hard starting! - PeachParts Mercedes-Benz Forum

zoehelga · #1 11-26-2008, 10:15 AM

hi all,

this is my first winter with my '82 300D. i have new glow plugs, etc (well, new within the last year). she has always started up great, in warmer weather, and we've been struggling a bit in the cold. i live in the city so i park her on the street, hence no block heater. she always starts up eventually, but sometimes it will take up to 5 minutes to get her going. to add to the difficulty, my glow plug light is out so i kind of have to guess as to when she's ready to turn over...any input would be much appreciated. thanks!

also, does anyone else have a broken glow plug light? is it just a bulb switch out? the light being out doesn't affect her starting up...

rrgrassi · #2 11-26-2008, 10:22 AM

GP light out usually means two or more GP's are burned out, GP relay is toast, or the strip fuse has blown. Could be a burned out bulb as well.

Have you tried glowing the plugs with the driver's door open? You should see the light dim and about a minute later brighten back up. Doing that cycled the GP system. The GP ralay also makes an audible "thunk" when it closes and opens.

Have you tested the GP's? They should read less than 1 ohm resistance.

Have you adjusted the valves? Too tight valve clearances makes for harder starting.

zoehelga · #3 11-26-2008, 10:34 AM

thanks for the input...i haven't done any of those things...
the glow plug light rarely ever comes on at all, it's a once in a blue moon kind of occurence...i will try out all those things..thanks for the advice!

rrgrassi · #4 11-26-2008, 10:41 AM

No Prob,

Diesel Giant has a pictorial on testing the GP's resistance.

My car did the same thing. For me on plug shorted out, blowing the strip fuse. Of course it was during the winter, so numbed hands/fingers in the GP area is not fun. A ratcheting box wrench is the way to go.

I did not have aGP reamer, so I used a drill bit the same diameter as the GP tip, and by hand reamed the holes.

Make sure you use either Bosch or Beru GP's

zoehelga · #5 11-26-2008, 11:36 AM

ok thanks. after the first start up that takes awhile, she'll start right up no problem, even if it's really really cold out...so it's like once she's warmed up, theres no problem, what's with that?

rrgrassi · #6 11-26-2008, 11:44 AM

Sounds like GP's along with valves that are too tight. I still need to have the injectors pop, pressure and spray tested. I could not find anywhere in my paperwork indicating thiswas done. It is possible I have 256k miles on original injectors...

dieselnutnj · #7 11-26-2008, 06:52 PM

I would lean towards the glowplugs definitely before anything else. If you have a test light, or a volt meter, place it on one of the glow plugs and turn the key on. Your test lite should light up or the volt meter should be above 10 volts. If your lamp is out, you may indeed have a defect in the gp relay. I dont think you have an injector issue, but if you want to check valve adjustment it can't hurt. It is a very common thing for the valve clearance to drop drastically as the car ages. All that you are saying ie the hard to start cold starts ok warm.. sure looks like glow plugs. Heat is a diesels best friend, the glow plugs preheat the combustion chamber to allow for easier starting. If your not all too familiar on how a diesel operates, check a few links and I'm sure there is a great detail on it. They are neat engines!

happy turkey day!!!!

ARNOLDLewis · #8 11-26-2008, 07:38 PM

Cold engines might experience problems at the time to start due to different reasons. One of these reasons can be based on the effect which cold has on liquids evaporation. When it is cold, gasoline evaporates less and this cause it to be more difficult to burn due to the fact that it is burnt when it is evaporated.