7 replies to this topic

[BaronVonchesto]

So my 76 mini had a battery with low charge. Dad tried to be helpful by charging it up, but then he connected the battery the wrong way round! Positive to ground 

 

He cranked the car for a good 15 minutes before giving up and telling me the car wouldnt start.

 

I've recharged the battery, and connected it the correct way, with the negative to ground. Ignition lamp turns on, but the car wont start (starter motor appears to crank fine as oil pressure rises from zero to 50 while cranking). Suggestions on how to diagnose the problem?

 

Am i correct in thinking i should start by checking that sparks are getting to the spark plugs? Need guidance on what and how to test:

For the spark plug its easy, take a spare spark plug, and connect it to one of the spark plug leads, and ground it on the engine before cranking to see if it sparks. but if it doesnt?

 

Next thing to check i assume is the distributor and the ignition coil. How do i go about checking these?

 

My car uses the standard mechanical fuel pump, so no worries there.

Edited by BaronVonchesto, 24 November 2017 - 04:39 PM.

[Stevie W]

Hi Baron!

Do you have electronic ignition fitted or are you still on points and condenser in the distributor? If you have electronic ignition your Dad’s probably goosed it trying to start your car.

You can check for a spark as you suggest too. You may have also damaged the alternator but until you get the engine started you won’t know if the no charge ignition warning lamp goes out.

Hope this helps!

Steve.

[cal844]

I'd check the points and condenser (replace if the points are burnt) then try again. I have a strong suspicion it's a knackered coil

[BaronVonchesto]

should be points contact on the distributor. is there an easy way to verify visually?

[BaronVonchesto]

So a wire between the starter solenoid and alternator had melted. Replaced that wire, cleaned the contacts in the distributor cap. Sparks at the spark plug were very weak so I replaced the starter solenoid.

 

Now the engine runs beautifully 

 

My guess is that the solenoid was on its way out anyway and my dad's little mistake pushed it over the edge.

 

PS: Mine was a points contact distributor indeed.

[tiger99]

Please be aware that if your alternator has not already failed, it is certain to do so very soon, as its windings and diodes will have been grossly overloaded.

[BaronVonchesto]

Please be aware that if your alternator has not already failed, it is certain to do so very soon, as its windings and diodes will have been grossly overloaded.

Thats a good point.

 

Luckily my alternator is still working, but its entirely possible that it will fail at anytime. Guess I need to have one on spare, or perhaps just change it anyway before I take my mini out for a long drive.

[grck1]

A word of warning, even though your alternator appears to be working it maybe overcharging, as it's quite easy to kill various parts in them by doing what your dad did. Trust me I know lol.
If it is it will boil / cook your battery in short order so I would advise getting the alternator inspected and output checked