My 1991 300E has a problem--I can't get the spark plug wires off. Cylinders 1 and 3 came off with a normal amount of effort; cylinders 2, 4, 5, and 6 are very stubborn. I managed to get wire #2 off with a lot of force using plug wire pliers. Now that I have changed plug #2, I can't get the wire to reattach to the spark plug; it won't "grab" and there's no friction. I suspect my wires are toast; is this the case?

Replacing the plug wires is probably beyond my level of expertise. If I can't get the wire back on, do I need to get it towed two miles to the shop, or can I start it and drive it with the #2 cylinder out?

Thanks for any and all help you can provide,
p. rex

You can do it, just do one wire at a time. I would not drive it until you get those wires replaced.

It sounds strange that wires that were so tight now have no grab at all. Do you have the little caps on the end of the plug? If the ends are somehow deformed you should be able to crimp them with some plyers to make them tight again - at least tight enough to drive a few miles to the shop. Or replacing the wires is not that tough a DIY job - just pay attention. You don't have to put all the wires back into that silly plastic channel on top of the valve cover.

I had that problem once....just a dumb question..did u take off the cap of the spark plug? Sounds like maybe someone didnt when they put the wires on-god if they did I cant imagine...but a good pull really should remove the wire...and if you have had this problem, maybe they did also, and never bothered changing the plug. Get a set (99.00) at best, and you will be happy you did.

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Timothy Evans
TimEvans35@gmail.com
CELL 310 990 6780


1985 380 SL
2010 CL 6.3 AMG
*2009 CL 550 Sport 4matic
New addition-1984 380 SE
Newest Edition 1986 300E AMG

Well, I've found the problem. Apparently, the terminal on the spark plug is threaded, and mounts on a screw on the top of the plug. The plug was impossible to pull off because this terminal was frozen somehow to the plug wire boot; I got it off by twisting the terminal off the spark plug with the boot. This is not a good situation; the plug wire boot won't mate to the new plug because it still has the old plug's terminal inside.

What in the world could cause these terminals to become so completely stuck together? Anyhow, since time is in short supply, I think I will replace the old plug, and screw the boot and corresponding terminal back onto the old plug, so I can get it to the shop for new wires.

p. rex, as Dean mentions replacing ignition wires on a 300E is a fairly simple DIY job. In your case I would replace the distributor cap, distributor cap gasket/O-ring, distributor rotor, ignition wires and spark plugs because it sounds like your engine has been neglected. When installing the new ignition wires apply a light coating of dielectric grease inside each boot ... that will make future removal much easier.

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Fred Hoelzle

You can buy a spark plug cap puller (about $5,-). This makes it much easier. Make sure You buy the angled one to reach the caps in the rear.

Rob