You're using a ratchet with a spark plug socket?

Maybe you need a longer ratchet if you can't turn it.

As long as you keep the socket on the plug straight, it will not break.

__________________
2012 E350
2006 Callaway SC560

Hey mbzr4ever,

Please let us know how it's going. I have the identical problem as yours.

Mine is a 1990 300E and it runs great but if I don't drive it for about 3 or more days in a row it starts and runs perfectly until it starts to warm up like about 10 minutes or like 5 or 10 kilometers later, it will then stumble and stall. After stalling it will not start, but it will start and run perfectly 1/2 hour or 1 hour later.

It later never misfires or stalls at all, untill by chance I don't drive it for a few days again.

Also in my case I noticed that the fuel pumps don't run when it wont start and I suspect that the OVP Relay is intermitently not supplying power to the MAS control unit which then fails to supply power to the fuel pumps.

There is a lot of info on these potential culprits but testing and tracing the problem withought unecessarily (opps) replacing parts is key.

I'm still in the testing/tracing stage with mine and I will let you know what I find.

good luck and be carefull,
Acky

Acky,

How could you be so lucky as to have the same problem with your 300e? Mine has almost 170K miles, is yours about the same? Does it seem to matter if it rainy/humid?

I hear you, these 300es are quite "sensitive" with all the electronics, which is why I prefer to drive my 240D as the daily driver.

Every post, though, suggested getting new plugs, wires, rotor and coil, if necessary. I was even scolded in this post:

http://www.peachparts.com/shopforum/showpost.php?p=1570884&postcount=9

to expect such replacements as necessary maintenance items. The wires I replaced were bosch, and I cannot tell if they are the original or not without going back through the many years of maintenance records.

The wires, rotor/cap were all easy enough to change. But honestly, I don't notice much difference in how she sounds. Am planning to change the plugs by a mechanic on Friday (appointment is mainly for the front brakes).

That's interesting about the fuel pumps - yes, when it is hard to start, it sounds as if it has run out of gas.

Ok, keep in touch...

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Pretty good for a girl
You did better than me
I whimped out after I did the rotor & cap
I broke a vacumn valve
after that
I put it back together
Figured I'd get help w the wires & plugs.

Took me forever to get them off the cap
finally did get them twisting turning w a pliers
Needed a tool
couldn't get enough strength from my fingers in the tight spot
After I figured it out
wires came off cap fine

They have a boot puller for the wires at plugs
thats good when you want to reuse

I just figured I did enough damage& I couldn't see risking more
for me to install wires that would have to come off to change plugs.

Luckily the broken part was cheap easy fix & might have been defective anyway...

Plugs can get tight esp if its a alum head & if they r installed wo anti seize.
Alum head is softer than the plug metal so overtightening or mistreading can be damaging.

No harm ever came from asking for help...

__________________


83 500 SEC Euro 198K

CamelotShadow,

Did you change the rotor/cap (and wires/plugs) because it was just a maintenance item or were you having specific problems with your engine?

I see you have the 500 SEC, so I'm assuming it was for this car? If it was for a problem, did this change take care of it?

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Yep
only have 1 benz
1st & only benz
thats it

I had a hot hard restart prob
was hoping maybe it would help but
really did it for maint
no real problems just wanting to make it better
think idle smoothed or that could be vac hoses too.

In fact mech saw cap & said its still good
rotor was burnt a bit


Its not humid here

I have heard the plastic covers on top the dis cap
can hold in mpisture & can be sources of problems
not sure if you have that kind?

It can't hurt to have new dis cap & rotor & igniiton wires plugs

My mechaninc changed the aculmulator
he thought thats why it was not starting hot

He may have got it as it started today after sitting 40 minutes
which ordinarlly would take alot of cranking

__________________


83 500 SEC Euro 198K

Are you talking about the black housing suppressor that goes over the cap? Hmmm, I thought as long as the cap was snug (I used slyglide aroung the rim too) it should keep the moisture out?

There is another black cover that goes over everything (wires/distributor) and someone (above) mentioned it was good to have to keep electrical interference away?

I do know that my old suppressor and cap were loose on the bottom, easily allowing moisture into the rotor area.

Glad to hear you have your problem fixed. You are lucky to have a good mechanic to help you along.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Just went over some previous posts - is there supposed to be a gasket between the cap and the rotor?

There is still the coil that could be the culprit.....is that difficult to change?

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Yes, I'm using a ratchet but it probably is not long enough like you suggest.

Anyway, I'm taking the 300 in for the front brakes on Friday, I'm gonna ask the mechanic to change the plugs at the same time. He shouldn't charge me a lot, maybe 15 minutes, max?

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

I don't know your car
but mine has no gasket
I wish I used the dieletric grease as a seal myself on the rim of the dis cap

Mine has no cap on top either

I see the newer models have a cap over the wires
To tell you the truth
don't know how they do that as you got wires coming out all over it

Someone told me that MB has discontinued that design
it caused problems
seems it doesn't stop moisture getting in
but its good at keepin it in too.

I don't know

Its part of your design so you might want to ask around
to see if it is aproblem

They have extensions for the rachet
need about a 4 or 5 on my car

Let them do them
& next time hopefully it will be easier to check them

I hope my guys put dieletric grease in all the boots
I hope thats standard protocol

__________________


83 500 SEC Euro 198K

mbzr4ever, and all,

With my car humidity and/or outside temperature do not seem to be a factor because it has had the problem in winter or summer humid or not. Because I do drive the car regularly, it doesn't break down often. When it does stall out though it is a real pain and potentialy dangerous with cars scrambling and cutting each other off to get around.

If your car is not fixed, and stalls out again, have someone turn the ignition on while you listen at the right rear wheel well. the fuel pumps are under the car just in front of the right rear wheel. Actually do this anytime so you will be familiar with the sound from the pumps. When the ignition is tuned on, the pumps will run for about 2 to 3 seconds then stop.

If your fuel pumps do not run, there is a systematic test procedure to isolate the cause. Please do not replace pumps, relays, control units etc.

Distributor caps, rotors, wires etc do wear and fail over time but they can be inspected and tested. (keep all good old parts as spares).

Yes there is a large rubber "O" ring seal in the distributor area. I'll try to get a pic.

My car has about 180 k kilometers.

Please do not replace the coil just yet.

Do you have a volt meter or multimeter?

Take care all,
Acky

Acky,

Interesting, you say moisture does not seem to be a factor. Maybe I am associating this problem with the rain because it is now the rainy season when it first started acting up?

Because I mentioned rain in the beginning, all subsequent posts/advice/recommendations were based on moisture entering the electrical system somehow...

I used to drive the 300e every day, then I started driving the 240D instead, and sure enough, this is when the problem occurs, when the 300e is not driven DAILY. So now when I know I'm not taking the 300 out that day, I MUST run it (in park) about 15 minutes every day. If I don't, it has a terrible time starting (if at all) the next day.

I agree with you about this being dangerous - what if I am in a busy intersection trying to make a left turn, and it stalls out?

Good point about the fuel pump, will check into that.

Yes, I do have a multi-meter. Gotta go and take the old wires/cap/rotor out of the trash, I threw them out, but like you say, maybe I should test them and keep as spares. Especially, when you live on a rock in the middle of the Pacific Ocean.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Hi All,

I have the same stalling problem. It all started after I washed the engine bay.... It may or may not have been the sole cause, but it didn't have this problem before that, not even once.

When the stalling started, it was almost present every trip out driving. any speed night or day. I got really worried and had the car checked out by a mec who did some extensive testing and still found nothing seriously wrong as far as he can tell. Oh yeah the usual " Your transmission isn't the best and ..."

I drove off and got a Fuel Pump relay from the breakers. Its the only thing that is not expensive and easy to replace by me when it happens again.

So I change it out. It has not happened again. I can't tell if that was the cause. But we could never know. All I know is that I do not want it to happen again. period.

So now its ok. Given the choice again, I would still replace the relay.

Anyway I keep all the old relays in the trunk for spares on the road. They are cheap from the breakers.

Of course I don't keep a spare fuel distributor or Tranny.... hehe don't laugh.

__________________
1992 200E
M102
102.963
AKA Silver Old Grumpy
Always hope I can freeze someone with the aircon- Just change the compressor again, Subseal leaked with a psssssssss sound.
Its the NON-3 Pointed star items on my car that cost more to repair.$%^&%%*^&

You really live in HI?
Lucky you
I grow plumeria
guess you know those weeds

Sounds like maybe its sit related
or jealous


Do keep the old parts
least take pics cap & rotor
did they look burnt?
then u could have wire or plug problems
wires changed so
now whats left.

Its still happening?

It may be more relay or fuel related than iignition

relays can go slow
first could be infrequent
then getting worse n worse

running it everyday seems excessive
it should work with a few days or week sit
My Volvo does & even more than that
same w my old benz
no problem even 10 days
starts in a flash
not so quick on restarts
but I got a new accumulator & its better though not as good as cold start
but still alot better than it was

Stalling is a different thing
could be a failing relay

Had some hard starts
then a few stalls in garage
thern one on the road & I was lucky I got the car coasted safely to the curb wo hitting anything
that was scary
my tail end sticking out in the bike lane
parked at an angle across someones driveway luckily the curbed stopped it just a few feet from a parked car

Don't even want to imagine what would happen on the highway

now you can;t even cold start after a day sit?
sitting a day or so shouldn't matter

By all means see what your mechanic thinks
We can only guess

Good Luck

__________________


83 500 SEC Euro 198K

Everyone,

This sounds very important!!

I was doing a google search on "300e stall" and this website came up:

http://users.adelphia.net/~infoage1/complaints_nhtsa_mercedes_wiring_harness_failures_1991_1996.html

MERCEDES-BENZ 1991-1996 ENGINE WIRING HARNESS DEFECT
NHTSA COMPLAINT SUMMARIES
(last update 04/18/2007 to 302 complaints)

Apparently, this is a big problem that MB corporate refuses to recall. Something about the engine/fuel injection harness deteriorating, causing shorting, fire hazards, etc.

Maybe everyone knows this already? Probably needs (or already has) its own thread.

edit: here is the info:

http://www.peachparts.com/shopforum/showthread.php?t=166883

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K