Car wounldn't turn over. The old points were pitted and one side was gone completely.Put in new tune up parts: cap, rotor,points and condenser. Tried to start it and sparks flew and battery smoked. Dwell meter reads well when ignition coil checked. Is the coil still ok? Switched batteries and it happened again then stopped. Turned out to be a really loose connection (oops). Checked everything, seems fine, but still won't start!!! Any ideas?

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"Marilyn"
1968 280 SE

Does this only happen when you are turning the engine over on the starter?

Is it OK with the ignition switch on?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

the battery spark stopped. apparently there was just a really loose connection. however the car still won't start. it's It turns over but seems to more hiccup than actually start.

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"Marilyn"
1968 280 SE

Can you check for spark? A good way is to put a timing light on any plug wire and see if it flashes while cranking.

Is the fuel pump running? Do you have pressure at the fuel filter in the engine compartment?

Is the cold start valve working? Can you hear it click?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

if you have spark and compression and fuel you should start, providing the ig timing and valve timing are on.

if compression or valve timing are off you will not any compression pulses when cranking. it will turn too smoothly.

if it feels as if you are getting comprssion and you have spark a little gas squirted or ether into the intake should bring firing.

if the ig timing is off too much you will get backfiring if you have compression spark and fuel.

if you have no spark you might have the point gap too close or too wide.

good luck

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

We can hear the cold start valve click, though we couldn't find it to adjust it and the book doesn't tell us where it is!! The fuel pump is running. We even removed a hose up in the engine to bleed out the air and had fuel spit out at us very quickly. Believe the fuel pressure is fine. We checked for spark and have it, though it is orange rather than blue. Believe this may be due to a dying battery? All the ignition parts are brand new. Tried to start it again this morning and still get the hiccup. We are waiting for the rain to pass to try re-adjusting the points.

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"Marilyn"
1968 280 SE

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The CSV [ cold start valve] is on the intake manifold...rightside . in the middle... one wire going to it and a steel gas line feeding it from the fuel filter.
It is not adjustable.

Here is how it works.
When the starter is cranking a cold engine, a 12v sig feeds the CSV solinoid and that energizes the valve , which squirts a little petro into the intake..this is a start assist primer. Very simple device.

Here is a simple test.
Have someone crank the starter when engine is cold and see [ with a test lamp/ or feel it for a click]... if there is 12v at the wire terminal on the CSV...if NO, then you have an electrical feed problem... [ Hearing a click can also be the relay or another enrichment device on the pump ,so test lamp is best verification]
If yes , then you will notice that there is a little 7mm cap screw on the side of the CSV..this is a CSV TEST PORT... [ wasn't that nice of them ]
If you take this cap plug off , you can then place a rag over the opening and have someone crank again [ disconnect the coil so the engine does not start]. Gas will leak out the test port hole when the starter is engaged. This verifies the valve to be getting fuel and working ..if NO, then take the line off and see if you have fuel feed there when key is ON [ from the electric pump]
There is a screen in the CSV , so if you have fuel to the CSV , but none at test port and you can hear the CSV click, then the screen may be plugged..
This is only a starting aid and will not cure an ignition problem, but I mention it B/C without a CSV operating , these engine do not like to start ..so, this simple test will put that part to rest before getting into ignition diagnosis....

Thanks for all your advice!! Here's what we have so far:
OK-Don't have a test lamp, but click is there. Took plug cap off and there is fuel. Used a dwell meter on the ignition coil and it registers at 40 degrees. When checking spark from coil to body there is steady spark, but it is orange, not blue.....ideas?

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"Marilyn"
1968 280 SE

Do you have an ohm/volt meter?

Yes.

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"Marilyn"
1968 280 SE

There were 3 versions ignition

See if you have two ballast resistors and ohm them [ out of the circuit]..also report if the neg side of the coil goes to chassis ground.

Thanks for getting back so quickly!

The neg side of the coil goes into an adjacent line of wiring and we don't know where it goes from there. Don't quite understand what you mean by ballast resistors...(sorry!!)

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"Marilyn"
1968 280 SE

The + wire to coil comes from a resistor..Little white ceramic , 2 wire resistor..can you see this??

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=21H0MN3YU21W196Z7Q&year=1968&make=MB&model=280-SE-001&category=F&part=Ballast+Resistor&appChassis=_any

Yes...can see that. Check with ohm? What reading are we looking for?

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"Marilyn"
1968 280 SE

Depends on which ignition system you have .. there were 3 versions for that model, as they were in a transistion period for transistor ignition systems at that time.
The VIN will tell me that or the ohms will ..you have to disconnect one side to get correct ohms reading [ so you do not get system backfeed reading]
I can not tell you which diagnostics procedure to use until I know which system version you have.. if you look at the link I posted , you will see the different ohms reading and you will see which serial # your car calls for..

If you do not have the VIN, does your car have one of these near or under the battery?
http://catalog.worldpac.com/mercedesshop/sophio/image.jsp?title=Ignition%20Control%20Unit&url=http%3A//img.eautopartscatalog.com/live/F600049626PRO.JPG