Christy:
Now this is really confusing. As far as I know there are only a possibility of two ignition systems on the 250C. Type 1 which has a short brown wire from the negative post on the coil to a ground on the fender well and Type 2 which has a black wire running from this same post on the coil to the Transistor Controlled Trigger Unit (behind the grill on the drivers side and under the battery). None of these ignition types has a direct connect from coil to distributor. This wire could/would be present in a non-transistorized points system. In our cars, the stock ignitions had the Control Unit that actually fired the distributor. If you have no wires running from the control unit to the distributor (except for a ground wire - I think it is black) then the control unit is wired out of your system. If not, there should be a green (I think) wire from the control unit to the distributor where the condensor connects. You might have to pull the battery to check. Be aware also that the control unit has a grounding strip on it so if you have wires from the distributor to this unit verify that they are either to the unit (plugin module) or to the ground strip. If they only go to the ground strip then they would/should not effect in the ignition system.

If you system is re-wired (due to control unit failure) then this wire and connection will need to be clean and tight as that wire completes the circuit from coil to distributor.

Hope this helps rather than muddies....

Dan

__________________
Dan Taylor/ Tulsa, OK MBCA
'84 300D/'90 Jaguar XJ6/XJ40

Hi guys...
I took the wire to the Mercedes dealership. The guy there didn't believe it was original to the car. My ignition coil has 2 small wires on either side of the LARGE center wire. One small wire goes to the area under the fuse box, and the other wire (my broken one)goes to the side of the distributor. There IS another wire on the side of the distributor, on the same bolt, that travels UNDER the distributor.

I replaced the wire.

Interesting thing happened...I FORGOT that I had disconnected the fuel lines, to have better access to the side of the distributor. Well, when I got the wire on, I CRANKED the engine and IT WAS SO LOUD AND STRONG....SOON I realized that I had not connected the fuel lines, as I saw gas spewing everywhere...BUT the interesting thing is this: the car came as close to starting AS EVER, with the fuel lines OFF.
What the heck does THAT mean????

I am still not certain of the importance (if any) of the wire. It's supposed to be a low tension wire? I don't think my ignition coil is the transitor type.

Now I'm back to the FUEL problem...possibly TOO much.

The mercedes guy AGREED with Bill Streep about the gas in the crankcase (in the oil). He said HE'D still try to start it, then drain that oil later.

AND..sorry Chuck!! I am monopolizing YOUR thread!!

~Christy

Sorry folks. I hadn't realized that the car has or had an electronic ignition... my 250S didn't, and the wiring diagrams I have are for non-electronic ignition. Oh well...

__________________
Bill Streep
San Antonio
'57 190SL (toy)
'08 S5500 (mine)
'09 CLK550 (wife's)
'06 SLK350 (daughter's)
'11 GLK350 (daughter's)
'03 CLK310 (spare)

Hey guys...

What's a CONDENSER?? I noticed that they are REPLACABLE..
Should I replace mine?????? My distributor looks pretty corroded....hhhhhmmmmmmmmm....

~Christy

A condenser in the auto world is a capacitor to the electrical engineers.

There are TWO reasons to have a condenser in your ignition system. 1- It plus the balast resistor and the coil make up the charging circuit. 2- It helps suppress the noise from the ignition that shows up on the radio.

I'll read the earlier posts Sunday AM to help sort out your ignition problems. The short answer, is that if you DON'T have any sort of special ignition box and only have a balast resistor and a BLACK coil, then you also need a condensor. If you ignition has some sort of transistorized box added to it, then you DON'T need a condensor for the ignition, just noise suppression, so it's optional.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

CTH...

MORE importantly, my car came as close as ever to starting, with the fuel lines OFF the carburetors.

THIS makes me think that I have a TOO MUCH fuel problem.

I'm trying to figure out some possible causes.........
Needle inlet valves??? Accelerator pump????

~Christy

I'm awake now...

OK. Ignitions systems....

As of 1970 or so model cars, there is a switch-over from conventional ignition systems to a transistorized one.

Question 1, your distributor should have a number on the side. Which of the following (if any) is it?

0 231 116 048
0 231 116 052
0 231 142 003

The wiring pattern of the ignition system helps identify which one you have. That, and the color of the ignition coil.

You have two choices of bosch coils. One is black, the othe blue. The difference, is that the blue coil has about 50% more windings in it and produce a hotter spark ONLY if it is paired with the transistorized switching unit. If not, all it does is blow your points really fast.

The switching unit is a grey metal box, about the size of a couple of paperback books. There are 4 variations to the switching unit. But in 70/71, there were exactly 2 possible (the others came later). They have heat sink fins on the box. It's easy to spot, IF it's actually there. On a 114 chassis car, it's bolted to the inner fender-well on the driver's side.

The next obvious set of parts is the balast resistor(s). If you have a transistorized system, there will be TWO of them. If it's a conventional system, there will be only one. (Ever see highlander? in the series, there's a cool 280se 3.5 convertable. A lovely car) The balast resistors have different ratings. Take a look at the metal clip at the center of the balast resistor. The clip comes in blue, silver and gold. The blue and silver ones are for the transistorized system. The gold band is for the conventional.

Since you didn't mention the ignition module, lets assume you don't have one. That means the conventional system rules should apply. Up 'til this point, have you seen any of the wrong parts? (Anything blue?) Mismatching the parts is very common and leads to all sorts of foul things.

Now, for the wires that hold them all together. In the conventional system, the following wires exist:

- Wire from the ignition switch to the balast.
- Wire from the a/t to the other end of the balast.
- Wire from there to the coil, lead #15.
- Wire from coil lead #15 to the distributor (the GREEN wire). There will be a condensor here on the distributor.
- All the plug wires, including the one to the coil.

Now, for trouble shooting...

Test #1.

Remove the center wire from the distributor cap and ground it to something. Take off the distributor cap, rotor etc so that you can see and touch the points. Now, turn the key to the #1 position (no, don't start the car). BTW, when pulling plug wires, twist it a little first, then pull. It helps a lot.

- Voltage at 1st wire should be 12v (battery voltage).
- Voltage at 2nd should be less, but not less than 9v.
- Voltage at green wire will either be 9v or 0v.
If the points are open, you get the 9v value.
If the points are open, hand crank the motor to the
point where they are closed.

Using something that doesn't conduct electricity (your finger does), open the points and watch the meter read 9v.

If you can't convince the system to give you 9v, then the GREEN wire is shorted or broken. The screw it attaches to on the distributor is insulated from the distributor's body. It isn't that easy to screw this up, but I've done it. On that same screw post will be the condensor. It's a little barrel with one black wire lead. It is bolted to the distributor for a ground contact. If this item isn't there, you will surely destroy your points right quick.

Got 9v? Good, now you can put things back together again. As you do so, inspect your parts. Does the rotor look good and clean? If not replace it. Same goes for the cap. Are the wires old? Replace them all. A good set of bosch wires will set you back close to 100$. Pay it.

BTW, if you are reading DWELL when you run on the starter, then the green wire is fine. The only thing you have to worry about is the voltage being 9v. The dwell reading is nothing more than the percentage of time the voltage is 0v instead of 9v (how long the points dwell in the closed state).

Test #2

Hand crank the motor so that you have the 0 TDC on the #1 cylinder. Take a peek at the camshaft through the oil filler hole. Be sure that BOTH cam lobes for the #1 cylinder are pointing kind of up. If not, turn the crank one more revolution, since your on the exhaust stroke, not the power one.

Your rotor is now pointing to the #1 plug wire. With the distributor cap off, you should see a mark on the rim of the distributor that is hidden by the cap. That too is the indicator for #1. If they line up, that's good.

Does the plug wire at that position go to cylinder #1? Now, follow the rest of them. The next one on the distributor is the next on in the firing order.

Test #3

Put it all back together. Give it a shot of ether. Start the car. It should now be MUCH happer than it ever was before, especially if you've been charging the battery all this time. Take a well deserved snack break.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

CTH..
Thanks for the great reply!!

My distributor number is 0 231 116 052

My ignition coil is black, with an orange top on it. It has the large center wire that goes to the center of the distributor. The two small wires on either side have little rubber boots on them.
The + wire goes to and small cylinder (about the size of half a roll of nickels) which is connected to a piece of metal (like a mounting bracket? But, it's a ground, I think).
The - wire goes to the side of the distributor, to a little bolt. This little bolt is also home to another wire, which travels UNDER the distributor.

The MB dealership guys thought that ORIGINALLY, my car would have had the green wire which was actually a PART of the main center wire (if that makes sense). The green wire would have connected to the - side of the coil and then to the side of the distributor (I think!).

Now...I have no one to show me...so HOW do I turn the engine manually?? Do I need to take off the valve cover??
Should I take that cover off anyways??????

Am I crazy to be TRYING to do this????

~Christy

CTH da man!

Chuck (on vacation in Las Vegas)

But, that's a good kind of crazy. This comes from a guy that currently owns 6 of them.

OK, that + lead is going to your ballast resistor. What color is the metal clip that bolts it to the car?

The dealer guy was expecting your car to have the transistorized ignition. For those, that green wire is special. For a conventional system, it's just a piece of wire. Use any multi-strand, you can find, at 16 gauge.

Your distributor is from a 1968/69 model 250 for the US market. But you knew that already. Write these numbers down, you'll need them later...

The dwell at idle speed should be between 34 and 41 degrees. If you've installed new points, aim for 41. The maximum allowable difference between idle and 3,000 RPM is 3 degrees of dwell. More than that and you'll have to get the distributor rebuilt.

The timing is set to 37 at 4500 RPM w/o vacuum applied to the distributor. Be sure to plug the line with a cap.



OK. To hand crank the engine, you need a 28mm (that's 1 1/4 inch) socket an extension rod about 4 inches long and a breaker bar. Sears sells each of these. The 28mm socket will be a 1/2 inch drive one.

Dead center of the pulley on the crank, you'll find the bolt that the socket fits on. You might have a dust cover on the pulley, it prys off.

The engine is real easy to crank when some or all the plugs are removed. It can still be cranked when they're in place. It just takes more elbow grease.

-CTH

PS. For those that keep track of these things... a 27mm socket is needed for the M110, M116 & M117 engines. The M100 needs a 2 inch socket. The M189 has a funny bolt that you have to construct a tool for. I used a 32mm socket and a strip of steel welded into it like a giant screw driver blade.

__________________
- cth350@gmail.com
http://www.111lakeside.com/

CTH-

Ok...I went back out to try to see the color of the clip on this ballastor resistor (?).
It is so CRUDDY!! I keep on wiping it off, but it doesn't seem to BE a color. I think it's silver.

It ends up I gave some MISinformation...

...the + on the ignition coil has TWO wires coming off of it. Like I said, the little one goes to the Ballastor resistor....and there is a thicker one that goes to a weird, small-ish, rectangular thing. It appears to have a red (or maybe red/striped?) wire coming out of the bottom of the rectangular unit.

This may not even matter...

NOW...HOW MUCH elbow grease are we talking about, with this pulling the pulley thing? I'm NOT that strong!! Yikes!!

I WILL try, though... but NOT today..it's FREEZING here!!

Party on in Vegas, Chuck!!!!!!!!

~Christy

Actually, I'm on Long Island, NY. And I'm just Charlie (or Charles).

The breaker bar I use for turning the engine is 2 and a half foot long. That extra length sure helps.


A smallish rectangular unit, like the size of a book of matches? You sure that smallish thing isn't a connector with two sets of FOUR wires going into and out of it?

This is one of those times when a digital camera would sure come in handy.

OH, the small sucker, does it have TWO sets of wires comming off of it and it's black plastic? Perhaps just a little bit too big to fit in your hand? That would be a speed relay and it's picking up the engine RPM for emissions control logic.

Inside the door frame is a metal plate that says when your car was built and its chassis number. Please tell me the date code (i.e. 6/69) and the first 6 digits of the chassis number (i.e. 114.0xx). Based on that, I can give you more info.

-CTH

PS. And of course, it just dawned on me that the OTHER guy is also named Charles and HE'S in Las Vegas. Silly me.

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Hey Charlie (may I call you that?)

Ok here's the info....

114.011-12-019668

I am so excited that YOU know what these numbers MEAN!!!

And...the rectangular thing IS black plastic.

BTW...maybe you have some ideas on what could be MAJORLY wrong with this car. I mean, the guy probably wouldn't have sold it NOT RUNNING, if the problem were something MINOR!

~Christy

I found a 240D two years ago that was being sold for like 300$ because the transmission died. No more reverse. All it needed was a band adjustement done to fix it. Total time to repair was 30 minutes and zero dollars, which was mostly the time needed to crawl under the car and figure out the right size wrench. I didn't buy the car, I pointed it out to a friend along with the repair info. He's the one that made out.

Also, the PO may not have been as brave as you (or at least willing to get grease under his finger nails) and was paying somebody else by the hour to fix the car.

The car's chassis number is split into 4 fields.

114.011-12-019668 means that it's body style 114 and that it's a 114.011 car. That uniquely identifies it as a 250/8 according to http://home.hiwaay.net/~gbf/mbmodels.html

That also means, it should have a M130.923 motor in it.

Soooo, one or more of the following is wrong...

- The M130 motor that should be in your car has been replaced with an M114 motor (not the worse thing in the world).
- The distributor that should be on your M130 isn't right (not a good thing).
- The carbs AND distributor are wrong (doubtful, but bad).
- The web page is wrong and your car is just fine.

I'm answering this from my mom's AOL account, so I'll check my source info when I get home. In the mean time, get the engine number. It should be stamped into the side of the block about 6-10 inches over the oil filter housing on a flat spot. On older motors (a 114 might be so), it is stamped on a metal plate and the plate is rivited to the flat spot. If you can't get the motor number, get the raised numbers cast into the cylinder head. There should be a huge "250/A" or something like it. Also, there should be smaller numbers, like 114-xx-yyy-zzz or 130-xx-yy-zzz between the 3rd & 4th cylinders on the driver's side.

Also, lets have a sanity check on the carbs. The two jets on the carbs have small numbers stamped on them, something like x120 or x90. What numbers are present and are they the same for both carbs. The primary's number will be different from the secondary.

Getting back to explaining the chassis code, the -12- means it's a left hand drive automatic. The remaining numbers identify where it was in the production line.

-CTH

PS. Don't worry yet. WE (the collective list) will figure this out WITH you.

__________________
- cth350@gmail.com
http://www.111lakeside.com/

These engine numbers are really hard for me to make out!

Ok...here's what I got E-9 0
114 D ????????

Those letters/numbers are between plugs 3 & 4. Also between 5 & 6 it's has a HUGE 250.

So.....whoa!!!!! You think my engine has been switched out!!??? THIS engine STINKS ON ICE!!!!!!! What I mean is, it MUST have been switched a long time ago, because THIS engine has low compression and OOZES OIL all over the place...these REASONS are why I figured it was original (aka:OLD).

So.....I need another engine?!?!?!

OR...are you saying some (or alot) of my parts AREN'T compatable with this engine???


Oh...the carbs...the numbers on the jets are x120 & x100
AND.. this may be normal, but...INSIDE the carbs were ALOT of screws that had SOLEX stamped on them.....my carbs are the Zeniths...could THAT be normal??
~Christy



[Edited by bachlauter on 03-25-2001 at 07:28 PM]