Points burning out

[Bodger Baz]

Heres a new one on me, switched the ignition on my mates Chevy HUW today and there was a bit of smoke and the smell of burning form the distributor area within seconds, on inspection the points were glowing red hot!

 

the points and condenser were new (NOS) a few months back,its been running fine until today.

 

So what would cause this to happen? a faulty condenser? coil?

 

Baz

[Grumpy]

Sounds like the coil has gone short circuit - Unusual tho

[R Cubed]

Hi Baz, I would think it is the coil shorting out as that is the only link to a positive supply to give enough current flow through the points to earth to get the points red hot :shocked:

Must say I have never heard of that either.

Condenser is only there to cause a back emf to surge the coil to give a big voltage spike to the plugs, and absorb the initial arc at the points.

 

Let us know the outcome.

 

If it is the coil you might want to check the ignition switch ect in case of damage due to high current flow.

 

Just thought, could it be a wiring short with other wires in the same bit of loom as the wire from the low tension connection on coil to points ?

[Richard Farrant]

Did you have to jump start it with a battery start / charger? Reason I ask is that the Chev would be 6 volt ...

[Bodger Baz]

tis strange, its a 12 volt neg earth, no jump starting involved, the coil was new only a few months back as were still restoring it. the low tension wire is a single wire, so cant be shorting on any others.

 

will check the coil first and let you all know.

 

Baz

[Richard Farrant]

tis strange, its a 12 volt neg earth, no jump starting involved, the coil was new only a few months back as were still restoring it. the low tension wire is a single wire, so cant be shorting on any others.

 

will check the coil first and let you all know.

 

Baz

 

So it has been converted to 12 volt in the past then.

 

The only slightly similar problem I have seen, was on a Dennis fire engine with a Jag 4.2 engine. The owner complained that he had to call out the AA on several occasions, when the engine stopped and the points had closed up. I looked at it and noticed it had Lucas Quickfit points, these are the ones that had a red plastic heel. The heel showed signs of melting, this had caused the points gap to close, hence why he broken down, and the AA had reset the gap. I asked what work had been done prior to all this, he mentioned it having an ignition service. Anyway, I investigated further and found that in the distant past someone had replaced the coil, but not with a 12volt one, but a 9volt one which is used on cars with ballast resistors. Originally it would have had points with a hard fibre heel which would have resisted the heat from 12v going through a 9v coil but the newer plastic points melted.

[Bluebell]

Richard even with a nine volt ballast coil, the current through the contact set would not be enough to damage the insulator. The impedance (resistance) across the coil would be too high. The only time I have seen this happen, is when both wires (supply feed, and low tension to the points) were both hooked to the same side of the coil, creating a dead short, when the points are closed. I have never heard of this happening internally in a coil, but all things are possible.

[Richard Farrant]

Richard even with a nine volt ballast coil, the current through the contact set would not be enough to damage the insulator. The impedance (resistance) across the coil would be too high. The only time I have seen this happen, is when both wires (supply feed, and low tension to the points) were both hooked to the same side of the coil, creating a dead short, when the points are closed. I have never heard of this happening internally in a coil, but all things are possible.

 

Bluebell,

It was heat created by running 12v through a 9v coil ( with no ballast fitted), that softened the plastic part of the points whilst it was running this was. Anyway, changed to a new 12v coil and right as rain. Odd things can happen, but sometimes you never come across the problem again, despite sticking it in your memory as something to check for in the future.