11 replies to this topic

[johng]

Model: Cooper RSP
Year: 1991
Problem:

After getting back from L2B I left the car parked for a few days, then found the battery was completely dead. I tried to jump it but when i connected the final negative lead to the negative terminal, it produced large sparks.

Here's what i've done:

Jumped it off a KA, also 12v (done before, successfully)
The jump leads were the right way around
I removed the mini battery and connected the KA battery up directly, still sparks

Connected negative to bodywork, still sparks
Checked the positive lead tight bend at the battery, no abrasion
Took radio out and checked lights all off
Looked in engine bay, no sign of frayed wires
Earth straps in engine bay are intact

The only non-standard part I've put on recently is a rover 45 radio with all correct wiring, this was on for a week before the run and I had no problems. It's now not connected to the car and sparking still occurs.

Because the sparks are large, I think it's the main cable running from the battery to the starter via the solenoid. Are there any common wear points or rub points that you know of on this cable? Or could it be something else?

Any help is greatly appreciated.

Thanks,

john

Edited by johng, 24 May 2011 - 10:26 AM.

[Carlos W]

Check the under side where it runs along the base of the car for damage, you could try and measure the current draw but make sure you have the meter set high enough as a big short will draw big current

[johng]

Will do Carlos, thanks. I guess i was trying to find a short cut by knowing where any particularly abrasive points are on the cable, probably best to check the whole thing anyway.

[Carlos W]

There was a similar thread a while ago! I'm on my phone but i'll try and have a search

[Carlos W]

I can't find it! Check where the cable goes out the boot, and also make sure your battery isn't fouling on the securing bracket

[johng]

Thanks for looking for the thread and for the help Carlos, I'll check those areas!

[998dave]

Check you've not melted the cable onto the exhaust at the Y-piece, (if running an lcb or aftermarket exhaust).

Certainly sounds like you've a short.

Also, you could disconnect at the solenoid, cover, and check for continuity between the terminals that connect to the car.

Dave

[johng]

Check you've not melted the cable onto the exhaust at the Y-piece, (if running an lcb or aftermarket exhaust).

Certainly sounds like you've a short.

Also, you could disconnect at the solenoid, cover, and check for continuity between the terminals that connect to the car.

Dave

There is an aftermarket exhaust on so that's a possibility, i'll check those two areas and report back. thanks Dave

[johng]

Ok, just got out from under and have discovered a three inch bare section of the cable. It's right at the front of the car on a shelf before it heads vertical up into the engine bay. Looks like its melted away as the rubber at each end is hard and I'm guessing its been like that for a while, as the copper cable had gone green in the centre. It was caked in oil and grime which I think has been acting as an insulator.

Whether this is the only short or not i'll find out when i insulate it and try the jump start again.

Is the only option a brand new entire cable?

john

[SolarB]

Is the only option a brand new entire cable?

Yes. Not difficult or particularly expensive and this is a part of the car you really don't want to cut any corners on.

[bmcecosse]

It would only cause a short if the bare section was touching the body ???

[johng]

It would only cause a short if the bare section was touching the body ???

The 3 inch bare section was touching the metal shelf it was on.