Spark Plug Issue

[Andyni]

Thanks to Pammy I replaced my air filter and spark plugs today. The spark plugs are causing some concern. All plugs were apparently changed by the main Mercedes dealer about 12 months ago. The old plugs look like the picture attached.

This type of damage is caused 'due to the effects of corrosion, oxidation and reaction with the lead in petrol' according to spark-plugs.co.uk but as I have only used unleaded petrol it can not be lead.

I had exclusively used Tesco’s fuel until two months ago. Has this been the problem??

Andrew

 

[grober]

Have you got the correct heat range plugs fitted? I don't know what your new ones look like but there appears to be a degree of electrode erosion there. Can be caused by timing too advanced / weak mixture / fuel octane too low etc. wonder if they really were changed the last time? were they gapped correctly? What was the old plugs make/number? A picture of a new plug for comparison would have been useful. I'm sure other 4 cylinder petrol w210 owners would be able to shed more light than me.

 

[TVRTASMIN]

As Grober has indicated, they were probably not change by your stealer at the time of service.
You will be surprised at how much doesn't get done.
My '95 E300D had a really dirty air filter which should have been changed at a previous service as the car has only done 105K with full MB service history.
I think the majority just change the oil and filter, as this is easily spotted by the customer.
Those plugs look well worn to me.