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samuelsantana Samba Member
Joined: February 11, 2010 Posts: 4 Location: orlando,fl
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Posted: Thu Aug 25, 2011 6:29 pm Post subject: Engine and coil problems |
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Hey guys, I am having a bit of a problem with my recently rebuilt 1641cc motor. when I leave the car the car on idle for like 20 minutes (hatch open) the coil will heat up more than normal and then the motor will start to heat up also. I have replaced the coil 3 times with new and original ones and they do the same thing. What I am wondering is if these 2 problems are connected. The motor was also placed in the correct timing position with a timing light. Any help is appreciated thank you. |
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Bikerchris Samba Member
Joined: May 08, 2010 Posts: 290 Location: Texas
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Posted: Thu Aug 25, 2011 7:20 pm Post subject: |
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I had a problem similar to this once and it seems to me it turned out to be the wiring in the ignition switch. Does that sound logical to you? |
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RailBoy Samba Member
Joined: March 10, 2008 Posts: 2904 Location: Virginia
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Posted: Thu Aug 25, 2011 7:27 pm Post subject: |
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Resistor....????? RB |
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lostinbaja Samba Member
Joined: December 19, 2004 Posts: 4036 Location: Frankfort, Illinois
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Posted: Thu Aug 25, 2011 7:31 pm Post subject: |
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Some coils have an internal resistor and some require external resistors. A coil spec'd for a 12v VW will have an internal resistor. I take it you have a 12v system? _________________ Jerry...
If it's being towed, it must be a trailer!
"Vee Grow Too Soon Oldt Und Too Late Schmardt"
RIP Morgan
My photos
http://www.manxgallery.org/gallery/album92 |
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RailBoy Samba Member
Joined: March 10, 2008 Posts: 2904 Location: Virginia
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Posted: Thu Aug 25, 2011 8:18 pm Post subject: |
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Not so sure about that, have seen motors with 12 Volt & Resistors mounted to the fan shrouds, they looked stock..... But it was a while ago, could have been 6 volt systems though..... RB |
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samuelsantana Samba Member
Joined: February 11, 2010 Posts: 4 Location: orlando,fl
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Posted: Fri Aug 26, 2011 3:17 am Post subject: |
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Yes its a 12v system and as far as I know the coil has a built in resistor. We thought it was a resistor problem but all 3 of my coils got hot. I don't think I have 3 bad coils. This motor is in a 1966 bus and before I purchased it, it was converted to 12v from 6 volt. Also when I rebuilt the motor I changed the generator to an alternator. Thanks guys |
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modok Samba Member
Joined: October 30, 2009 Posts: 26787 Location: Colorado Springs
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Posted: Fri Aug 26, 2011 3:34 am Post subject: |
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The coil should have a resistance of 3-4 ohms for points or the usual modules. Across the 12V and points lugs.
The resistance is the main thing that determines how much power they draw. |
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RockCrusher Samba Member
Joined: August 03, 2010 Posts: 4596 Location: Parkesburg, PA
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Posted: Fri Aug 26, 2011 3:52 am Post subject: |
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modok wrote: |
The coil should have a resistance of 3-4 ohms for points or the usual modules. Across the 12V and points lugs.
The resistance is the main thing that determines how much power they draw. |
You're up mighty early today! E=IR or I(4amps)=E(12volts)/R(3ohms).
Don't let the 4 amps scare you coz it's intermittent current and peak at that. The inrush current is 4 amps and decreases as the magnetic field builds and the total time is 50* x 2 per engine revolution of 360* so the heat rise should be less than the equivalent of 1 amp at 3 ohms full time....more like .25 amp heat. Of course the faster the engine turns the higher the average current.
RC
EDIT-I said that backwards (I see, now that I'm awake) The resistance is high at the beginning and lessens as the with time so the current gets higher with time on each cycle BUT as cycle frequency increases with RPM the inductance shows increasing impedance so the current becomes less and less with increasing RPM. That's why the output voltage starts to drop off over the coils RPM limit in typical ignition systems. _________________ [email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly.
Last edited by RockCrusher on Fri Aug 26, 2011 8:28 am; edited 2 times in total |
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modok Samba Member
Joined: October 30, 2009 Posts: 26787 Location: Colorado Springs
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Posted: Fri Aug 26, 2011 4:07 am Post subject: |
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Oh crap, I forgot to sleep |
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samuelsantana Samba Member
Joined: February 11, 2010 Posts: 4 Location: orlando,fl
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Posted: Fri Aug 26, 2011 4:46 am Post subject: |
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please help, I'm loosing sleep over these. |
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modok Samba Member
Joined: October 30, 2009 Posts: 26787 Location: Colorado Springs
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Posted: Fri Aug 26, 2011 4:38 pm Post subject: |
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man, this morning was rough
Anyway, if the points have somewhere near the right gap and dwell, and the coil has the correct resistance, and it's hooked up right, and you tried three coils, then it must be ok.
right? |
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