Hello!
I'm new to this forum, but I have a question about reverse polarity. I inherited a 64' mk II jag from my grandfather and I'm trying to get it running. I had it sent to a reputable shop where they made the car "drivable". When the work was complete, I drove the car about 110 miles when it started smoking out the freeway from the exhausted. I pulled over and noticed that the battery was hooked up with the positive ground cable connected to the negative battery terminal. Does this sound right?

 

it probably is still wired Positive Ground as they came originally from the factory.

you can convert the electronics to Negative Ground easily. Click the following link to learn how: Star Auto Electric Company - Instruction For Polarizing Generator

otherwise I doubt the smoke has anything to do with the way the battery is connected.

is the smoke white? Check the radiator cap and look to see if you see oil mixed with coolant, that is a sign of a bad cylinder head gasket.

Also check the Heater Valve to see if it is leaking coolant into the exhaust system.

 

Thanks for the info!

Sorry I should have been more specific with what happened.

When the car started smoking, I pulled off the freeway into a gas station and let the car cool down then started checking the fluids. There was maybe one drop of oil left on the dip stick. I'm guessing the reason the car was smoking to begin with was the low oil level. I added 2.5 quarts. Then I tried to start the car, but it wouldn't even turn over (just heard the clicking sound from the starter). Also noticed that the fuel pump wasn't clicking anymore. Decided to try to jump it, but noticed the battery might have been hooked up wrong since the positive ground cable was hooked up to the negative terminal of the battery. I turned the battery around and tried starting the car again and it started up really nicely and pulled forward a couple feet so I could put gas in the car. I tried starting the car again and it wouldn't turn over like before only heard the starter clicking. Tried to jump start the car and it turned over, but I think the fuel pump stopped working so it wouldn't fire.

So, I'm trying to figure out what's going on. I drove about 110 miles straight with the battery hooked up with the positive ground cable on the negative terminal of the battery. When I turned the battery around, the car started fine, but then maybe the battery was actually hooked up correctly to begin with and I burned out the fuse after switching the battery which is why the fuel pump stopped working. The mechanic that worked on the car told me that the car would not have been able to go 110 miles with the lights on if the battery was hooked up the wrong way, but I don't know much about this at all so I wasn't sure if that was a true statement or not. I want to figure out which way the battery should be hooked up before I start doing anything else. I don't want to damage the charging system. I'm starting to think that maybe the car was already converted to negative ground and I just wasn't aware of it.

Any ideas?

 

I don't understand what you mean when you say:

".....with the battery hooked up with the positive ground cable on the negative terminal of the battery".

What do you mean by "positive ground CABLE" ? It is either the ground cable or the positive cable, but not both.

let me illustrate it like this:

any Cable or Strap which is bolted to the body or "chassis" and then connected to the NEGATIVE POLE of the battery, equals NEGATIVE GROUND.

any cable connected to the body or "chassis" and then connected to the POSITIVE POLE of the battery, equals POSITIVE GROUND.

These cars, the MK-1, MK-2, S type, and 420, usually have a ground strap or "cable" bolted to the body metal near one of the hood hinges. It can be connected to either battery pole, and that is what makes the difference between Positive or Negative GROUND, or like the English call it, "Positive or Negative Earth".

do any of the electronics stopped working when you switched cables?

the Voltage Regulator might have been damaged, if not the Generator when you switched poles and cables, because in order to do that, you must first re-polarize the electric system.

 

if the conversion to negative ground has been done correctly then when you hook up the battery this way then the ammeter pointer should swing to discharge with the engine not running. - if it swings over to charge then the car has not been converted to negative earth.
These cars were originally made positive earth so thats a good starting point.
I have had the same problem where a "restorer" assumed the car was negative earth and connected the battery the wrong way - the pointer indicating "charge" on the ammeter when switching on without the car running (this should swing to discharge). If you have changed the battery around then you probably wont now do any further damage so you could check the polarity configuration before going any further. Check all fuses while you are testing.
The smoking may be from a different problem .
I have spent hours bringing the electrics back to life.
A good indicator is the ignition light -that should go out when you increase the engine speed. If you have set the polarity correctly and the light stays lit then the generator may need re-polarising or replacing. Checking the voltage regulator can also be advisable.

 

Thanks for the clarification. That was helpful. I'm not sure if the car is currently negative or positive ground at this point. That's what I'm trying to figure out.

What exactly is included in the electronics? When I switched the battery, the only thing I noticed that was different was the fuel pump not working. All the lights work after switching the battery (they were working before too).

 

I turned the ignition switch on and the ammeter pointer remains in the center between C and D so I'm not even sure if the gauge is functional. Is there another way I can check if the car is positive or negative ground? Thanks so much for your help!

 

If you are unsure as to the polarity, follow the procedure for polarising the voltage regulator assuming the regulator has not been damaged.

Once the vehicle has been polarised, assuming you desire negative earth, remove or cover over any labels that indicate the vehicle has been wired with 'Positive Earth' so there is no repeat of confusion.

 

Turn on the ignition switch again and turn on the headlights.
The ammeter should show a discharge D, if the polarity is correct.
If it moves towards the charge side with the headlights on, the polarity is incorrect.

 

I tried this (turned on the ignition switch and turned on the headlights but the ammeter pointer still stays in between c and d. It doesn't move at all so it looks like the gauge itself isn't working. is there another way I can check that the car is hooked up properly to the battery?

 

does the pointer go back to zero when you remove the ignition key? or does it stay at the center?

As for checking if the battery is connected correctly, you wil need to re-polarize the system as suggested above. No other way around it.

does the Starter crank the engine at all ??

 

Hi
It sounds as if your ammeter is not in the circuit or broken
There should be some movement.
Its not a definitive check but you may find that on the battery - the positive terminal is slightly larger - if the earth cable fits this terminal then its positive earth. If the earth cable fits the negative battery terminal better - then its probably negative earth. The cars were mainly positive earth but I found that some restorer just assumed my car was negative earth and swapped the brass connectors round so he could fit the battery negative earth and promply blew up the voltage regulator box, radio, clock, fuel pumps and the washer pump was going backwards so not working very well at all. Wipers and horns didnt work and the ammeter went backwards. I had to fit the battery positive earth and re-polarise the generator. There were blown fuses and corroded fuse holders - so problems were not only down to polarity reversal.
best of luck

 

Sounds like the engine is your biggest problem !! 2.5 quarts is a lot of oil to add after 110 miles. It sounds like engine rebuild time.

 

Jose you rock! I now understand that it is an easy process to reverse the polarity. Let me explain:my negative (black) cable is grounded to the frame while my positive (red) cable is connected to the electrical system (just above the engine) my electrical system appears to be working fine (although I am not currently running the car as I am replacing fluids and flushing systems). When I turned my headlights on I saw the ammeter move to the left and thought it was draining the battery-but C is on the left and D is on the right of my ammeter (is that standard?). So if I reverse the polarity as instructed the electrics should still work but the ammeter will correctly move towards D? Lastly we very quickly reversed the cables and the lights would not turn on. There is no plate or sticker to indicate that the reverse polarity has been reversed.

 

Hi can I advise you to approach the electrical problems logically and start at the beginning. Sorry if you find this condescending - I dont intend this but I also dont know how much (or little) you know - so I'm starting with the basics.
The polarity of the car should not affect the lights - they should work either way.
Fully charge the battery - lets assume at this point that it is positive earth.
Find the + on the battery and connect this to the cable attached to the body of the car.
Then attach the -ve terminal on the battery to the cable that goes to the starter solenoid. At this point - if you turn on the lights and the ignition (without the engine running) you should see the ammeter swing towards D for discharge (please make sure the battery is fully charged before hand)
The red ignition warning light should be on
If you can start the car then the ammeter should swing towards the C or charge position and the red ignition light should go out - you may have to increase the engine speed slightly to achieve this. - Please check that the fan belt is on, tight and driving the generator pulley - if the red light stays on the you may need to re-polarise the generator - if after doing this there is still the red ignition light on with the car running at say 1500rpm then there could be a problem with the generator. The car will now be positive earth - you will probably need to buy an original radio - some of these can be + or - earth switchable.
You may find damage with petrol pumps, dashboard clock in the rev meter (although these never worked and I have modified mine with a digital battery driven one),wiper motor,radio,and possibly the voltage regulator (I replaced mine just in case) The ignition ciircuit should be OK and the screen washer pump should work - in the correct direction. hope this helps.
Its always difficult when you seem to have several different problems at the same time as sometimes they seem to be coincidental or linked - always best to tackle one problem at a time. Get professional help if you dont understand these things. Its easy to get totally confused when you dont know. I would also check all the fuses and clean up the fuse box and connections - clean and tighten the fuse clips.

 

oh and by the way - get a sign to say this vehicle is positive earth and stick it near the battery - I am working on several cars most of which are negative earth - I need to keep reminding myself that the Jag is different - I have nearly made a mistake until I stuck a notice on to remind myself.

 

All you guys are funny.......Kiddouglas seems to be a millennial.
I have your correct fix......sell the car and buy a HONDA ACCORD!
Sadly I will be right.....
To all the old timers on this post, I couldn't understand one sentence he was saying, how you guys can conclude a fix is funny......
All in fun.
GTJOEY1314

 

Hmmmmm
Honda accord eh!
Personally I think the philosophy of the classic car enthusiasm lies not with your every day transport answer but in the fact that - if you can - then do.
The sense of achievement when you have resurrected another classic car destined for the breakers yard is immense.
I'm halfway through my 66 S-Type resto and enjoying the challenge it throws at me along the way - I like puzzles and sorting stuff. I enjoy feeling clever when I make something work.
I have had an unusual fault with my RHS petrol supply.
It appeared that the pump wasnt working so I sripped and refurbed the pump - tested on the battery OK but when connected to the tank - it stopped.??
Fault turned out to be that after standing for over 20 years the fuel in the tank had turned to tar - when I put fresh fuel in - the tar softened and blocked the supply pipe - the suction pressure then stopped the pump.
Just goes to show how a fault in one place can manifest itself elsewhere.
I now need a new tank or need to clean all the old tarry petrol sludge out.
Interesting - yes you wont get this problem on the accord.

 

You'll get the problem with the Accord if it sits for 20 years.
Fuel injected vehicles are dreadful, they're great when nothing goes wrong ( and you notice I so "when" and not "if")
When something does go wrong, it's like trying to find a needle in a hay stack most of the time.
If you leave a fuel injected vehicle sit too long you don't rebuild the fuel pump, you get a new one and possibly new injectors _ very expensive.


People can have their modern fuel injected cars.

 

Yes - I agree
I bet they as rare as hens teeth in 20years time only seen in pictures -parts ? Just dont think about it. My 66 S Type will still be driving around.