Ya everyone of my plugs squeaked and were so punked up it was hard to pull them out.

I think this was just carbon tho. Although if the mehyle plugs have the thinner diameter tip like the Bosch ones do then they definitely did swell. But I think the mehyle ones are just made that way

Questions about brand of GPs.
 

Have Bosch GPs ever given anyone problems excluding carbon in buildup on in the holes?

I've used them exclusively for nearly a decade without issues. I usually change them every two years without testing and I've never had starting issues with my 617.

I have Bosch GP's in the SDL and they haven't given me any problems in 2 years. The 603 is a PITA to change the GP's on, so I won't be changing any until I have starting issues.

I've had the same set of Bosch plugs for 7 years and no issues. Whenever I'm working in the area I pull them out and ream the holes but that's it. I have yet to see any major issues reported, like the swelling or whatever.

-Rog

See post #7
http://www.peachparts.com/shopforum/diesel-discussion/309096-glow-plug-help.html

Not just on mercedes see post #1
https://www.ford-trucks.com/forums/1012909-wap088-dual-coil-glow-plugs-photo-after-test.html

Please see the pics in post #3
http://www.peachparts.com/shopforum/diesel-discussion/382267-95-e300d-fully-unthreaded-but-stuck-glow-plug.html