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190E, SLK350
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Discussion Starter #1
I am not sure if a 2.3 distributor cap (ignition) needs an O ring but I suppose it should since my car never starts when it's damp outside.
I never had one nor gotten one when I ordered new caps and rotors throughout the years.
I looked online, but I suspect the ones I see are for the 2.6L and not the 2.3.
Can anyone confirm its existance, and if so, what is the part number?
 

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1989 W124 260E
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1,256 Posts
The only seal i know of is the one on the plastic type shield at the rear of the distributor . You need to remove the rotor arm drive to get to it easy job once you have the distributor cao and rotor off.
Close up of bracket-adapter for rotor in the distrubitor(with red arrow and text).jpg
51io4qaYMML._AC_SL1000_.jpg
 

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1989 W124 260E
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1,256 Posts
I have never seen on on any cap . The gap from cap to rotor needs to be correct if seal perished the rotor will not have the right clearance .Wish poster had said he had the points system distributor .
 

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190E, SLK350
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Discussion Starter #6
My problem is that the car doesn't not want to start on damp days. I have already replaced the coil and the battery as regular maintenance anyway.
Maybe I have moisture in the gas...
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,500 Posts
Does it have what is call a suppressor plate (the orange thingy on a 2.6)?
I have read somewhere, that is more important then the o-ring for humidity
Is there anything there that can stop the arching to the body from the rotor to the chassis?

Again I have not ever seen a 2.3 distributor so just guessing here.
 

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190E, SLK350
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66,974 Posts
Discussion Starter #8
You mean the orange plate as shown in the first picture by plinker? No, mine doesn't have that!
It has a dust shield right under the rotor, it's black and domed shaped.
The cap is screw in without an O ring or gasket of any sort.
At the bottom of the distributor mechanism (you have to take the whole assembly out to see this) are three holes. I am guessing they're there to equalize pressure or for some sorts of breathing.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,500 Posts
That "dust cap" is what also isolates the rotor from the chasis. Make sure it is not compromised (cracks in it).
I do not know what your distributor looks like but please check that black thingy and maybe post a picture.
 

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190E, SLK350
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Discussion Starter #10
I got a whole new assembly in the mail today. Same dust cap!
Installed everything, made sure the camshaft line matched the line on the distributor and that the balance wheel was lined up to TDC.
Car will not start. It turns over but will not start.
Battery full
All spark wires have continuity, including to the coil
Gasoline reached the fuel distributor and pressure (using gage) is good.

Only problem: Humidity and damp air. This has always been a problem for the last 5 years :( the car will not start if left for more than a day in a damp environment. It's probably time to toss this car down a ravine.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,500 Posts
And the rotor is pointing near the #1 cylinder spark plug correct?
That Dust cap is a very important isolation barrier when the air/distributor is damp as the water can not go thru it and cause the spark to "jump".

Hopefully you have a 12 dollar strobe/timing light. You need it now.
Have someone crank the car and see if the timing is around 20 degree BTDC as you are cranking.

- Good luck
 

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190E, SLK350
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Discussion Starter #12
Yes #1
I have a strobe light... if I could just get the engine to start.
My problem is humidity!!!!
I bet it will start just fine on a dry day. I will have to wait but my problem isn't solved.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,500 Posts
You do not need it to start, just crank and use the strobe light, make sure you have not over looked something.
A bosch remote started available at any auto store is your friend if you do not have a helper.

Helped me a lot when I had an ignition problem and could not start the car.

How is that suppressor (dust cover) is looking. Any burn marks on it?
They are visible on the orange suppressor for the M103's. Not sure about your black one.
 

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190E, SLK350
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Discussion Starter #14
It's still a matter of humidity I think. I just can't pinpoint how and what the humidity is preventing the car from stating. The cap, wires and coil are all dry.
 

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190E, SLK350
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Discussion Starter #15
This morning: Weather condition = dry
Car started right up, on the first twist of the key.
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,500 Posts
Yes that plastic black cover is for humid air mostly. The Distributor is not fully sealed as you have witnessed. Basically you are looking for components that are not sealed and the gaps in ultra high voltage components arc during wet conditions.

Not sure if that would be an issue with an old coil. How old is yours?
 

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190E, SLK350
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Discussion Starter #17
The coil is brand new, I installed it a couple of months ago.
 

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If humidity getting under the distr cap is the problem then you should be able to remove it, blot the underside well, and quickly reinstall and start the car. The distr cap isn't perfectly sealed. I've been overzealous with the pressure washer and caused a misfire or no-start on M102 and other motors on multiple occasions. Popping the cap shows water intrusion. Dry it off and back to normal.
 

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190E, SLK350
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Discussion Starter #19
I had cleaned and dried the cap yesterday while the weather was humid. It didn't work!
The problem is elsewhere. I am thinking either the altitude sensor or the ignition module that's against the interior of the engine bay body. The latter could be the problem if it doesn't drive the coil because of some short. I will have to figure out a diagnosis to confirm that. EZL I think...
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,500 Posts
PN187 just reminded me. When my car was young (like myself :)-)) I liked a clean engine and would power wash it every other year or so.
This happened for maybe a half a dozen times. I was never careful, just sprayed the whole engine liberally. Never did I have trouble restarting it except that last time perhaps 16 years ago in which there was a lot of steam and the car may have started and died pretty quickly. I had to wait 15 minutes with an open hood for it to restart.

Needless to say I never power washed the engine again.

The point I'm trying to make is that when everything is sealed properly and for a M103, humidity is hardly an issue it seems.
It's when these cars, electronic components, seals/etc are starting to age, these issues may crop up.

The EZL as far as I can see is a sealed component but who knows there could be some issues there like cracks on the casing, broken seals, etc.

Sounds like putting the hair dryer on selective components one at a time when the engine refuses to start is probably a reasonable path at this point.
Process of elimination with the hairdryer is in order it seems.....
 
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