HSB

Hi,
I was wondering if you would change the plug wires even if they are in good condition? I've been told by a couple of folks that they change the plugs only and replace wires only if required.

springer3

If you fog the engine compartment with a mist sprayer and see no discharges, the wires are ok and can be left alone. I would have a look under the caps to make sure tracking has not started. While you are in there, clean the crud off the rotor and contacts, but you need not replace parts unless carbon tracks are present.

Wires and other ignition system parts will last longer if the plugs are changed on a regular schedule. Dirty or worn plugs require more voltage to spark. Voltage stress on the remainder of the ignition system ages the insulation and electrical components. The higher the voltage, the more rapid the aging effects. Keep the firing voltage low, and the wires, cap, rotor, coils, and electronic components will last a very long time. Plug replacement and cleaning under the distributor cap is a great example of routine maintenance saving money on repairs in the long run.

Arjan B.

I would leave them how they are, check out the cables for damage and if the connection to the spark plug is clean. You will save a lot of buck here and a lot of work.

Caps and rotors would be a good idea.

Wachuko

I second this approach... at night, turn lights off to be able to see any sparks jumping...

HSB

Thanks guys unfortunately the engine and tranny are sitting on carts in my garage. I will be adjusting valves, replacing plugs, new ps belt and seal, new breather gasket,new rear main seal, new plugs and repainting the tin among other things. The plugs would be easy to replace but I have a hard time replacing something that is working. By the way there is no carbon tracking and I will be using NGK plugs. Fortunately everything but the crankcase to head interface is leaking!--- These leaks are fairly easy to attend to compared to the leaky head syndrome.

PS I found something strange after I separated the transmission from the engine. A small 2cm piece of metal fell out from somewhere. It is shaped like an arrowhead and the two long sides have a slight bevel. Any ideas??

JoeW

Are you recommending to change plugs more often than the Porsche maintenance schedule -- how often do you think is good? Joe W.

springer3

I don't recall the recommended schedule, and a lot depends on how the car is used. Every two years or 20,000 miles, whichever comes first should be plenty often enough. The milage limit is wear/erosion related. The time limit addresses corrosion.

A problem with modern cars is that the electronic ignition systems will fire the plug in oil if necessary. The car runs fine, so there is no way short of an ignition scope to know that the spark-over voltage is getting high enough to start damaging the ignition system. Nobody wants to fix something that is still running fine, but this is one example where the common wisdom (don't fix it if it ain't broke) does not apply.

Wachuko

I replace them every time I do the valve adjustments. Every 15k miles.

JoeW

Porsche recommended 30k. But for most of us, that would be quite a few years in between, & probably better to do it on a more frequent schedule. Joe W