it is important is that the glow plugs are recessed in what are essentially tubes. The Craftsman sockets go deeper than the hex part of the glow plug, and I think they bind against the sidewalls of the tubes or against where the glow plugs are seated. I think this binding makes it more difficult to remove the plugs, and in removing them you don't know whether the force being used is due to the binding or due to a seized glow plug. The snapon socket removes any binding effect from that determination.


The snapon socket is well worth the cost.