Glow Plug Fuse?? - PeachParts Mercedes-Benz Forum

IZELJIC · #1 02-23-2003, 10:36 PM

After staring at my engine today for about an hour I finally located the glow plug fuse. I just purchased my first diesel (1985 300TD Turbo Wagon) and am trying to locate all the new to me parts. I did not know how the fuse looked until I visited NAPA parts today and they showed me the picture. Mine was missing the black box on the fuse (no fuse) so I think that this might be the reason for my car not starting. Anyway I ordered one and will try to start the car. My question is whether anyone has a nice picture of an engine similar to my car on which they could point out the following:

-glow plug relay and fuse
-glow plugs (any way of testing them without removal?)

Thanks in advance!!

Igor Zeljic (Minneapolis)

diesel don · #2 02-23-2003, 10:46 PM

When you say your fuse was missing and the black box as well. Do you mean the cover to the black box (glo relay box)?

Can you see the two phillips screws where the fuse goes? Is there a cover on that? The assembly should be on the drivers side of the engine compartment slightly forward.

When you put the fuse in, listen for a click when you turn the key to the glo light position. Leave it there for 40 seconds or so and you should hear another click signaling that the glo relay is finished heating.

I don't know how to test the glo plugs. Most guys just replace them all at once since they go out randomly anyway. I just did 5 and it seems to me to run about $15 per plug or so.

I would wait however on the glo plugs. My hunch is that you just need the relay unit to work.

Don

IZELJIC · #3 02-23-2003, 10:55 PM

I appreciate your advice. My cover to the fuse was fine but the fuse itself was just a bar of metal with two philips screws on each side (nothing in between). The picture which I saw today had a small black box on the bar (which I believe is the fuse). So I think that my fuse broke off and the bar remined (since it was screwed on).

I also fixed my vacuum leak yesterday and I am wondering how long does it take to recharge the whole system?

Thanks again, Igor.

IZELJIC · #4 02-23-2003, 11:28 PM

I believe we don't understand each other. After I removed the glow plug fuse cover there was a small bar with two screws. There was nothing on the bar itself. My confusion now is that I saw a picture of a fuse at NAPA and there was a small square on the bar itself (I presume 10mmX10mm). But if I understand you there is nothing supposed to be on the metal bar. My understanding was that if something goes wrong something in the small box on the bar will break (like in the normal fuse) and you have to replace it. But what you are saying is that the bar itself is the fuse. If something goes wrong then does the bar break in the middle?

Aaron · #5 02-23-2003, 11:41 PM

When you remove the cover on the relay, all you SHOULD see is a metal strip fuse. Plain jane simple little piece of metal, no bars or anything like that on it. Go to an MB dealer and have them show you on their parts fiche.

IZELJIC · #6 02-23-2003, 11:58 PM

After turning my key to pre-glow position, after about 30 seconds there is a click in the engine compartment. Does that mean that my glow plugs are done heating. Would that click occur even if the fuse was bad? How can i measure the current on the glows? Do I have to remove them?

Pete Burton · #7 02-24-2003, 12:35 PM

you don't need to remove them, and checking is easy. Follow the wiring harness that connects to the glow plugs back to a flat rectangular connector. Unplug there and turn it over, exposing connectors to view. Use an ohmmeter to check conductivity. One lead on the base of the glow plug (where it screws into the head) and the other on one of the connector terminals (they are numbered). Resistance should be about 1 ohm, as they should each draw about 8-15 amps. If not, problem can be in either wire or glow plug. Make sure you have a really good connection before you condemn the plug.