Very hot ignition coil

Davedstone

Davedstone

Member
At long last Gene is running and very smooth, but concerned as the new ignition coil is running so hot that you can't touch it. The initial problem was the cable which runs from the tachometer to the + side of the ignition coil was essentially passing heavy current. To cut a long story very short, the culprit was the starting solenoid which was grounding. The cable which burnt was replaced which has taken a long time (unwrapping loom) as the dash had to be removed and cable replaced which runs through the bullhead to the ignition coil.
I also had issues with intermittent tachometer, ammeter and oil pressure gauge which was resolved after removing the gauges and cleaning the contact lands on the back of the gauges to the printed circuit board.
In trying to diagnose the original problem I ordered a new ignition coil which I fitted which brings me to the current problem.
The car runs without any misfiring and at the correct temperature, but very concerned about high temperature of the ignition coil. I also checked the alternator which is also new which runs very hot. The battery is charging which I have checked with my DVM and can see the charging on the ammeter.
As I mentioned, I changed the starter solenoid which has a cold start terminal which carries a cable to the (thicker gauge) + side of the ignition coil. This is used when cranking the engine, thus ensuring 12 vdc is present for easier cold start (cold winter mornings) and when the engine is running, the 12 vdc is then fed via the tachometer.
I decided to pull both cables (white with yellow tracer) off the + side of the ignition coil and check (ignition off) both and the lighter gauge cable which comes from the tachometer has no voltage which is correct as this will only be present when the engine is running. The other cable which comes from the cold start terminal reads 1.29 vdc which is strange as it should (correct me if I am wrong) read zero and this voltage will only be present when the starter motor is being engaged as the solenoid is thrown linking the permanent 12 vdc supply to the cold start terminal when the coil pulls the solenoid to make contact. Now I have replaced the starter solenoid with a brand new one.
Questions: Why is my ignition coil (new) getting too hot to touch. Also my alternator is running very hot (can't hold your hand against it) yet it's charging which is also being shown by the ammeter as charging.
Can anyone help me with this. Never checked the ignition coil before for temperature but Imagine it's not right as running this hot would bring about a breakdown on the coil. The can't be a problem with the alternator as it's charging.

The car is fitted with a lumenition mk12 which was already on the car (no doubt fitted back late 70's) when I purchased this.

Thanking anyone in advance for any help or advice.
https://photos.app.goo.gl/D14juiMv7XGWEBSq6 Showing gauges working.
https://photos.app.goo.gl/nqfQB7EqSX4sCF4s7
 
Check the coil primary resistance - even an ordinary DVM should be able to show the difference between a 3 ohm and one of less than 2 ohm. 3 Ohm should see 12V always, where 1.5 ohm units should only see 12V while cranking, and less , through the ballast resistor, while running. Do you see 12V at the coil lead (detached from coil) , or less? My car should have a ballasted feed, but I see full battery voltage at the coil lead, and the coil measures at 3 ohm. Lucas part no comes up as a 3 ohm type.
 
Thank you for your reply.
The original coil read 1.5 ohms with the new coil reading 1.4 ohm. With the cranking lead off from the + side of the coil reads 12 vdc which is then removed when the engine runs with the just under 12 vdc from the tachometer. So the cold start terminal supply is doing it's job only when crakning the engine.
There was no ballasted resistor and nothing has changed since owning the car. The burning of the wire was due to the starter solenoid having a short on it, so replaced the solenoid so starting shows the correct voltage with no current being drawn excessively has been removed. The 12 vdc from the starter is correct and only present when cranking the engine.
Perhaps as an exercise, fit back the original coil and see what happens.
Also an area of concern is the high temperature on my alternator. I expect it to get hot as it's generating current and runs the same temperature as the top of the engine rocker cover. Is this normal? Is there some connection do you think?
 
With a 1.5 Ohm coil, you should NOT see +12v at the coil connector unless cranking. I have seen mention that in some cars the ballast resistor was built into the loom, not a separate visible item. With 12v at the coil it could consume 8A, which would not do the wiring any good. Strongly suggest that you either fit a ballast , or a 3 ohm coil. This MAY account for your alternator running hot, but it might also be an unrelated problem - a poor earth somewhere might do this , especially at the battery - undo, clean, refit the earth there. My car sounds the same - 12V at the coil lead (disconnected), no signs of a ballast, but a 3 ohm coil (Lucas DLB101) - runs fine, starts well.
 
Davedstone said:
the just under 12 vdc from the tachometer.
Click to expand...

Turn the ignition on, don't crank the engine, just measure the voltage at the +ve side of the coil.

As JP says, it sounds as if the ballast resistor has been removed and you are running a coil designed for a ballasted feed with a full 12V
 
Thanks quattro for your reply.
I've come to this conclusion now. Yes, I metered the 12 vdc from the cold start which once started goes to zero with the remaining 12 vdc being fed from the tacho. I know some earlier P6's had a ballast wire and some did not even have this. The coil I purchased I thought was for an un-ballasted classic car and it's not, so now I will order the ballast resistor.
 
jp928 said:
With a 1.5 Ohm coil, you should NOT see +12v at the coil connector unless cranking. I have seen mention that in some cars the ballast resistor was built into the loom, not a separate visible item. With 12v at the coil it could consume 8A, which would not do the wiring any good. Strongly suggest that you either fit a ballast , or a 3 ohm coil. This MAY account for your alternator running hot, but it might also be an unrelated problem - a poor earth somewhere might do this , especially at the battery - undo, clean, refit the earth there. My car sounds the same - 12V at the coil lead (disconnected), no signs of a ballast, but a 3 ohm coil (Lucas DLB101) - runs fine, starts well.
Click to expand...
jp928 said:
With a 1.5 Ohm coil, you should NOT see +12v at the coil connector unless cranking. I have seen mention that in some cars the ballast resistor was built into the loom, not a separate visible item. With 12v at the coil it could consume 8A, which would not do the wiring any good. Strongly suggest that you either fit a ballast , or a 3 ohm coil. This MAY account for your alternator running hot, but it might also be an unrelated problem - a poor earth somewhere might do this , especially at the battery - undo, clean, refit the earth there. My car sounds the same - 12V at the coil lead (disconnected), no signs of a ballast, but a 3 ohm coil (Lucas DLB101) - runs fine, starts well.
Click to expand...
Thanks JP.
I will order a ballast resistor and hopefully this will also take care of the alternator. I timed the time it took to get to what I feel is too hot which was about 6 minutes. As soon as this arrives I will fit and give feedback on coil and alternator. :eek:)
 
Davedstone said:
Thanks JP.
I will order a ballast resistor and hopefully this will also take care of the alternator. I timed the time it took to get to what I feel is too hot which was about 6 minutes. As soon as this arrives I will fit and give feedback on coil and alternator. :eek:)
Click to expand...
Fitted ballast resistor which rectified the problem of the coil over heating and within minutes I could smell petrol, so quickly checked rear tank for any leaking fuel on the ground and then quickly checked under the engine and nothing so very concerned turned the engine off and checked around the carburetors to discover a lot of petrol over the exhaust manifold leaking from the second float chamber lid...whatever next!
When will this end. Ok, the car had not been used in over 8 years, but it seems not to want to ever get back on the road.
Now, what type carbs are these and where does one get joint washer for float chamber. I assume these are HS8 type. Can anyone advice or help in directing me to a supplier of jointing gaskets.
 
Well mine needed all new brakes, a new automatic gearbox a steering idler, various suspension rubbers, rebuilt carbs, a new radiator, new ignition system, new distributor, new fuel pump, replacement camshaft, new wheel bearings, new UJs. And i still have a seemingly incurable steering issue which I suspect will need a new steering box...

So no, not "minor" in my case. And like you my HS6 leaked from the bottom of the hose from the float chamber filling the V with fuel.
 
PeterZRH said:
Normal when recommissioning a long unused car. Mine came back after 11 years. I'll never do this again.
Click to expand...
Yes the list is endless. I know that no doubt as and when I actually get to drive some miles, more things like brakes etc will show problems. The great thing about having a car like this is parts are pretty much still available. Of course as one works on the car, the more one learns about it and since I like doing things technical, I do enjoy working on it, but would like to see the fruit of my labour rewarded by actually driving it...
 
Oldskoolrob said:
Ah the joys of resurrection. Mine came out of a 20 year slumber, lots of little teething problems like that.
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20 years! that's incredible. At least corrosion is not an issue with such a dry climate. Mechanical work I am able to do, but not bodywork which was the main reason when I saw this car, I made the decision to buy just on spec from the pictures and the fact it had been stored in a dry garage for 7 years almost guaranteed a rot free body.
Since I have owned this which is just over 2 years I have had the radiator re-cored, fitted a new alternator, battery and replaced the gearbox (would not select 4th gear) replaced the clutch, pressure plate, replaced burnt cable, fuse box (inside the glove box) dashboard switches, ignition coil, starter solenoid and now waiting for float chamber lid gaskets.
I have removed the dashboard, removed all the gauges, cleaned the printed circuit board lands (contact for gauges) had the gauge/dashboard shot blasted and etched primed this with two top coats of silver, not that anyone would see this, but I could not put this back rusted. I am sure there will be more to do. It's an endless project of joy and frustrations, not to mention money...which I don't with my partner...lol!
That famous day of collecting it with my friends trailer.
Interesting fact was when I was pulling this behind my friends van, I couldn't but help notice how many heads were turning, maybe from curiosity as the shape is in my eyes classic...a gentleman's car,
 

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Gaskets in contact with petrol will dry out and never recover when stood dry for long periods. Carb service kits should restore all the relevant parts to new. Might be worth checking the state of the throttle shafts before ordering - service kits might not include shafts, but the Rebuild kits will. If HS6 type, the jets will need new seals, HIF6s will need new choke Orings and shaft seals.
Good luck...glad the coil thing is resolved.
 
Davedstone said:
Yes the list is endless. I know that no doubt as and when I actually get to drive some miles, more things like brakes etc will show problems. The great thing about having a car like this is parts are pretty much still available. Of course as one works on the car, the more one learns about it and since I like doing things technical, I do enjoy working on it, but would like to see the fruit of my labour rewarded by actually driving it...
Click to expand...

That's the insidious part of recommissioning and old car. Seals and gaskets dry out and shrink and they might be OK for a while but any time in the next 1000s of miles you can expect some failure. And things that suffer due to age don't necessarily fail in logical, easy to diagnose way either.

I'll likely never own and improve another old car again, but if I did, I'd pick a scruffy but solid regularly used one for improvement and leave the barn finds for someone else.
 
jp928 said:
Gaskets in contact with petrol will dry out and never recover when stood dry for long periods. Carb service kits should restore all the relevant parts to new. Might be worth checking the state of the throttle shafts before ordering - service kits might not include shafts, but the Rebuild kits will. If HS6 type, the jets will need new seals, HIF6s will need new choke Orings and shaft seals.
Good luck...glad the coil thing is resolved.
Click to expand...

Another thing as well, the new kits for SUs from Burlen have rubber components designed for ethanol fuel. Recommissioning an old car you will likely find it will run fine for a few 1000 miles and then leak and the change from a small weeping to a full on torrent will be very rapid. Usually at the least convenient time. So I'd say a carb overhaul, like new brake hoses is not an optional job. As has been noted leaks are not so bad on a 4 pot because the fuel just leaks to the ground. On the V8 it forms a nice, flammable puddle in the V! Similarly, swap the fuel reserve tap o-ring for a viton one. It's a £2 job but gives you the reassurance.

I think a "recommissioning" thread might make a good sticky actually.

Another essential, get a fire extinguisher of enough capacity to deal with potential fires.
 
jp928 said:
Gaskets in contact with petrol will dry out and never recover when stood dry for long periods. Carb service kits should restore all the relevant parts to new. Might be worth checking the state of the throttle shafts before ordering - service kits might not include shafts, but the Rebuild kits will. If HS6 type, the jets will need new seals, HIF6s will need new choke Orings and shaft seals.
Good luck...glad the coil thing is resolved.
Click to expand...
Thanks for your reply. So it's wise to order a complete kit then? I have the "Rover 2000-2200" Repair operations manual which shows all the various carbs used across the entire range of engine configuration and according to my manual the carbs are HS8's not HS6 type.
PeterZRH directed me to Burlen's so I will look to see if I need anymore parts.
Next concern are the brakes. So I will drive with caution for the first 10 or so miles and remove wheels to inspect for any signs of leaks, or just order new cylinders?
 
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