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Discussion Starter #1
My 1980 240D, 4sp Getrag started giving very bad diesel mileage. It used to run 27mpg-31mpg combined. After glow-plug change, it has been running at 23mpg combined.

Why the change:
The glowplug light started blinking for about 10sec after the engine starts, which I read means one of the glow-plugs died out. I went out and just bought 4 new ones to change all ones.

New ones: Autolite 1103 - Replaces: ACDelco 30G, BOSCH 0250201001, 0250201005, CHAMPION CH68, MOTORCRAFT

Old ones: Bosch

My question is, could the very big change in the mpg be due to the glow-plug change? Should I go out and get 4 new Bosch glow-plugs? No other changes have been done to the car and the drop in mpg started right away. No changes in driving style or route.

Cheers.
 

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Did you disconnect any of the throttle linkages? Any noticeable change in the way it drives?

Did all four old glow plugs come out intact or were there any broken pieces left inside?

I would have recommended Bosch or Beru instead of Autolite.
 

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Discussion Starter #3
One of the new ones didn't go in easily so I had to force it, it might be too tight/too much.

No changes in driving.
 

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On the W123 617.952 Engines that Autolite Glow Plugs are the worst possible ones to use.
I had bought some and had them in my Engine before I read about that.

When I changed to the Autolites I did not have a Glow Plug Reamer to ream the Carbon out of the Glow Plug Holes. I installed the Plugs any way.
6 months later I bought a Glow Plug Reamer and removed the Glow Plugs so I could use it.
I barley got 2 of the Autolite Glow Plugs out of the Cylinder Head. The tips of the 2 Plugs had become swollen.

Later I saw pics on one of the forums where the tips of the Autolite Glow Plugs actually looked as if they had exploded.

I also tried Monark Glow Plugs but enough of them died out too soon I replaced them with Bosch.

So I have settled on using Bosch.

If you did not clean the Carbon out of the Glow Plug Holes that could be the reason the new ones went in hard.
Glow Plug Reamer or some alternative method to clean the Carbon out.

Every year when the Winter Diesel Fuel comes out some complain of decreased milage. The antigell addatives do not have the same amount of energy when the burn as the Diesel Fuel does.
 
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