300SDL glow plugs

Jul 15, 2003 2 Replies

My 86 300sdl left me stuck the other day when the glow plug light would not come on. I found the fuse in front of the drivers side wheel-well on some sort of black box (about 2x4x4 inches) was discolored and bent but not broken in the middle. I replaced it and the car started fine. But under one of the terminals of this fuse, the black plastic housing is deformed and partly melted. Could this be the sign of another problem somewhere else or could it just be from age and wear? Anything else to look for that could cause this? TIA, Shannon



80 450SL 216k
86 300SDL 282k

The "black box" is the glow plug relay. If it "acts up" you should know that Bosch and Beru make retrofit glowplug relays that extend the glow time in order to reduce smoke at start up. These may be cheaper than an OEM replacement.

According to the manual (somewhere), my 87 300SDL already uses the glow-after-start relay, though I am not sure about 86. "T.G. Lambach" wrote: The "black box" is the glow plug relay. If it "acts up" you should know that Bosch and Beru make retrofit glowplug relays that extend the glow time in order to reduce smoke at start up. These may be cheaper than an OEM replacement.

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