Friends, I have started the car a dozen times in 20 degree weather before I decided to post this one. Seems to hold true. Let me explain:

We have had several threads over the years discussing the rattle sound the XK8 makes for a few seconds after start up when cold on very cold days. I have always had this happen, here's the finding - After I changed the spark plugs it went away!!

I can not explain this, all I can figure is that the irrudium plugs at 0.052 gap made the difference, or something in the air intake tube was corrected during the reinstallation after changing the plugs on that side. I haven't done anything else. I'm leaning towards the plugs, but can't think of a good logical reason - so like they say use if you choose it. (FYI - the plugs were 70K miles, gap 0.042ish and corroded looking). I hope this holds true and helps you too.

Wondering out loud - Could the noise have to do with computer actions taken when she doesn't start in a very cold environment within some fraction of a second time parameter?

The ignition certainly fires a few seconds earlier now that the plugs are in. Following this logic, could there be behind the scenes monitoring/action that kicks in affecting some parameter that produces the noisewhile running, but whose primary mission is to help to get it fired up due to both the cold and the cranking time? This could then self correct seconds after starting eliminating the noise - which describes what we hear (obviously brainstorming take it for what its worth).

 

John, Did that give you a headache. LOL
Sounds good to me.


Wayne

 

LOL - almost a migraine, but we do develop a tolerance with these cats don't we?

 

Did you find one o the plugs was loose when you removed the old ones?

 

Great question, but no - for sure they were all nice and tight.

 

When I first posted this post about solving the rattle, I was admittedly questioning myself. As we noted above, it is hard to explain, but since then, I've had more than 6 starts on a winter morning in the last week, with temperatures below 15 degress F, It always used to rattle. I am now convinced - The rattle is gone!

Changing the plugs wasn't a quick job on these babies. Rev Sam's video is helpful but for the record, the 1998 XK8 has a little different spark plug access set up.

I meant to share these findings earlier, may help someone with a 1997 or 1998 XK8:

Do yourself a favor: Get hold of a 2 inch ratchet extension. It is invaluable for this job. The Spark Plug access cover is held on with 9/32 inch bolts. It is cramped access, but with my fat fingers if I could do it so can you.

It doesn't look like it, but every single one of the 8 bolts securing the acess cover are accessible with the 9/32 ratchet, most with the 2 inch extension.

Driver side USA : You will need to unbolt the coolant overflow tank, and the device next to it with the vacuum hoses (don't know the name). Neither of these items need to be disconnected from any hoses, just push them aside gently.

Passenger side: Like Rev Sam shows, you remove the air intake assembly, 3 bolts.

The wire clips that attach the wires to the ignition module are tricky. I had no problem getting them off in cold weather (= brittle) on the drivers side. The clip retainer access is at the top of the connector driver's side. On the other hand - the passenger side is reversed, so the clip release is on the bottom. I managed to break 3 of the 4 clips off with little pressure. So, it's a heads up don't do it if you can...

Of course you can imagine my thoughts: "it just took 30 or 40 mintues to get the access cover off, how long will it take for these connections to shake loose in the future, what will that cuase. . . that's all I need.".

Well I couldn't live with that possibility and looked at things more closely. Here's a good fix if you ever do the same thing.

Now that you broke the "tab" off, this creates a clear channel along the black electric connector to secure a fastener. It would be faster/easier to use a wire, but I couldn't risk throwing another piece of metal (the wire) in the mix that close to the coil and all that voltage. As Tesla would have told you, strange things happen with 40 or 80,000 volts.

I have plenty of small thin wire ties - they work perfectly. Take 1 wire tie, create a loop through the black electrical connector where you just broke off the plastic tab, and connect this wire tie to itself. Now you have a loop on the connector.

The far side of the inition coil has plenty of space between the rectangular metal housing, and the insulated wire coils inside of it. Take another wire tie - thread it through the space between the metal rectangular bracket and the insulated wire coils inside it. Connect the wire tie to itself forming loop #2.

There is enough room to secure these two loops to each other with another wire tie. Position this wire tie's connector so it doesn't/can't rub on anything. It all can fit nicely without any stress points that may someday rub through insulation.

It works great. It took me 2+ hours of experementing to come up with this, hope it helps you now.