Author Topic: Ignition Coil - Testing (Read 17975 times)

bpossel · « **on:** April 04, 2005, 07:05:58 »

Question....

I have the bosch "blue" ignition coil. Looks old and original...
What should the correct ohms measurement be to ensure the coil is still good?

With all lines disconnected... mine currently measures 0.7 between the small terminals (+-), and 9.19 between the center and either of the small terminals (+-)

Is mine still good?
Thanks!
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

Benz Dr. · « **Reply #1 on:** April 04, 2005, 08:27:13 »

I've been providing people with the red top coil and balast resistor for quite a while now and this hotter coil should be your answer.

black coil is 13 VK
blue coil is about 18-20 VK
red coil is 26 KV ( 26,000 volts )

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org

bpossel · « **Reply #2 on:** April 04, 2005, 09:02:40 »

Hi Dan,

Does my coil need to be replaced, based on the ohm readings that I am getting?
Thanks,
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

ted280sl · « **Reply #3 on:** April 04, 2005, 10:12:19 »

Bob,
Even if your old coil is functional you should consider the Doctor's advice. This is among the cheapest upgrades you can do. Your car will start faster and run better with the hotter coil. Changing the coil and ballast are very easy.
Ted 1969 280SL w/ red coil and ballast

J. Huber · « **Reply #4 on:** April 04, 2005, 12:37:55 »

I agree with Ted and Dr B. Having the red coil (and the right spark plugs) makes a big difference. Don't ignore spark plug wires either, as again having new and good ones helps things. Combined with a ship-shape cold start system and you'll be pleased every time!

James
63 230SL

n/a · « **Reply #5 on:** April 04, 2005, 12:59:33 »

I understand that the late 69 through 71 280sl cars are installed with transistorized ignition and need to use the blue coil. One needs to bypass the transistor box (silver box) in order to use the red coil. Would like to get confirmation from other members. Would also like to know how difficult it is to do the bypass? (Is it like the heart bypass?[:p])

Louis 70 280sl red

bpossel · « **Reply #6 on:** April 04, 2005, 13:29:34 »

What is the Bosch part number for the Blue, vs Red...
I have found that the Bosch coil that replaces the Blue one is 0221 122 001.

What is the PN for the red one?
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

J. Huber · « **Reply #7 on:** April 04, 2005, 14:36:52 »

Hey Bob

All the usual 113 guys appear to have the red coil. Their part numbers vary -- but price is about same -- about 45 bucks.

One reference I saw was Bosch number 0 221 119 030, but I would confirm this. I will check mine when I get home.

James
63 230SL

J. Huber · « **Reply #8 on:** April 04, 2005, 17:32:13 »

As promised, mine appears to read 0 221 119 030 (KW 12V).

James
63 230SL

bpossel · « **Reply #9 on:** April 04, 2005, 17:41:37 »

Hi James,

Thanks for looking at your coil and part number!
Is your coil all red, or silver with a red label?
Bob

quote:
Originally posted by J. Huber

As promised, mine appears to read 0 221 119 030 (KW 12V).

James
63 230SL

bpossel
Memphis, TN.
1971 280SL
1997 E320

J. Huber · « **Reply #10 on:** April 04, 2005, 17:51:37 »

Very good question. It is silver with a red label.

James
63 230SL

bpossel · « **Reply #11 on:** April 04, 2005, 19:17:59 »

Thanks James!

If I have the transistorized ign., do I still need to upgrade to the 1.8 ohm ballest?

I think the 1.8 ballast is for non-transistorized?

Bob

quote:
Originally posted by J. Huber

Very good question. It is silver with a red label.

James
63 230SL

bpossel
Memphis, TN.
1971 280SL
1997 E320

Naj ✝︎ · « **Reply #12 on:** April 05, 2005, 02:37:37 »

Bob,
Does your blue coil set-up not have 2 ballast resistors at the moment?
naj

65 230SL
68 280SL

bpossel · « **Reply #13 on:** April 05, 2005, 05:53:10 »

Hi Naj,

Yes, I have 2 ballast resistors (0.4 & 0.6 ohm). I have a very old Bosch Blue Coil. No stickers, labels... these are gone. On the bottom of the coil are the following numbers stamped into the coil housing:
0221 118 005
023
W12V

Regards, Bob

quote:
Originally posted by naj

Bob,
Does your blue coil set-up not have 2 ballast resistors at the moment?
naj

65 230SL
68 280SL

bpossel
Memphis, TN.
1971 280SL
1997 E320

Naj ✝︎ · « **Reply #14 on:** April 05, 2005, 07:01:26 »

Yaa Bob,
I was going to say fitting a red coil with only one resistor may affect transistorised ignition box with change in current going thru it.
Need expert help here!
naj

65 230SL
68 280SL

J. Huber · « **Reply #15 on:** April 05, 2005, 08:51:39 »

quote:
...Need expert help here!
naj

That clearly bumps me out! Dr. Dan?

James
63 230SL

George Davis · « **Reply #16 on:** April 05, 2005, 10:09:05 »

Well, this may go against the common wisdom, but I'll put it out here anyway:

First, old coils are... well, old, and old coils eventually fail. In the interest of reliability, I think they are worth replacing.

So, I replaced my old standard (blue?) coil, and decided since I was replacing anyway, I'd go for the red coil. No regrets, but I also noticed no difference between the blue and the red, so I'm not sure it is really all that necessary. In the case of the later US cars with the transistorized ignitions, my inclination would be to stay with the standard set-up.

George Davis
'69 280 SL Euro manual

bpossel · « **Reply #17 on:** April 05, 2005, 10:56:08 »

Hi George,

Thanks for your comments on what you did....

Question? When you installed the red coil, did you also replace the .6 ohm ballast with the 1.8 ohm ballast?

Thanks,
Bob

quote:
Originally posted by George Davis

Well, this may go against the common wisdom, but I'll put it out here anyway:

First, old coils are... well, old, and old coils eventually fail. In the interest of reliability, I think they are worth replacing.

So, I replaced my old standard (blue?) coil, and decided since I was replacing anyway, I'd go for the red coil. No regrets, but I also noticed no difference between the blue and the red, so I'm not sure it is really all that necessary. In the case of the later US cars with the transistorized ignitions, my inclination would be to stay with the standard set-up.

George Davis
'69 280 SL Euro manual

bpossel
Memphis, TN.
1971 280SL
1997 E320

n/a · « **Reply #18 on:** April 05, 2005, 11:30:03 »

Bob,

How can you tell that you have a transistorised ignition box and two ballasts?

I have a 70 280sl; the ignition coil is old and I cannot tell if it is blue, red, or silver. It has two little terminals on top; one has a #1 and the other has a #15 next to it. I think the #1 terminal is grounded and the #15 terminal is connected to a long connector(or box?) mounted on the engine bay wall next to the coil. I am considering replacing it with the red coil but not sure if it is the right coil to use. How complicated is the procedure to replace the coil and the balast?

Thanks,
Louis

George Davis · « **Reply #19 on:** April 05, 2005, 11:43:25 »

Bob,

yes, I replaced the ballast with the 1.8 ohm. One would 'think' that the the 1.8 ohm ballast plus red coil would be correct for the transistor set-up, but I'm not so sure. The primary side of the coil doesn't really see a simple 12 volts, switched on and off periodically. The primary side sees voltages from 0 to several hundred (gives quite a shock, too, ask me how I know), in a sinusoidal waveform which is related largely to the inductance of the coil. The secondary side does something similar, although on that side it's several thousand volts. So the question is, does the transistor system simply mimic, as exactly as possible, the old breaker points, or is the entire system "tuned" to the inductance characteristic of the coil? If it's the first, then throw on a red coil with 1.8 ballast and go. If it's the second, then stay with the standard set-up. Trouble is, I haven't seen an answer posted here or anywhere, and this is pretty much the limit of my knowledge of electrical engineering, so I'm inclined to play it safe and stick with the standard set-up.

George Davis
'69 280 SL Euro manual

bpossel · « **Reply #20 on:** April 05, 2005, 11:45:01 »

Louis,

One reason I know is that my car is a later '71 model year (prod 6/70). Under the battery box is where my ignition transistorized modual resides. Here is a picture of the modual. I had it out for cleaning when I replaced my radiator a couple of months ago. On the unit is marked with the following: HB12V 0227051 015 229
I have 2 ballast resistors (0.4 and 0.6 ohm) that are attached to the car frame on either side of my ignition coil. Their ohm rating is marked on the metal band which surrounds the actual ballast itself. The 0.6 ohm ballast is connected on one end to the positive side of the coil, the other end connects to the transistor modual. The 0.4 ohm connects to the transistor modual and then also to the distributor.

I am also attaching a diagram of the ignition system. Dont recall where I got this from, Joe? Dan? Anyway, it helps to see the setup.

quote:
Originally posted by ll2002

Bob,

How can you tell that you have a transistorised ignition box and two ballasts?

I have a 70 280sl; the ignition coil is old and I cannot tell if it is blue, red, or silver. It has two little terminals on top; one has a #1 and the other has a #15 next to it. I think the #1 terminal is grounded and the #15 terminal is connected to a long connector(or box?) mounted on the engine bay wall next to the coil. I am considering replacing it with the red coil but not sure if it is the right coil to use. How complicated is the procedure to replace the coil and the balast?

Thanks,
Louis

Download Attachment:

transistor module.jpg
40.8 KB

bpossel
Memphis, TN.
1971 280SL
1997 E320

Download Attachment:

transistorized ignition.jpg
63.39 KB

n/a · « **Reply #21 on:** April 05, 2005, 12:26:49 »

Bob,

Thank you for the diagram. The diagram matches the 1 and 15 on top of my coil. Now I need to see if I can find the transistorized modual. Do you need to remove the battery to see it? So far I have only seen 1 ballast resistor that is attached to the car frame forward of the coil. I will try to verify it's ohm rating.

Louis

bpossel · « **Reply #22 on:** April 05, 2005, 16:37:32 »

One other item that really puzzles me is that on the negative side of my coil, it is not grounded. The small brown ground wire is next to the coil, connected to the chasis, but not to the negative side of the coil.

This evening, I tried to reconnect this ground to the negative side of my coil and start my car. The starter rolled over, but engine never started. I disconnected this small ground wire and with one turn of the key, the engine fired right up.

Why is this? Anyone of our fellow 113'ers know what may be causing this ground to not permit me to start the car? According to the wiring diagram, the negative side of the coil should be grounded.

Comments, advice?

Thanks,
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

George Davis · « **Reply #23 on:** April 05, 2005, 17:43:35 »

Bob,

the wiring doesn't sound right. Earlier you posted that the 0.4 ohm resistor connects to the transistor module AND THEN ALSO to the distributor. The wiring diagram doesn't show this second connection to the distributor. The third terminal (7) of the transistor module should be connected to the distributor.

What is the negative side of the coil (I assume this is terminal 1) connected to?

George Davis
'69 280 SL Euro manual

bpossel · « **Reply #24 on:** April 05, 2005, 18:31:35 »

George,

You are absolutly right! I need to retrace the negative side of the coil. There is a black wire connected to the negative side of the coil that runs towards the distributor. I will look tomorrow evening and repost findings.
Bob

quote:
Originally posted by George Davis

Bob,

the wiring doesn't sound right. Earlier you posted that the 0.4 ohm resistor connects to the transistor module AND THEN ALSO to the distributor. The wiring diagram doesn't show this second connection to the distributor. The third terminal (7) of the transistor module should be connected to the distributor.

What is the negative side of the coil (I assume this is terminal 1) connected to?

George Davis
'69 280 SL Euro manual

bpossel
Memphis, TN.
1971 280SL
1997 E320

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Author Topic: Ignition Coil - Testing (Read 17975 times)

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