For what it is worth, the first winter after I first got my '84 300D started horrendously. The car nearly refused to start no matter what. After a valve adjustment, things were improved markedly. I also replaced the glow plugs and checked the relay for good measure. I still had the occasional problem when the temperature got below about 20 degrees. This year I switched from 20W50 dino juice to 15W50 synthetic, and it starts just like a warm spring day, every day. Entirely worth the added cost.

-Reed
'84 300D/T 145,xxx
'01 Saab 9-5 LPT wagon
ex- '81 300SD
ex- '82 280TE
ex- '91 300E 2.6

The heaters in the Dodge Cummins Diesel are rated lower than 12 volts. They use these GP so they heat up much quicker than 12V heaters would. The controller keeps them from burning out by switching them on and off. They GP in my Chevy Detroit Diesel work the same way. They are 6 volt GP that heat up quickly and are switched off and on so they don't burn out. The controller failed and all the GP burned out. Since the controller was so expensive, I put in 12V GP and a switch to turn on the GP.

The GP in older MB that are automatically controlled, stay on about a minute even though the dash board mounted light goes out sooner. As soon as the starter is released, the GP are disconnected. However, some of the newer models leave the GP on a short time after the engine starts. The MB GP are 12V so they are not switched on and off to regulate them.

I'm not sure how the Datsun or VW GP work, so I will take your word for it. But it seems odd that the GP would be shut off while the engine is being cranked by the starter since you usually energize the starter after the GP light goes out. If the engine didn't start immedialtely, it wouldn't start because the GP cool rapidly.

P E H

The VW system is the same as the Volvo TD -- glow plugs stay on after the light goes out for a time period determined by the temp senor in the back of the head and the relay. They stay on while cranking and after then engine starts -- you can tell how long by when the headlights brighten.

If the relay goes bad like mine did, and the glowplugs stay on all the time, the battery will go dead with the headlights on! Quite an experience, and amazingly, only two of the glowplugs completely died!

Peter