My 89 xjs is in need of some new spark plugs. I have changed plugs before but never have I seen plugs so hard to get to. Is there a trick to getting to these things? Is it really as hard as it looks?

Submitted by mr442nt@wideop… on Mon, 05/01/2006 - 10:48

To make your life easier, in addition to removing the cruise control, loosen the AC compressor belt and unbolt it from it's brackets. You do not have to disconnect the lines. By doing this, you can move it around enough to access the plugs with a standard plug socket. For the rear four, unbolt the throttle tower (pop off the linkages first) and lay it back away from the vally towards the firewall. It's held on with four nuts. Trust me, taking an extra 20 minutes to disconnect this stuff and move it aside is well worth the effort. My first plug change took four hours (including a trip to Autozone when I broke the 12th wire, a lot of cursing followed). It would have been a lot longer with everthing still bolted down.

And as Steve mentioned, use anti-seize. It will make the next go around so much easier. Lastly, clean the valley with compressed air. DO NOT LET ANYTHING, NO MATTER HOW SMALL FALL INTO AN OPEN PLUG HOLE.

Have fun!

Tom Kipp
89 XJ-S Coupe

Submitted by NE52-32043 on Wed, 04/26/2006 - 14:31

Richard,

The answer is yes and no. I did it several times on my old '89 XJS. The trick, I found, was using a long extension on the ratchet, with a universal swivel between the extension and the spark plug socket. The hardest part was removing the plug wires, and worse, putting them back. I always started at the rear on the A bank and worked my way forward. Getting in between the AC compressor and the front plugs is a bit interesting also.

It also helps if you have a spark plug wire puller. And for reinserting plugs, attach an old spark plug boot to a piece of thin dowel; or use a length of garden hose. You'll never cross-thread a plug. Screw the plugs in as far as possible by hand to avoid stripping the threads. And use anti-seize on the threads so you can get them out again. I always used NGK plugs. They worked great in the XJS.

And be sure you gap the plugs exactly to spec. (.025", if I remember correctly). Do not open up the gap to get a "hotter" spark. Especially with the Marelli ignition, but also with the Lucas, it is not recommended.

On additional thought -- if your cruise control doesn't work (most don't), remove it. It makes working in the engine V much, much easier. And check the wires and distributor cap and rotor, while in there. If you replace the distributor cap, make sure it is the vented cap, and make sure it is connected to the vacuum line.

Steve Weinstein, JTC-NJ
'70 XKE FHC, '69 XKE OTS
Former '89 XJS Coupe owner