1979 300SD Turbo Diesel Not starting .. BUT!?! HELP - Page 2 - PeachParts Mercedes-Benz Forum

kerry · #16 11-29-2011, 09:54 PM

They are on the left side of the engine block under the injection lines and above the injection pump. (left as seated in the driver's seat--that is the standard protocol for right and left on a car)

vstech · #17 11-29-2011, 10:03 PM

www.dieselgiant.com
this will both show you where the glow plugs are, and explain an easy way to help narrow down the bad glow plugs.
My recommendation is to just pull all 5 plugs, and install a fresh set of BOSCH 80006 glow plugs.

kerry · #18 11-29-2011, 10:10 PM

It could also be a bad strip fuse which is in the glow plug relay mounted on the left inner fender.

vstech · #19 11-29-2011, 10:15 PM

I wasn't sure where the glow relay would be on a 79 116...

79Mercy · #20 11-29-2011, 10:51 PM

a 79 SD has the GP relay on the front driver side fender well. It looks a bit different then the W123 and W126 style relay

For future reference, all TURBODIESEL's have pencil glowplugs, none of them had loop plugs.

vstech · #21 11-29-2011, 10:59 PM

is it the same monster controller the 80 123 series used? (my parts car had one in it, and it was a bit larger than the newer ones.

79Mercy · #22 11-29-2011, 11:18 PM

nope, its different than that. The 1977-1980 w123's had a silver box GP relay under the dash

vstech · #23 11-29-2011, 11:22 PM

nope, the late 79 to 80 123's have pencil plugs, and a large plastic relay on the fender...

kerry · #24 11-29-2011, 11:28 PM

Quote:

Originally Posted by 79Mercy

a 79 SD has the GP relay on the front driver side fender well. It looks a bit different then the W123 and W126 style relay

For future reference, all TURBODIESEL's have pencil glowplugs, none of them had loop plugs.

Yeah, that's right. I missed the 'turbodiesel' part in the first post and only saw 1979.

barry123400 · #25 11-30-2011, 12:02 AM

Quote:

Originally Posted by RicciRicci

"You probably have old style loop glow plugs. Do you know the difference between loop style plugs and pencil style plugs? If so, tell us which ones you have. If you don't know, do you have heavy squiggly wires going between the glow plugs?

From your description I assume you mean that the engine is turning over but is not firing. Is that correct?

"

Yes, you are correct. My feelings were related to the GLOW PLUGS as well, but I wondered how seriously they could be effecting the car. I live in San Diego and its my understanding that in a diesel engine, the ONLY thing the spark plug is generally used for is getting the cylinder warm enough for the compressed air to ignite the fuel. IF the glow plugs are the issue, and they are used for more than "warming" and are actually important for igniting the fuel, I'll make sure to fully investigate the glow plugs ASAP.

My thoughts are that this is NOT glow plug related and I'm FAR from a mechanic. My reasons are I'm in a warm climate. PLUS, if I let the car run for about 3 minutes, turn it off, wait about 10 minutes (engine is still warm) the car turns right over. The fact that "thinning" the air with a combustible air product leads to it turning over seems more like I'm having fuel or air mix issues and NOT glow plugs.

I'll check the plugs. There are a few good posts that describe how to do that. I just fail to see how, in this case, the plugs are the answer.[/QUOTE]

A lot of diesels will just not start without some glow plug assistance hot or cold. You are probably not doing your starter and battery much good if the glow plugs are out either.

On some engines even a couple of duds are enough to basically disable the starting. If you have the series plugs with the squiggly wires one bad is way too many. As all the rest will be non functional even if good.

When you put the ignition key in the glow position the internal cabin light should normally dim reflecting the heavy load if there. No dimming equals no glow plugs working. Do this with the engine cold though. The test is not rocket science either.