Unknown electrical part

[TomJ]

Hi:

Well the jeep quit running the other day and we're trying to figure out why. �On the wire running from the battery to the coil is this little unit, don't know if its the problem but it's gettting really hot. �So hot it burns you if you touch it. �Anybody know what this is? �The guys at the auto parts store don't and the people at Radio Shack don't and we certainly don't! �I don't know if this is the problem but wondered about it anyway.
The jeep was sitting at idle and just stopped running.

Tom

[athawk11]

Tom,

It looks like a resistor to me.  Has your Willys been converted to 12v?  Don't quote me, but if your coil is 6v, this could be reducing the voltage from a 12v battery to the 6v coil.    

A resistor will get very hot.  Especially one that size.  A light bulb is a resistor of sorts.  Think about how much heat they put off.  

Again, above is just a guess Tom.  Give us some more symptoms.  Does the battery still turn the starter?  Do other electrical items still turn on when you turn the ignition?  Is the fuel pump delivering fuel to the carb?  

Tim

[Macgraham]

If you have a 12 volt system you can get a new coil with a built in resistor for about $20. Cleans things up a little. Mac

[p3ferris]

Looks like a resistor to me also.  Radio shack, they are just sales people.

[bretto]

Where you found it, I suspect a resistor also.   It's probably the improper wattage, hence why it's gets real hot.  Looks sketchy also.  You should have something that is around rated around 200 watts.  Google ballast resistor.
Leave RadioShack people to sell cell phones.

[Quebec Jeep]

I'm not sure if this is a resistor. For me, as far as I can see it's look like a diode.

A diode is used to prevent a current to return. Maybe used to prevent the battery to get discharged.

I may be wrong here but it's my guess

[johnrb3b]

Yes, the picture is of a common silicon diode - probably a 1N400x series.
There's no reason for a diode in the line to the coil.
And if it's a diode, it really shouldn't get hot either.
Seems odd.
As others have said, it's common to use a dropping resister to run a 6V coil on a 12V conversion. It should be rated high enough wattage to get barely warm to the touch.

[TomJ]

I did a little more looking around (it's been a while and I couldn't remember) we did do a 12 volt conversion but the coil we have on there is marked 12v.  Fuel pumps working, I can smell gas in the carb, it appears we're getting spark, and we tried hot wiring past the diode/resistor but still she doesn't start.  If I remember right we ordered alot of the electrical components from Walcks, so assumed what was there needed to be there.
Any ideas?

T

[p3ferris]

John is right  diodes should not be hot

[johnrb3b]

Three questions:

Does the "thing" in your wiring that is getting hot look exactly like the diode in your second picture?

Can you put an Ohmmeter on the "thing" to see if it has measurable resistance?
A diode would have infinite resistance under one polarity and close to 0 under the other polarity.
A resister would show measurable resistance - the same under both polarities.

Can you get a closeup picture of the "thing" - as close and clear as your picture of the diode?

[Macgraham]

I would check the coil. My Jeep just quit like the key had been turned off and it would not start again until I replaced the coil.Mac

[Carls_jeep]

TomJ, you have two of the things required for it to start. The only remaining is compression so I suggest you do a compression check. You need at least 50 psi and that is marginal and may not start with 50 psi.