87' XJ6 cranked and idled, after ~1 min, white smoke appears from the connection mounted to coil. What is this? Has (2) white wires connected. Smoke originates from within the bracket surround whatever this connection is.

 

Hi Rwgaddy,

Looks like a ballast resistor.

White smoke? not good, but looking at other connections in your pic ie. fractured boot on injector in foreground suggests general maintenance isn't up to what the British call 'snuff'.

Ballasted systems use a different resistance coil to unballasted coils.

Cheers,

Nigel

 

Thanks Nigel. I'm working my way through the entire car as it has sat for the better part of 16 years. What would be causing this? I'm not confident in my understanding, what does a ballast resistor do? Would it be in my best interest to replace with a coil that has an internal ballast resistor or could the problem be the coil itself? Maybe another component upstream? Sorry for rapid-fire questions, hoping to learn a thing or two here. Many thanks!

 

Were it my car, I'd just ditch that resistor. The 87 car uses an electronic ignition system. The Ballast resistor dates back to "points and condenser" ignition. Designed to pride lower volts at times to protect the points from rapid deterioration.


The smoke is far from normal and signifies trouble.


Carl

 

Carl, I cranked again to see if smoke would clear (burn off any contaminant) and monitored the coil. The coil never warmed, the smoke came back and seemed to dissipate but not completely (became very minute and almost none). Car idled down just fine, again coil never overheating. Any thoughts?

 

hi had to register to reply to this thread.!!!!!!!! usually just like to read these things but had to add that the resistor lowers the voltage to around 9 v by converting some of the voltage to heat. check that you have at least 9 volts at the coil + to much resistance and the voltage would be lower hence more heat.
If your car has no points chuck the coil and resistor out and grab a new coil that uses no resistor and your spark will be greater hence better combustion and better fuel economy. I come across this alot as a mechanic. not a lot of younger guys have ever even seen a set of points. got my first jag about a year ago out of a junk yard for a grand. 94 xj 12 6ltr. / (120k kilometers. got the motor dialed in but I'm unfamiliar with these beauties. i believe the gold jaguar badge means it's a 305 if anybody could confirm this it would be greatly appreciated.

 

oh if you just ditch the resistor the oil in the coil will boil and burst. its designed to operate on 9 v. a new 12 v coil from any gm product is about 20 bucks and will work great with electronic ignitions

 

Nearly EVERY one I have seen (when I worked on these daily) smoked when the French made coil (Unipart) started leaking oil. Sometimes they just smoke when there is no leak!!

Look closely at the wire terminals and the High Tension lead connector.

I would not worry about it if it is not leaking.

bob

 

How hot should coils get? Should they get"too hot to touch?" The coil in my XJ6 with no resistor gets so hot I can't put my hand on it very more than a second.

 

Not good in my opinion. Heat denotes high electrical resistance. Electronics do not like heat. Not good.


Carl

 

Is your car supposed to have a resistor? If so, there's the cause of the hot coil.

 

The BALLAST resistors were installed on the UNIPART coils.
They are just a wound wire resistor that gets HOT as a normal function.
The coils get WARM when operating (and sitting on the engine) as do most electrical things.

bob