I've done hours of reaseach before posting this thread, but I still need some advice.

Here's the symptoms...

turn key to on
no glow plug indicator light
auxillary fan in front of radiator comes on (does not normally come on but always coincides with this problem)

turn key to start
starter engages normally but no engine fire

I can get the car to fire normally after turning the key on/off for several times. I know the engine will fire even before I turn the key to start because the glow plug light will come on/off normally and the aux. fan will not be on while the ignition switch is in the on position. No additional problems after car has started.

The first time I had this problem was after I let the car sit for a week while I was out of town. The problem was intermittant for the first two days and then then the car started fine from that point on. Then I went out of town for two weeks. Got back yesterday and the same problem again when I tried starting for the first time. Now the car seems to be doing ok.
I can have the symptoms when the car is cold or hot.

I have a few theories I would like to run by you...

Bad temperature switch or sender causing the aux. fan to come on and the glow plug light not to illuminate and the car not to start?

Bad iginition switch?

Is there an OVP relay on a diesel that may be bad?

Bad fuel shutoff valve? Where is it located? How to check its operation? Why would that make the aux. fan come on when the key is on (car not running) and the car is cold.

I don't think it's a bad neutral switch because the engine always turns over ok. It's just an intermittant starting/firing problem.

Hope you guys can shed some light on this. I'm taking a gamble in the morning and driving to my mom's for T'giving.

Neil Eaton

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

neil, when you are cranking the engine, does the red and green lights on the inside rear mirror alternately flash?
Ray
mercedessd@cox.net

I have not noticed the lights blinking so I don't think they are. I'll try to specifically look for this in the future.

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

Did you try another key? I had some problems with start up and it turned out to be a dying infrared key.

In the 97 you can use the spare, non infrared key if you need to and want to avoid the $200!!!!!!!!!!! replacement.

if they do it is an indication of no drive authorization being sent. please let me know your findings. i agree with the previous post.
Ray
mercedessd@cox.net

Interesting.

I have two infrared keys and couple of keys w/out the infrared contraption. But the infrared only operates door locks (right?).

Are you saying that I should lock / unlock my door w/a key that does not have the infrared contraption and then try starting the car?

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

Car is giving the same non-starting symptoms tonight.

I tried another infrared door opener, but still had the same problems. Locked / unlocked several times.

I did notice the following:

1) The red and green lights did not flash while I was cranking.


2) It takes about 5-seconds before the aux. fan comes on after turning the key to the on position (I'm going to double-check whether this is normal next time the car starts normally)

Thanks for your ideas.

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

Confirmed.

After repeatedly turning the key on / off, I got the car to go thru a normal startup (i.e., glow plug indicator light on / off and the aux. fan did NOT come on at all while the key was in the on position, car then started and ran fine)

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

Hey carson356,

Referring to your above quotes on 11-24-2004, 06:00 PM, what are the rectifications to this problem? I am having the exact @#$% problem for the last 10 months now. It has been occurring to me intermittently. The red and green lights flashes alternately and only cranking, able to start up again after 5-10 mins like nothing had happened.

I have purchased and replaced:
ECU/HFM
Car Key
Car Battery
Voltage Regulator
IFZ Control Module
IFZ Control Module & Car Key (under warranty)
OVP Relay


Still these did not solve the problem. I hope you can give some ideas on what could also be the cause of this problem.

Thanks!

I had a similar problem on my '97. The dealer told me the car has an anti-theft device that prevents fuel from flowing to the engine if the car doesn't recognize the key being used. I guess it's supposed to stop people from being able to "hot wire" the car but sometimes it backfires because it won't even recognize the proper key. Mine only did it twice so I never bothered to have it looked at but I did ask a mechanic at the dealership and that's what he said the problem most likely was.

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

I don't think they offered the "smart key" until 1998.

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

I think there must be some smarts in the 97 key. I have one bum button key , one good button key and two manual keys. All but the bum key start and operate the car.

Thanks guys,

Don't you think it is embarrasing with a prestige of having a MB vehicle to cause this kind of intermittent fault?

SCott98, your dealer did say it was other caused besides "backfiring"? By the way, what model is yours? I'm driving a 95 C280

Maybe using "backfire" was a poor choice of words. I meant that the idea of using a smart key to prevent auto thefts "backfired" on Mercedes because the system doesn't always work and then the owner with the key can't even start the car.

The car I had was a '97 E300 but now I just have an '85 300D.

Scott

__________________
Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)