How long are you glowing? Until the light goes out is not enough for an OM603 engine unless it is already warm from running. A good 10-15 seconds is better and if it is cold outside the full 30 seconds (or whatever) is recommended until the relay clicks off.

Home-made afterglow can be added to a non-afterglow preglow relay for the cost of one simple relay. See this thread for the details of how to do it. Although the initial installation of the extra relay was next to the preglow relay, I later moved it to the fuse/relay box where it is invisible.

I also added an "AFTER/GLOW" light to the instrument cluster so I can see when the preglow relay times out. When warming up the car, I wait until this light goes out (30 seconds) and then drive the car. The AFTER/GLOW light also acts as a warning -- if your preglow relay sticks in the ON position (very bad -- burns out glow plugs and runs down the battery) the AFTER/GLOW light will not go out.

You can also change to an after-glow relay ($$$), especially if you can get one cheap from a junkyard. Be sure that you have the right part number when you go junking and have the correct engine block temperature sensor for the new relay (others will know the details).

Jeremy

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"Buster" in the '95

Our all-Diesel family
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