The glow plug light on my 1977 240D has failed to come on two times now. Once, two weeks ago and this past Friday. On Friday, I turned the key three times with a one minute space and no light. Tried cranking it the first time in case it was the bulb--no go. Waited five minutes and it the light came on and the car started.

Any ideas--Should I replace the glow plugs or would that just be throwing money at the problem?

By the way. Drove the car from Austin, TX to Orlando, Fl leaving last Wednesday night. 22 hours, 1187 miles, 27.85 MPG

Thanks

__________________
Anders

1995 E300
2015 VW TDI Sportwagen 15K
1977 240D (197K)
2002 Subaru Legacy L Wagon (115k) (Wife's)
Gone but not forgotten:
2005 Buick LeSabre
1998 C230
1984 300D
1983 240D
1981 300SD
1974 240D
1974 Fiat 124 Spider
1968 Triumph TR250

Any Ideas?

__________________
Anders

1995 E300
2015 VW TDI Sportwagen 15K
1977 240D (197K)
2002 Subaru Legacy L Wagon (115k) (Wife's)
Gone but not forgotten:
2005 Buick LeSabre
1998 C230
1984 300D
1983 240D
1981 300SD
1974 240D
1974 Fiat 124 Spider
1968 Triumph TR250

First check the inline bar fuse on the hotwire at the firewall. If it's roasted, then piece of wire or cut up soda can will substitute.

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'80 300SD/ w116
'79 240D 4-spd
'71 750cc Guzzi

previously owned:

'83 240D 4-spd
'77 280SEL 4-spd
'74 280/8
'72 250/8
'65 220Sb 4-spd
'63 220Sb 4-spd
'63 190c 4-spd
'61 220Sb 4-spd
'60 190b 4-spd

240DieselDog,

Thanks! I checked out the inline bar fuse and it was fine. Back to the drawing board.

__________________
Anders

1995 E300
2015 VW TDI Sportwagen 15K
1977 240D (197K)
2002 Subaru Legacy L Wagon (115k) (Wife's)
Gone but not forgotten:
2005 Buick LeSabre
1998 C230
1984 300D
1983 240D
1981 300SD
1974 240D
1974 Fiat 124 Spider
1968 Triumph TR250

Then pull the glow plugs starting with #4, first on the circuit. Loop style plugs can burn out - easily detected with visual inspection. The only trick is lining up the heavy guage wire exactly as it was, alternating between upper and lower contact points.

Scorched my own #4 GP once and it disabled the entire system causing a zero GP light situation.

If you find a burned out plug but have no replacement, relocate it to #1 cylinder and the other 3 should heat up.

after moving it and get by that way??

Don't ask me how I know you can make toast under the hood if you hook all the resistance wires up to the outer contacts. the engine doesn't start very quickly that way either....

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Jim

'49 170?(donated to church in Darmstadt '58)
'58 220S(crusher, after '73 fire[San Antonio])
'72 280SE 4.5
'77 240D
'81 300SD
'83 240D parts car

You have series glow plugs so basically they are most likely okay. Sounds like the relay does no longer reliabily turn on. In just my opinion would try another relay first. Could be an oxidized connection or even a failing key switch as well though but again the old tired relay would be a suspect first. One other thing I should mention is once in awhile one of my cars the 77 300d does exactly the same thing. I just turn key on and off a couple of times till light comes on. I have never troubleshot this problem but if car was in daily use would always keep a jumper in trunk so in the event of total failure would bridge positive battery terminal to top of glow plug chain to get vehicle started. The older relays are not in demand as much as the newer style for parellel plugs so a junk yard replacement is a possibility. A search of the archives is in order as well as the problem is pretty common I think. (intermittent glow plug function) (the relay is located above drivers feet is silver in colour and has a machine screw and nut to fasten it to pedal bracket support if you do not have location information as unlike the newer and different ones it is not in plain sight. I only threw this in as your service information may be limited)

hey dude well it might sound dumb to some people but i had a glow plug light problem on a 240D before and i thought it was the ignition switch but it was not! it was the Battery!!! i changed the weak battery and now the light comes on! MB told me if MB diesel's have a the wrong battery in or a battery that was short circuited the glow plug light will fail but you still can crank it! weird huh? well i learn something new everyday check your battery man! check your key switch, GP relay, fuse on the fire wall and the wiring. ill say it again it happend too on my w123 300D to!! i had to change the battery because the GP light would not come on! weird huh but it was true for my car and my custumers car! cya....

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1991 560SEL AMG "Jap spec"
1989 560SEL Euro spec

MBdiesel Freak,

What do they mean by the wrong battery? A 6 volt or 24 volt battery? I don't believe the electrical system will know the difference in any 12 volt battery as long as it has enough current capacity.

GP lights are known for being intermittant. Yours will probably not work again and then U can try the tests.

P E H