last night driving new to me 83 240 D i noticed that the glow plug light would come on and off any ideas on why this would happen ?

Could be a bad glow plug. Supposedly they will flash the glow light if one dies, I think on #1 cylinder.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Are you having symptoms of a bad Glow Plug like hard starting or an uneven idle after you do start that lasts for minute or so and goes away?

My Glow Plug light dissapeared completely for the most part of a year but I had no symptoms of a bad plug so I knew they were working. The light came back on by itself afternearly a year of not working.

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84 300D, 82 Volvo 244Gl Diesel

Not if the light is coming on while driving.

No.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Possibly an electrical problem that is causing the glow plug timer to intermittently initiate the glow sequence.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Does the gp light glow normally during the starting sequence?

- Peter

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Yes the glow plug sequence works as per normal

Starts right up no hard starting

I have a '98 e300 so my experience might not be helpful. When I have had 1 bad glow plug, it starts right up and runs rough for 10 second or so, with some bad smoke from the tail pipe. With two bad glow plugs, the car starts right up but runs rough for 20 to 20 seconds and I get lots of smoke from the tail pipe.


The outside temperature is also important. The period of rough running is amount of smoke is less at 50 degrees than below that temperature. Below 40 degrees, it runs rough for 30 seconds and I get more smoke. I've never tried it below 30 degree, but I would expect longer rough running and much more black smoke.

The outside temperature is very important. In southern California, where you live, a diesel might start up pretty well even with a bad glow plug or two.

After my recent glow plug issues and starting problems I'm now of the opinion that it's not worth mucking about guessing about this stuff. Just buy a new set of Bosch Duraterm plugs and put them in. That way you will know the plugs are good and any other symptoms can be traced without that being in the mix. Then you can test the old ones and keep however many good ones you have as spares.

Has this issue of the light coming on while driving manifested itself all the time or just once?

- Peter.

__________________
2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

If the glow lamp is illuminating while driving, the problem has nothing to do with the glow plugs themselves. Replacing the glow plugs would accomplish nothing. (Believe it or not, the glow plugs are not "tested" periodically while driving.)

Most likely, a poor electrical connection (possibly the key switch) is causing the glow timer to initiate the glow sequence, just like happens when the key is moved to the glow position. A temporary loss of power will cause the timer to "think" that the key has moved from RUN to OFF and back to RUN.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Various dash lights come on when we wind the RPM's up to high in our '81, it just lights up like a Christmas tree.

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.