Quick Glow Plug questions - PeachParts Mercedes-Benz Forum

adiaw83 · #1 12-24-2004, 05:44 PM

My car has stopped starting and I'm pretty sure its the glow plugs. This time though the light on the instrument cluster doesn't come on at all when I have the key in the charging position. Does this indicate a possible relay problem? I haven't had time to do anyhting other than try to start the car so I haven't checked fuses or anything. Also I heard when changing the glow plugs its good to try and start the engine when u have them out to get some carbon out of there. I haven't done this before but watched someone do em a little while ago and it didn't look too complex. I'm going to keep the lines on but I figure i'll be ok if i can mannage working inside the door panels. Anything I should look for thanks. I've done a search on the topic

gsxr · #2 12-24-2004, 06:19 PM

If you have your owner's manual, read it carefully. When the glow light on the dash doesn't come on, that *usually* means one or more glow plugs is out. You can then test them with a meter to determine which one is bad, or just replace them all and keep the old good ones as spares. Use Bosch or Beru plugs, not Autolite or Monark. Check the flat 80A fuse in the glow plug relay first, though.

When changing the plugs, it wouldn't hurt to crank the engine over to blow out carbon bits. This shouldn't be necessary if the engine is driven hard regularly and the plugs come out easily. I'm lost about the door panels - all this work is in the engine compartment...

deeph8 · #3 12-24-2004, 06:31 PM

I had the same experience with mine. You can test the plugs by attaching one end of a continuity tester to the proper plug on the relay (search this board) after removing the connector and the other to ground. In my case it was a bad relay. I got a replacement on ebay and that fixed the problem for less than $50.

adiaw83 · #4 12-24-2004, 07:36 PM

Thanks for the tips I'll probably do this in a couple days

P.E.Haiges · #5 12-25-2004, 03:30 PM

adiaw83,

You should check GP with a digital ohmeter because a test light will not detect margianl GP, only open ones. But it is usually the case that the GP will go completely open, so a test light isn't a bad place to start.

Always specify year and model when asking for help.

BTW: Don't look inside the door panels for the GP, they ain't there.

P E H

Jimmy Joe · #6 12-25-2004, 04:29 PM

Quote:

Originally Posted by P.E.Haiges

Always specify year and model when asking for help.

BTW: Don't look inside the door panels for the GP, they ain't there.

P E H

I didn't see them there either last time I looked...
PEH has a good point. Please put your car in your signature, and always geographic location, it really helps the experts to help you.
Thanks in advance for your anticipated cooperation

1stimer · #7 12-26-2004, 03:03 AM

I just dealt with this same problem to get my car ready to move to Washington state from sunny san diego. I've had the car for a couple of years, and don't know when the plugs were last changed. I was able to change all the plugs, but it was a PITA for me. It was my first time, and I did not remove the fuel lines, but it took me about 4 hours. I think I could do it in about 2 hours next time, but I don't want to do it again for a while. After all that it was the relay that was bad. It will save you some time if you just change the bad plug(s). I'm not sure if my ohmmeter isn't sensitive enough or what, but I was getting readings of over 2 on all my plugs which I assumed meant the plugs were bad as I gathered from the forum that specs were .7 or less. In any event it could be your glowplugs or the relay. Do a little more searching for the location and procedeures....test the plugs if you can and ask questions if you need help.

adiaw83 · #8 12-28-2004, 02:06 PM

thanks for the replies. I know where the GPs are I was just saying that I worked in a tight area of the car such as the door panels before and I was comparing that tight area to the tight area in which the glowplugs are located. Sorry for the confusion. I'm in washington, DC and the car is a 1983 300sd I thought that was in my profile thanks.

boneheaddoctor · #9 12-28-2004, 03:19 PM

Quote:

Originally Posted by gsxr

If you have your owner's manual, read it carefully. When the glow light on the dash doesn't come on, that *usually* means one or more glow plugs is out. You can then test them with a meter to determine which one is bad, or just replace them all and keep the old good ones as spares. Use Bosch or Beru plugs, not Autolite or Monark. Check the flat 80A fuse in the glow plug relay first, though.

When changing the plugs, it wouldn't hurt to crank the engine over to blow out carbon bits. This shouldn't be necessary if the engine is driven hard regularly and the plugs come out easily. I'm lost about the door panels - all this work is in the engine compartment...

My case is the all new glow plugs never changed the dash light thing...and I honestly wish I understood why.......but it starts reliably in the cold......I did have a few bad glow plugs before.

franklyspeaking · #10 12-28-2004, 04:31 PM

boneheaddoctor,

Have you checked the bulb? It's a pain to get to....but they don't last forever.

whunter · #11 12-28-2004, 08:12 PM

This thread, it may save you money and time.
http://www.peachparts.com/shopforum/showthread.php?t=104547&highlight=glow+plugs

adiaw83 · #12 01-02-2005, 12:57 AM

I finally did it. It wasn't as bad as i thought it was gonna be just had to be patient. I used a small wrench to get at the bolts holding the wires down to the GPs and a 12 socket to remove the GPs. Everything went pretty well until i got to the final one closest to the cabin of the car. It took me forever to get at becuase I couldnt use the rachet and could get that much rotation with a wrench. I really didnt run into any problems. It took about a good 3 hours so far but I've already put the replacement in for the last glow plug and I don't think the other 4 will be a problem. I also got a brand new 800CCA battery for 15 dollars.