Melted engine ground wire - help!

[Pedro]

Was driving along , some smoke started coming out if the engine bay and then the car stalled.

 

The main ground wire (from the valve cover to the car body) was melted (all the plastic melted off and the wire itself is left there).

 

What could have happened ? Looking for any help on this one.

 

 

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[neRok]

Too many amps for the wire to handle, thats why they melt. The question is, where have these extra amps come from? Have the battery or main power wires come in contact with the body/engine?

[Scoota G]

I would say the main negative lead has come loose causing all the power to be redirected to the smaller lead overheating it. I have two main leads to my engine from the negative.

[Zedman240®]

Check if the alternator hasn't shorted itself internally. For the car to stall, something tells me something big has let go.

[nizm0zed]

Check your battery earth, both at the block and the terminal for a good solid connection.

Some failure has caused a large current to direct through that wire.

[Six_Shooter]

The body ground on my car is attached to the battery.

 

I wouldn't be looking at the alternator or really anything engine related, as long as I understand how your grounds are attached. It sounds like you have a ground from the battery to the engine block (near the starter/bellhousing area), and then another ground lead from the cam cover to the chassis? The vehicle would shut down due to having a high resistance current path, this does not automatically mean that the alternator has failed, there are a few systems that involve the chassis wiring to support the engine running as well.

 

Do you have any additional electronics installed?

 

Check that both ends of the ground lead are tight, and that all other ground leads are also tight. A loose ground connection can cause a high rssistance and excessive current to pass on that wire.

[Wayne G]

What Scoota said.  Your main earth not working

[Zedman240®]

I doubt a running car draws around 300 amps. There's a big short somewhere.. I'd start at the alternator and work back.

[Pedro]

ok. thanks for the tips. the culprit was that the positive terminal was touching the bonnet (just) as the battery was chocked up so that the original battery clamp could do its thing (physical battery was obviously a little shorter than the factory one.

 

i have now sorted it out with a smaller chock under the battery.

 

thanks again!

[neRok]

10 points for me

 

Why not fit a new power wire so you dont need to 'chock' the battery at all?!