Recently checked condition of spark plugs in my 1998 convertible but now get an ignition crackle on the radio. I'm guessing I haven't got one of the coil packs seated properly. Is there a technique for ensuring proper contact between coil pack and spark plug? Also is there a way of determining which one is causing the problem? Thx

 

Usually the HT connector has to seat properly on the spark plug when you tighten up the bolts securing the coil pack as that drags it down onto the plug. You could always loosed the bolts and checked that the coil pack remains seated.

However, I've found that my XK8 ignition interferes with the radio if any any the spark plugs are not quite tightened up enough. I've no explanation for this and have never observed this phenomenon on any other car. Have you torqued the plugs to the recommended figure as that will rule out this issue?

Richard

 

Thanks RichardS, you may be on to something, I did finger tight plus 1/4 turn.

 

You're likely not far out with that. Torque is 4-6 Nm.

 

That can't be right. I agree that's possibly the range the OP is in but I'm sure that there are no spark plugs in any engine which can be left so loose. Around 20 - 30 Nm is the usual range for spark plugs but I'll look in my manual for the XK8 to be sure.

EDIT - The manual for my year XK8 says 25 - 29 Nm.

EDIT 2 - Just noticed the torque setting for the coil pack bolts is 4 - 6 Nm. We're talking about the plugs themselves. 🙂

Richard

 

Thanks guys. Does the torque change between new plugs and plugs that are being refitted? Also, what are your thoughts on using antisieze on XK8 spark plugs?

 

No problem Robin. The torque is the same whether new or old, but I would use the lower end of the scale (25 Nm with dry plugs in this case) just in case the threads have not been treated with respect in the distant past.

However, I always use a light smear of anti-seize and use 20Nm as the factory torques are for dry plugs. I believe that these days all the plug manufacturers, and certainly NGK, say that anti-seize should not be used as the threads supposedly have an anti-seize plating.

Richard

 

My. Bad. Doh! Should've gone to Specsavers.

 

I had exactly the same problem when I changed the plugs on my 1998 XK8 convertible. The plugs were torqued up fine so I took the rubber sheath (?) off each of the coil packs and cleaned up the springs and the contact surfaces. I reassembled and the interference disappeared. I just used a piece of emery paper.