Glow differences 300d vs 240d
 

This is not a problem, just a question. My 300d glow light has always come on for about 5-7 seconds when the car was hot or cold, and if it's real cold outside it may stay on for 10 seconds. Always starts fine and I figured it was the way it's suppose to be.
I have noticed on the 240d that the GP is a series system and uses the older "slow glow" plugs. When the car is cold it takes about 15 seconds for the glow light to go off, but when the engine is warm it goes off in about 1 second if you even see it at all.
My question, I was wondering if something is missing in the 300d that is letting the plugs glow when they are not needed, or is this just normal with the fast glow system?

Jim

The temperature sensor for the series plugs is in the head and for the parallel plugs it's in the relay. The GP almost always come on in the parallel systems, makes them easier to start.

The series plugs take longer to heat, even in the newer systems. On the 220D, it can take 30-40 sec to get the indicator good and hot.

Peter

I usually let my series system glow for a good time. I understand there is a parallel conversion kit out (bosch fast glow) but it uses pencil type plugs with the old style large threads. I heard you can't get replacements?

If I remember well the head temperature sensor is also connected to the glow plug relay
Is that true ?

I think the conversion kit uses a threaded sleeve that converts the hole to the size for the pencil plugs. Or you could get one made, for that matter, if you have a good machine shop around.

The dash temp guage is not connected to the glow system -- there is a separate sensor in the head for the systems that use it. Past 1980 (parallel plugs), the temp sensor is a solid state reisistor in the glow plug relay.

Peter