it glows, then it doesnt glow, then it glows... what the heck!!!! - PeachParts Mercedes-Benz Forum

75mercedes07 · #1 01-16-2006, 04:00 PM

so half the time i try to start my car the filiment in the salt shaker glows, then half the time it doesnt. i went out just today, i let it glow for a while, and then tried to start it; its started and then just turned off a second later. so i tried to glow it again, but it failed to glow. the odd thing is i still tried to start it and it started right up. with the inconsistancy of glowing though, i dont dare to drive it anywhere too far where it might sit for a while in the cold. i dont know what to do. i am having my dad go and get a filiment from another 240D that we know works. could that be the sole problem?

rachelle

Krueger · #2 01-16-2006, 04:07 PM

I'm assuming the "filament in the salt shaker" means the glow plug. New glow plugs are certainly essential for start-up, however it sounds like your relay may be faulty - or at least the wiring.

75mercedes07 · #3 01-16-2006, 04:17 PM

well, we just did a glow plug change not too long ago. we put the new pencil style glow plugs in. so that should be ok, we did have some difficulties wiring things up at first, but they are all good now. thats why its so confusing.

how can i check the relay?

Krueger · #4 01-16-2006, 04:32 PM

The relay on your '75 should be under the steering column - probably silver in color. If the plugs are inconsistent in glowing, or the glow light doesn't always come on, you might as well just buy a new relay. A lot of people like to putz around and test each individual component, or each individual wire, but believe me the $100 you spend on the relay for this car will be well worth it.

75mercedes07 · #5 01-16-2006, 04:38 PM

should i wait and see what happens with the new filament? i dont know for sure if i want to just jump in on another $100 purchase. i dont have that money right now

Krueger · #6 01-16-2006, 04:48 PM

I understand about the money thing. I would see how things go once you install the new plug. I had a faulty relay in my '77 300D one time that showed the same symptoms. The plugs would glow sometimes, and sometimes they didn't. If the glow light didn't go on when I first tried to glow the plugs, I just kept trying until the light went on. You could also try a junkyard where you may get lucky and find one for cheap.

If you ever get desperate or get stuck somewhere becasue the relay failed, it's always a good idea to keep a piece of 8ga wire in the car. You'll be able to glow the plugs by placing one end on Plug #4 and the other on the positve battery terminal. It's a pain, but could get you through until a new relay can be purchased.