Does this plug look normal?
 

I purchased an 86 Carrera last summer with about 85k miles. I had a PPI performed that showed very good leak down and compression. Thought I was in good shape, but oil consumption may be higher than recommended. I say 'may' because I have been chasing a few leaks - return tubes, valve covers, etc. - that have prevented me from getting a good number. Plus, I have only put about 1,800 miles on it since the purchase.

The PO told me that he replaced the plugs just before I purchased the car. Quite frankly, I wasn't smart enough to ask about his oil consumption, but don't know if I would have gotten a straight answer anyhow. I pulled a plug today to see what it looked like. It has 1,800 miles on it, so relatively new.

This is my first Porsche, but have done lots of tune-ups over the years. The electrode (greyish brown) and insulator (fairly white) look pretty normal to me. I wasn't certain about the darkness at the base of the plug, just before the threads start. The dark deposits flaked off when I scratched them with a blade.

I'd appreciate anyone's thougts, I never cease to be amazed at the collective knowledge of this board. Thanks.

http://forums.pelicanparts.com/uploa...1202071519.jpg

The electrode and insulator look fine, so your combustion mixtures are in the neighborhood (not sure what RPM/load you were under before shutting down.) Some oil around the jacket might indicate some cold oil leaking? Do you burn oil? any symptoms you are trying to diagnose?

Thanks for the response. Yes, I am trying to determine if this condition is indicitive of oil consumption. The car is a street car. I do not baby it and it does not see stop and go traffic, but it is also not under heavy loads most of the time it is being driven.

I will get a good read on oil consumption this spring/summer when the weather breaks and I can get it out. I will be shocked if it is not under 1,000 miles/qt and could be lower than the 600 miles/qt threshold. I was hoping the plug may be a telltale sign that might support or not support my concern.

I assume by your response that plug condition can vary quite a bit based on rpm and load. Interesting. I guess that I haven't pulled plugs routinely enough to consider that.

One question. By 'cold leaking', do you mean oil leaking back through the valve guides into the cylinder? I get the customary 'puff' of smoke at start up, but it's gone in a few (2-3) seconds.

Again, thanks for the response.

It looks like the fuel mixture may be on the lean side, or an incorrect heat range plug is being used. Generally, when the insulator tip is as white as this one shown is, it is due to a higher than desired temperature.

Most do not know how to do a plug check..even if you do, with todays gas you may be way off on the reading.

It is hard to tell in the picture, but is it even gapped right?

Best regards,

Michael

I am with Michael on the gap being a little tight. At least it looks this way from the pictures.