hi guys,

its my first post, hopefully my later posts will be not with the car stuck in the garage!

up until this morning, the glow plug indicator was working great -- however, when i tried to start it at lunch, the indicator wouldn't heat up no matter how long i held the Engine Knob on for. the engine would just crank over and over.

my question is: what is a good place to start looking to diagnose the problem? Do you think it is a fuse? it was starting and running fine up until this time.

any help would be appreciated. If it is a fuse, where would it be? and what is the specs?

thanks!

tyler

There are great threads in the archives on this diagnostic procedure... that would be much faster than waiting for people to show up and fill out all the details on this subject...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

oh ok cool! i didn't know where to look, i just signed up.

While you're searching, be aware that there are two main types of glowplug setups in Mercedes diesels. The loop style, which you have, are wired in series, so if one fails, none of them will work. Much of the troubleshooting that's been covered here applies more to the pencil style (came out around 1979) in which the plugs are wired in parallel. On that setup, you can have one or more plugs fail while the rest still work. The troubleshooting for the two systems is therefore slightly different.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

its a 1975, i dont think the plugs have been retrofitted -- i know there are 4 spares in the driver's side door pocket though.

The early style plugs have a pattern the squiggly wires have to be put on in, that may be slightly out of whack if someone replaced the plugs and didn't remember how they fit and got it wrong when they put them back on. I have also experienced problems where the last connection that goes to ground, has been broken and when that happens the plugs all don't get energized. I don't recall exactly - it has been more than twenty years - but I think the last connection is potentially fatigued by engine rocking motions, and eventually the wire just breaks - inside the insulation at times.

I am on travel and cannot scan the page that shows the connection scheme, but keep in mind the glow plug body threads that screw into the head don't ground the connections - there are coaxial plus and minus connections on the connection pins of the plugs and balancing resistances in the squiggly wires that connect them. If you are testing the system be forewarned the squiggly wires get hot.

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

You might want to look here:

http://www.peachparts.com/shopforum/diesel-discussion/137732-glow-plugs-link-thread.html#post1019018

When troubleshooting it is best to have a Volt/Ohm Meter (Multimeter).
On the system you have when 1 Glow Plug develops an open circuit (like if the Heater Element Loop burned) they will all stop working because they are all part of the same series circuit.
Before disconnecting anything take some good digital pics or draw some pictues of the setup so you can put everthing back the way it was assembled.
Pay particular attention to where the wires connect in relation to the Retaining nut and the Insulator on each Glow Plug.
Also you will have a small Ground Strap on one end that will ground to the Cylinder Head or connect to a Temperature Switch/Sensor.

The first thing is the verify what is actually getting Voltage and what is not.
Start at the Glow Plug nearest the Fire Wall and work your way forward and see if each Glow Plug is getting Voltage.

Some systems have a Strip Fuse in a plastic Box on the Fire Wall (trace the Glow Plug Wires back) or there is a built in Reed Switch inside of the Relay Box that acts as a Fuse.

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84 300D, 82 Volvo 244Gl Diesel

damn you loop system! i did notice a slight "buzzing" noise coming from the engine compartment (sounded like something electrical) a couple days ago -- it went away, but so too did the starting...

is the heater element loop the thing inside the cab? it is a black circle, directly behind the steering wheel, which turns bright orange when you pull on the engine knob? -- i just got the car a couple weeks ago, still learning the extreme basics!

I think most poster are assuming the OP has a loop relay system activated by the key. From his description, I think he has the older loop gorilla knob system without a relay activated by the key. In that case I'm not sure there is a fuse in the system. The most likely cause is simply a single bad glowplug which will cause the rest of the glowplugs to fail since they are wired in a series. There is an input wire and an output wire on each glowplug separated by a porcelain insulator. Putting an ohmeter across those wires at each plug will tell you which one(s) is bad. You should get continuity thru the plug. If you don't, you know that plug is bad. Once you find the bad plug(s), replace it. For a temporary fix, jump the plug with a heavy wire, connecting the input and output wires. Then the rest of the plugs will work.
Testing his system for voltage will require two people since someone will have to pull on the gorilla knob.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

No. I think most people call that the 'salt shaker'. (I don't know why) but it's just an indicator light to tell you that the loops at the end of the glow plugs are functioning. When that stops glowing orange, the loops have stopped glowing also.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I assumed it required one person and one gorilla.

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Have you considered going to the new style GPs, you wont regret it if you plan to keep the car.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

i will upgrade to the newer style GP's once i get the car back to my house! its currently stuck at the garage at work!

Soo, no relay in the 1975 models -- shoot, i was hoping for an easy reset fix. Why do none of the GP's work if one goes out? Are they like those christmas lights on strands from the 1950s?

i really hope its just a glow plug issue!

thanks,

tyler