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  #1  
Old 03-05-2003, 08:33 PM
DieselHead's Avatar
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Location: Manhattan; Shelter Island
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My strange glow plugs...

The glow plug problem continues. I cleaned the contacts on the relay and changed the fuse and the glow plugs worked just great. This afternoon they refused to work BUT they worked in the morning. I noticed that they will always work when the car is still warm, and I noticed that I didn't have any problems for the past week or so when the weather was dry. I just went out to use the car a few minutes ago and the plugs didn't work. Car was cold and it is damp out from the rain today. Any connections you guys can make? Oh, my mechanic tested the plugs themselves and said they were fine. This only leaves the relay or the wiring, which I think is also fine. Oh, and I have a voltimeter wired into my electrical system so I know the plugs aren't working because there isn't the usual 2V drop.

Also, I was planning on taking this car skiing friday for a day trip and don't really want to get caught if my plugs don't work. How would I go about connecting the plugs directly to the battery as some have done? What are the proper connection points? I don't want to screw it up, fry the plugs and destroy the battery.

Thanks so much! Sorry to bother you with another GP issue.

Alex

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside
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  #2  
Old 03-05-2003, 09:07 PM
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Location: Woolwich, Maine
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Alex,

When they don't work, do you try a few times and they still don't work, or just once or twice? Are there any other electrically operated anomalies?

The whole process starts in the fuse box and goes to the light switch and then to the key, I believe. I would start by cleaning off the fuse box connections as they are spring loaded and as they get crudded up, cooler, damper weather will make the connection there most susceptible to intermittent operation.

Since the light switch and starter switch are pretty much inside the car and protected, you might check some of those outside connections again. On my old 220D, when it was pretty new (< 2 years old) we took it to Aspen, Colorado on a skiing trip. The car became impossible to start unless we pushed it and I was getting no glow plug resonse. Turns out the wire to the plugs broke inside the insulating sleeve to the eye type connector and while it looked ok, it was not ok. I found it by yanking on the various electrical wires. The bad one broke off in the cold, I fixed it and everything was fine for about 20 years.

Your next bet is the light switch and next the starter switch. I believe the power to the starting switch, operated by the key, comes from the light switch. Over time, these connections can get worn and unreliable and the wires themselves can fatigue from becoming embrittled (usually due to getting pretty hot from use) and the typical Diesel vibration. In colder weather they can make poor or no contact, become more susceptible to fatigue, and moisture just adds to the problem (fatigue cracks become corrosion sites). Either switch can be at fault, as can the wires themselves, especially where they enter the connectors.

Good luck and I hope this helps. Jim
__________________
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)
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  #3  
Old 03-05-2003, 09:23 PM
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Jim,
Ok, I'll go look at the main fuse box now. I thought the glow plugs and the relay were complete separate from those small plastic fuses. No other electrical problems at all. JUST the glow plugs. I'll it out and report back in an hour or two.

Alex
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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside
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  #4  
Old 03-05-2003, 10:17 PM
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Location: Woolwich, Maine
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Alex,

After reading your response, I went to consult my manuals. You may be correct in the belief that there is no fuse in the power supply from the battery to the glow plugs, and the relay operating circuit.

I only have detailed schematics for older 220D types, and they had that actual glow plug on the dash above the steering wheel, which did not involve a relay. But power from the battery gets to the light switch and from there to the key operated start/run system, without passing through a fuse of any kind.

I have a crude schematic for the early W123 models from a manual for the 1974-76 240D with a supplemental section on the W123. This schematic shows the power to the glow plugs themselves coming from the plus side of the battery and going through the light switch (terminal 30) to the glow plug relay, while the power to activate the relay comes from the light switch (also terminal 30) and goes to the key operated starter/preglow switch. This implies there is no fuse in the supply line to the light switch on these models as well. I am having a hard time believing MB would provide a hot wire to the interior of the car without a fuse but it appears they have been doing it for a while.

If you have a later model some of the details of the relay change, but I am fairly certain the power for the plugs and the control of the relay runs the same route. If you need it I can scan and post the schematic.

There is a fuse (50 A) for the glow plugs themselves, and it is mounted on the firewall on the early W123s (on the front left - driver's - side inner fender on later ones).

Sorry if my first discussion was bum dope. Good luck, Jim
__________________
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)
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  #5  
Old 03-05-2003, 10:32 PM
fz500sel's Avatar
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Join Date: Nov 1999
Location: Venice, FL - "sharktooth capital of the world"
Posts: 712
Not to get off the subject but...

I was just wondering (excuse my ignorance) but if you have a diesel with an automatic transmission and the glow plugs are having a problem, can you still get it started by pushing the car and then popping the clutch?
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Frank
84 500SEL EURO 101K ( JUST LIKE MY 1ST WIFE. GLAD TO GET RID OF HER! )
85 300D 310K (sold)
90 350SDL 184K sold
83 300D 118K (sold)
88 300E 153k (sold)
93 400E 105K (sold)
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  #6  
Old 03-05-2003, 10:44 PM
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Location: Woolwich, Maine
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FrankieZ,

Well, you cannot "pop" the clutch because there isn't one to "pop" but you can tow the an automatic in neutral up to about 35 mph, then, with the key in the run position, put it in drive and it will start as if it had a clutch to pop. I believe the specifics are in the opeator's/owner's manual. Jim
__________________
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)
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  #7  
Old 03-05-2003, 11:04 PM
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Jim,
Thanks for the detailed response, and thanks for taking the time to consult your manuals. So I think that what you're saying is that I should check the ignition and headlight switches. Nuts. Sounds like work.

Alex
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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside
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  #8  
Old 03-06-2003, 12:07 AM
fz500sel's Avatar
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Join Date: Nov 1999
Location: Venice, FL - "sharktooth capital of the world"
Posts: 712
no connection between brain and fingers

Jim,

What an idiot I must've seemed like. I was talking about a manual tranny but my fingers typed automatic tranny.

So I assume with a manual tranny you can "pop" the clutch and it will crank!
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Frank
84 500SEL EURO 101K ( JUST LIKE MY 1ST WIFE. GLAD TO GET RID OF HER! )
85 300D 310K (sold)
90 350SDL 184K sold
83 300D 118K (sold)
88 300E 153k (sold)
93 400E 105K (sold)
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  #9  
Old 03-06-2003, 01:12 AM
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Location: Woolwich, Maine
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Alex,

If the connections under the hood to the glow plugs and relay, which you have already checked once recently are still good, then the only ones left are the light switch and the key start/glow switch. I would look at the stuff under the hood carefully and make sure there are no cracked or damaged wires that make intermittent contact. Stuff inside the insulation at or near the crimps to the connectors is where I would focus my attention for the moment.

FrankieZ,

Yes, the most reliable way to start one of these in dead of Winter is to pop the clutch. My daughter learned to park hers facing down hill when the starter was shot. She could start the car in less than a car length on a warm day. Good luck, Jim
__________________
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)
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  #10  
Old 03-06-2003, 04:30 AM
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Location: San Jose, CA
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I have found more success with using second gear, rather than first. Sometimes in first, the wheels just skid rather than turning the engine.
Oh, and don't forget to put in the clutch when the engine starts, and rev it a little.
Oh, and don't forget to turn on the key to ignition first either!
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1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
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"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"
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  #11  
Old 03-06-2003, 08:01 AM
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alex - i assume you took off the cover of the relay and checked that big fuse inside- correct?
if you need a relay i have a spare.
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1984 300D Turbo - 231k....totalled 11/30/07 RIP
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  #12  
Old 03-06-2003, 08:31 AM
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I might take you up on that relay offer. Where are you located in CT? I'm in lower westchester now and through sunday I think. Thank. ALso, how much are you looking to get for it.

Alex

EDIT: Oh, and yes, I have replaced the large fuse. After I replaced that fuse it worked great for a whole week. No it's back to only working 4 out of 5 times.
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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

Last edited by DieselHead; 03-06-2003 at 08:43 AM.
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  #13  
Old 03-06-2003, 08:47 AM
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alex - i am in very south western part of ct. i was thinking you could try out my relay to see if yours is bad cause they cost about
140 bucks or so from the dealer if i remember correctly.

that way you would know if you need one or not. no sense in paying for a new one just to test it.
what do you think? we are not that far away from each other..
bob in ct

edit: just saw your edit - looks very much like the relay itself is bad. lemme know what you want to do.
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1984 300D Turbo - 231k....totalled 11/30/07 RIP
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  #14  
Old 03-06-2003, 08:52 AM
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The problem with trying before buying is that my problem doesn't always occur. The measure of success would be going over a week without incident I think. I don't know if it would be fair to hold on to your relay for a week without paying for it. Is there a way I could come by today late afternoon? I don't know if I mentioned that I was planning on going skiing for the day tomorrow and even if I can't install it today, it'd be good to have in the trunk with the tools that I would need to install it in an emergency. Thanks!

Alex
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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside
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  #15  
Old 03-06-2003, 08:57 AM
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yes fully agree you are welcome to 'borrow' it for a while to see if that indeed is the problem- they are a piece of cake to install - take you 5 minutes tops.
i am here all day - but its snowing like mad out...

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