To try and keep a long story short, I have a 1985 300sd and a 1984 300sd. The 1984 starts up fine. The 1985 will not start unless you cycle the glow plugs at least 2 times and I am talking full time even after the glow plug light goes out I watch the dome light brighten then crank. I have replaced the glow plugs, and noticed that they were hard to remove. Could carbon build up cause this problem? Note both cars have about the same mileage 325,000. I did not have a reamer, but if I did use a reamer, where would the crud fall? Suggestions and comments welcome. Thanks

What brand GP? Have you done a valve adjustment lately?

Yes, carbon can act as an insulator, causing premature GP failure and keeping the cylinder from heating up fully.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 133K miles-replaced the other '06 that quit after 300k miles. (did not catch the bad cam in time)

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 195K

90 Dodge D250 5.9 Cummins/5 speed. 400K

You can do like I did,take a old glowplug.Hammer a flat end on it.Grind it to where it sharp,but only .030 oversize standard glowplug.Gently screw it in,you may have to force it, to break carbon.And unscrew,then turn engine over a couple of times to blow out carbon.Remmember size of your reamer should not be as large as threads.

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veteran, hippy, will always be, but will fight for the under dogs