Author Topic: No spark-coil problem?  (Read 10310 times)

seattle_Jerry

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No spark-coil problem?
« on: May 28, 2008, 21:52:25 »
Nothing like a subject thats been beat to death...and yet is still confusing.

I did the plug wire next to the block spark test- nothing
Coil wire next to the block - nothing

Voltage to coil - around 6 to 7 V
Resistance across +/- with coil disconnected from car - 12.5
Resistance between coil output socket and + terminal - 1.6

Its a 67 230SL with what appears to be the original coil. It is terracotta red on top.

My coil to dist. wire is 7.28
plug wires - 1.22 except for that stupid 5.22 on #1

So from what I gathered...it doesn't hurt to replace the coil with the red sticker and cooresponding resistor.

I looked around the site and tech manual and didn't see any values for what the coil should measure at for resistance. The voltage going in seems in range from what I read.

I guess I just want to make sure I order everything I need.

Benz Dr.

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Re: No spark-coil problem?
« Reply #1 on: May 31, 2008, 10:35:55 »
Are you saying the coil wire is over 7,000 ohms? You should have close to zero for best performance.
The later sets with screw on resistors are 1K each so that should be about 2.1 - 2.5 at the most.

Open and close the points with a screw driver ( points should be closed ). If you get a spark the points are bad and if the spark comes from the tip of the of the screw driver that's normal. If it comes from the shaft of the screw driver where it's rubbing against the points the condesnor is bad.
Coils rarely fail.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

seattle_Jerry

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Re: No spark-coil problem?
« Reply #2 on: May 31, 2008, 11:53:35 »
Thanks! I'll try that out.

seattle_Jerry

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Re: No spark-coil problem?
« Reply #3 on: June 01, 2008, 02:22:39 »
yeah I just double checked the resistance on the coil wire. 7000 ohms. What really sucks is they are brand new, but have sat in the garage for 6 months , so its not like I can return them.

Benz Dr.

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Re: No spark-coil problem?
« Reply #4 on: June 01, 2008, 11:30:31 »
Is the coil wire one with resistor ends? You might be able to remove them and put regular ends on instead. If you have steel core it should go down to zero resistance.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

seattle_Jerry

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Re: No spark-coil problem?
« Reply #5 on: June 07, 2008, 02:25:55 »
I did the test and got no spark from anything (points, screwdriver etc.) I also got no spark with the coil wire held just off the block.
New coil?
Sorry I haven't had the chance to call you back Dan.I get busy with work in the morning and then it is past 5 PM in your time zone.


Benz Dr.

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Re: No spark-coil problem?
« Reply #6 on: June 07, 2008, 17:47:20 »
Check to see if you have voltage at the coil coming from the main wiring harness. In this case, you would be looking at the wire going to the ballast resistor first. If you have voltage there but nothing going to the coil the ballast resistor is probably fried.
If voltage is going through the resistor then it looks a lot more like the coil is bad. Good time to put the red coil and ballast resistor in there.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

seattle_Jerry

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Re: No spark-coil problem?
« Reply #7 on: June 07, 2008, 18:04:41 »
Yup I have voltage at the coil. So I guess add that to the order.
What is sad is that I took the PO's word that it was a bad ignition switch that was the reason for the car not running. So I have a new one of those too.

Who knows...maybe it was bad too or the coil was already on its way out. I guess what do I expect from a $10,000 car ;)

ja17

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Re: No spark-coil problem?
« Reply #8 on: June 08, 2008, 21:24:47 »
Hello Jerry,

Make sure the points are opening.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

seattle_Jerry

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Re: No spark-coil problem?
« Reply #9 on: September 01, 2008, 02:22:02 »
Finally got a chance to put in the parts I got ages ago. New red coil and resistor, condensor, points and correct wires.

Still no spark. :( I don't see anything when I pry the point apart with a screwdriver either.

I'm reading 4 volts at the coil.

On the resistor, where does the wire that connects next to the black dot connect on the coil? left (+) or right (-) as you look over the fender?

I am starting to suspect that something was wired wrong by the PO while troubleshooting his non-running car.

The wire on my resistor comes off the black dot terminal to the + on the coil.

On the "-" side there is a red wire of mystery coming out of the harness and a blackwire that goes to bolt on the side of the distributor. This is also where the condensor wire attaches.

hands_aus

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Re: No spark-coil problem?
« Reply #10 on: September 01, 2008, 07:37:37 »
Is the little isolating rubber grommet on the small bolt on the distributor that the condenser conencts to still there?
Maybe there is a short to earth.
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

glennard

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Re: No spark-coil problem?
« Reply #11 on: September 01, 2008, 07:56:58 »
Jumper 12v from the battery directly to the 12v(high) side of the coil(disconnect the existing wires-green/black?).   It's a short trip.  Bypasses everything.  Should then have(with the points open) 12volts at both other coil spots and 12v at the points contact-hot side.  Otherwise, you've a short to ground-and smoke!  There should be no other wires in that part of the circuit.  Car/engine should/will run with the jumper. Gotta disconnect to stop it.
« Last Edit: September 01, 2008, 07:58:18 by glennard »

seattle_Jerry

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Re: No spark-coil problem?
« Reply #12 on: September 01, 2008, 21:35:24 »
I was checking the bolt on the dist. per Bob's suggestion. That ended up not being the problem, although it looked like it..but it got me checking continuity.

It turns out that there is continuity from ground/earth to the power coming into the resistor. So I have to track that down.

glennard

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Re: No spark-coil problem?
« Reply #13 on: September 02, 2008, 07:53:05 »
That's the same point(high side of the resistor) as the high side of fuse 2, the 'Run' contact on the ignition s/w, and alternator light. (The Start/Run/Coil/Dist circuitry is unfused.) You've a short somewhere.  Did it run on the jumper to the coil?

graphic66

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Re: No spark-coil problem?
« Reply #14 on: September 02, 2008, 12:08:29 »
Could be the condenser, very easy to check, just put another one in. I shorted mine for just a second adjusting the points and it fried instantly.

seattle_Jerry

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Re: No spark-coil problem?
« Reply #15 on: September 02, 2008, 23:00:49 »
I haven't tried jumping yet per your instructions. I'm still trying to find out why that wire is grounded.

seattle_Jerry

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Re: No spark-coil problem?
« Reply #16 on: September 04, 2008, 19:23:24 »
I've traced the problem back to a short in the wire that goes to the ignition light. Its kinda funny that a light can keep your car from starting.

The short is somewhere between the wiring harness junction next to the hood release and the center gauge in the dashboard.

hands_aus

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Re: No spark-coil problem?
« Reply #17 on: September 08, 2008, 19:45:05 »
quote:
Originally posted by seattle_Jerry

I've traced the problem back to a short in the wire that goes to the ignition light. Its kinda funny that a light can keep your car from starting.

The short is somewhere between the wiring harness junction next to the hood release and the center gauge in the dashboard.


I think the iignition light wire is in parallel with a wire to fuse #2, that connects to the ignition switch.
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best