 Ignition Coil, Test Procedure |
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| CG-914 |
 Jul 30 2013, 10:51 PM
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#1
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Member  Group: Members Posts: 326 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California  |
I have a 74 2.0 with the blue bosch coil
I wanna test my coil. What are the ohm numbers I need to see between which points? Wich wire is ground? Is the other getting 12V? Side question: Whats the threat on the oil drain plug? |
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| McMark |
Jul 31 2013, 12:16 PM
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#2
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914 Freak! Group: Retired Admin Posts: 20,180 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
The only real test is to bolt on a new one and see if the problem goes away. You should have close to zero ohms between the LT connections (1, 15 or +,-). Most coil problems arise when they are hot and aren't a dead short. So testing with an ohm meter isn't helpful.
The only true test is to use a scope on the engine while it's running and analyze the feedback, which takes expensive equipment and extensive knowledge. |
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| TheCabinetmaker |
Jul 31 2013, 12:55 PM
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#3
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I drive my car everyday Group: Members Posts: 8,373 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
No threat on the drain plug. New cruch washer and proper torque. However, The strainer cover is a different story. Its only torques to 8 ft lbs. The pick up for the oil is held in place by one of the engine case bolts. Too much torque on the strainer nut can pull the bolt and crack the case rendering it useless.
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| nathansnathan |
Jul 31 2013, 04:49 PM
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#4
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Senior Member Group: Members Posts: 1,052 Joined: 31-May 10 From: Laguna Beach, CA Member No.: 11,782 Region Association: None |
Ratwell gives some info on blue coils on his bus pages
QUOTE Bosch Black coil (factory original Germany) 0 221 119 020 or 00015 (VW 022 905 115C) turns: 100-1 (unverified) primary: 3.0 Ohm secondary: 9.83 kOhm Bosch Blue coil (Brazil) 0 221 119 027 or 00012 (VW 043 905 115C) turns: 150-1 (unverified) primary: 3.4 Ohm secondary: 7.79 kOhm http://www.ratwell.com/technical/BlueCoil.html The numbers in this image aren't relevant, I think because of the resistor in the blue coil, but it shows how to test primary vs secondary. (IMG:http://www.914world.com/bbs2/uploads_offsite/www.international-auto.com-11782-1375310967.1.gif) |
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| CG-914 |
Aug 1 2013, 11:48 PM
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#5
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Member Group: Members Posts: 326 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
Thank you for the help.
I was asking about the threat size from the oil drain, to get the right size crush washer... |
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| Elliot Cannon |
Aug 1 2013, 11:59 PM
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#6
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914 Guru Group: Retired Members Posts: 8,487 Joined: 29-December 06 From: Paso Robles Ca. (Central coast) Member No.: 7,407 Region Association: None 
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QUOTE(CG-914 @ Aug 1 2013, 10:48 PM)  Thank you for the help. I was asking about the threat size from the oil drain, to get the right size crush washer... Thread size. Plug size. (IMG:style_emoticons/default/biggrin.gif) |
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| bulitt |
Aug 2 2013, 05:23 AM
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#7
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Achtzylinder Group: Members Posts: 4,189 Joined: 2-October 11 Member No.: 13,632 Region Association: South East States |
Pull the wire going from the coil to the distributor and hold it with gloves 3/8" from ground, watch as someone cranks the engine, if you get bright blue spark its working fine. However that little blue bosch coil is never going to through the juice of a MSD blaster. IMO
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