Cooked Ignition Coils

[Wilfred Moore]

I recently visited the Kruger Park. While driving, very hot day, I went through a small puddle of mud water. Shortly after, the engine warning light came on and the Patrol died on me. Trying to start it again with difficulty, the Patrol was misfiring badly. Drove to the nearest camp site, where I had the Patrol recovered on a flatbed back to Pretoria. After investigation, it was found that 4 of the 6 ignition coils were cooked. ( photos attached)
What could be the reason?
In the mean time, Thys fitted other coils and the Patrol runs perfectly.

[jakeslouw]

I'm no expert, but I'd say a combination of age and the water on a hot coil or water on the voltage supply to the coils.
That's why one should only buy TD42 patrols or ZD30 if your name is Reenen.

[Alex Roux]

I'm no expert, but I'd say a combination of age and the water on a hot coil or water on the voltage supply to the coils.
That's why one should only buy TD42 patrols or ZD30 if your name is Reenen.

I did not know this was a risk for coils.
Wilfred, do you think the "puddle of mud water" could have had that effect? I.e. splashed all the way to the top of the engine, to coils?

[jakeslouw]

I did not know this was a risk for coils.
Wilfred, do you think the "puddle of mud water" could have had that effect? I.e. splashed all the way to the top of the engine, to coils?

As far as I know, a short from coil to earth can cause a coil to melt. So in this case, the high voltage went to the head via the side casing, not through the plug.
Path of least resistance.

[Wilfred Moore]

I'm no expert, but I'd say a combination of age and the water on a hot coil or water on the voltage supply to the coils.
That's why one should only buy TD42 patrols or ZD30 if your name is Reenen.

I did not know this was a risk for coils.
Wilfred, do you think the "puddle of mud water" could have had that effect? I.e. splashed all the way to the top of the engine, to coils?

Hi Alex, could not see anything on the coils, there were splash marks on top of the engine and under the engine cover, not much though.

[jakeslouw]

Hi Alex, could not see anything on the coils, there were splash marks on top of the engine and under the engine cover, not much though.

Were the plugs changed recently and are they correct for the coil spec?
Coils will fail if the voltage can't get out of the plug. More than one coil at a time implies a common issue. The only common issue is the upstream voltage (from the voltage regulator) or the downstream circuit : in this case, since this is a coil-on-plug, the plugs are the only common items.

[Wilfred Moore]

Hi Alex, could not see anything on the coils, there were splash marks on top of the engine and under the engine cover, not much though.

Were the plugs changed recently and are they correct for the coil spec?
Coils will fail if the voltage can't get out of the plug. More than one coil at a time implies a common issue. The only common issue is the upstream voltage (from the voltage regulator) or the downstream circuit : in this case, since this is a coil-on-plug, the plugs are the only common items.

Hi Jakes, thanks for your response. I had long life sparkplugs fitted, which was in the vehicle for probably 2+ years, they said it should be changed every 90,000 Km. Thys Ellis has now changed the plugs with normal plugs when fitted the new coils.

[jakeslouw]

Hi Jakes, thanks for your response. I had long life sparkplugs fitted, which was in the vehicle for probably 2+ years, they said it should be changed every 90,000 Km. Thys Ellis has now changed the plugs with normal plugs when fitted the new coils.

NGK PLFR5A-11 or LFR5A-11 as per OEM? As far as I can see, you MUST run a resistor-type plug.

[ChristoSlang]

Makes sense: melting comes from heat, heat comes from excessive current, excessive current comes from low resistance or a short.

[Wilfred Moore]

Hi Jakes, thanks for your response. I had long life sparkplugs fitted, which was in the vehicle for probably 2+ years, they said it should be changed every 90,000 Km. Thys Ellis has now changed the plugs with normal plugs when fitted the new coils.

NGK PLFR5A-11 or LFR5A-11 as per OEM? As far as I can see, you MUST run a resistor-type plug.

The plugs that were in my vehicle: LFR5AP-11 (NGK R)