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1973 mercedes 450sl
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3 Posts
Discussion Starter #1
the car is a 1973 450sl and won't start. I went through the fuel and everything is good there. I then tested the coil and see the coil doesnt have power and of course no spark? any ideas? It seems between the dist and coil there is no power. I am unsure where to turn at this point. Prior to the car not starting it was stalling out at stop signs and running rough. For the past two years when i do stop the car it almost stalled and the battery red light would come on inside the guage cluster.
 

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Benz 350 SLC 1971
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70 Posts
There is a kind of fuse (I dont know the acutal name in english) with long green wire comes from inside the distributor to the coil. Mine had same problem & I changed this fuse & problem solved.

If your engine is D Jetronic, there is a possibility that the amplifier of the coil is broken & not working. it is located under the front fender, left side.
 

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1973 mercedes 450sl
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3 Posts
Discussion Starter #3
thank you very much Khashi. I will look for a fuse for the green wire first and then check under the left front fender for a amplifier for the coil. I appreciate you taking the time to reply and help me.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,775 Posts
That is the condenser in the Distributor. (red dot), The other item mentioned is the switch gear. There are two ballast resistors on the left inner fender. Check to make sure they are getting power and that there is power out. Also with power off check for proper resistance.
 

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Benz 350 SLC 1971
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70 Posts
That is the condenser in the Distributor. (red dot), The other item mentioned is the switch gear. There are two ballast resistors on the left inner fender. Check to make sure they are getting power and that there is power out. Also with power off check for proper resistance.
thank you Rowdie. That is exactly what I was trying to say. :thumbsup:
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,775 Posts
I wasn't being condescending toward you Khashi. I hope you din't take it that way.
I know English is not your native language though you do better than some here.
 

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1973 mercedes 450sl
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3 Posts
Discussion Starter #8
thank you rowdie for your time. I am heading to look and check what you are suggesting- I will update later on today.
 

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Benz 350 SLC 1971
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70 Posts
I wasn't being condescending toward you Khashi. I hope you din't take it that way.
I know English is not your native language though you do better than some here.
Of course I did not. I am happy that I am learning & still have much long way to learn more in here from you & many other nice & expert gent's. :thumbsup:
 

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Premium Member
1975 450SL
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2,440 Posts
When I had a very similar problem, the answer turned out to be the breaker points. They had a coating of dirt and oil on them that was non-conductive. A few moments of rubbing with some stiff paper cleaned it off.

You may also want to check the gap of the points. The manual says to use a dwell meter to set them to a dwell of 30 to 35 degrees.

Hope this helps.
Scott
 

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Premium Member
1975 450SL
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2,440 Posts
If you are having trouble with your switchgear, you might want to go to a breakerless points conversion from Pertronix or S&S. I had to do that because I was having points problems very often. I suspect I have shaft wobble in my distributor.

How I found one points problem was by metering them and seeing an open when they were closed.

Scott
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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10,015 Posts
If you are having trouble with your switchgear, you might want to go to a breakerless points conversion from Pertronix or S&S. I had to do that because I was having points problems very often. I suspect I have shaft wobble in my distributor.

How I found one points problem was by metering them and seeing an open when they were closed.

Scott
Hi Scott - Did you use a Pertronix? I have on my '72, but I thought I read somewhere that it wouldn't fit in the '75s distributor.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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10,015 Posts
radio - did you just replace the points with the 1885 or did you install an entire ignition system?

Thanks!
Don't know about Radio, but I installed the 1885, but left the switchgear in place. This just replaces the points. It helps if you think the distributor shaft may be wobbling.

But if you suspect the switchgear is bad, then you need to wire so Pertronix takes the place of the switchgear. You should also change the coil.

I have heard that there may a problem getting tach to work with full Pertronix conversion on the very early 107s. But don't have firm data on this.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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10,015 Posts
When I had a very similar problem, the answer turned out to be the breaker points. They had a coating of dirt and oil on them that was non-conductive. A few moments of rubbing with some stiff paper cleaned it off.

You may also want to check the gap of the points. The manual says to use a dwell meter to set them to a dwell of 30 to 35 degrees.

Hope this helps.
Scott
My first thought, was to check the gap in the points. Just set them to about 0.014" (If you don't have a feeler gauge, that is about the thickness of a business card). If you don't know how, we can help. The dwell meter is a btter way, but you have to set the gap approx right first anyway - At 0.014", I found the dwell was about right.

Then check and clean all the electrical connections and make sure that green wire isn't shorting to ground anywhere. I once had mine melt plastic cover and short to exhaust manifold! Similar symptoms.
 

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Registered
1973 450SL -- 1988 560SL
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25 Posts
ok - the - "switch-gear" is the tranistorized unit in the wheel well that actually controls the coil / distibutor for spark. In my case it has a total of (4) wires going to / from it.
 

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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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22,019 Posts
Should I add the switch gear to the list of parts to pickup from parts cars in the JY, or is the consensus that there are enough floating around here because everyone likes to switch to Pertronix?

Or is there another reason to assume it's not worth picking them up from the JY, which is that if the car is in the JY the switch gear is likely to be no good?

Should I add it to my list?
 
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