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Changing Spark Plugs Coil Over Plug


curiousB
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Any special advice before I go swap all 8 plugs on my 2004 LS430? I just rolled over 105,000 miles. The originals have been their since its birth in summer of 2003.

A few questions:

1) Any special methods to remove the Coil Over Plug (COP)? I suspect the plastic COP assembly has gotten a bit more brittle since 2003. Also wondering if the rubber boot is stuck tight to the plug will the COP snap into pieces. I presume gentle twisting action is best but at $100+ per COP I don't want to damage any.

2) What about spark plug socket. Wondering if I should sacrifice a 5/8" spark plug socket and extender and tack weld together so the extender doesn't come off the socket after I torque the new plug in.

3) Dielectric grease on new plug and boot upon reassembly or don't bother?

4) Anti-seize compound on new plug threads?

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Twisting the boot/connector is always a good idea. I prefer my Snap-On magnetic spark plug socket - expensive, but it holds the plug perfectly and releases cleanly without yanking the socket off the extension. If you are worried about the socket coming off the extension, just wrap the two together with duct tape.

A bit of di-electric grease is a great idea - it's pricey too, but worth using. And a bit of silver Never-seez on the threads, just back from the end will make the next time far easier.

I think you have it covered!

SRK

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Any special advice before I go swap all 8 plugs on my 2004 LS430? I just rolled over 105,000 miles. The originals have been their since its birth in summer of 2003.

A few questions:

1) Any special methods to remove the Coil Over Plug (COP)? I suspect the plastic COP assembly has gotten a bit more brittle since 2003. Also wondering if the rubber boot is stuck tight to the plug will the COP snap into pieces. I presume gentle twisting action is best but at $100+ per COP I don't want to damage any.

2) What about spark plug socket. Wondering if I should sacrifice a 5/8" spark plug socket and extender and tack weld together so the extender doesn't come off the socket after I torque the new plug in.

3) Dielectric grease on new plug and boot upon reassembly or don't bother?

4) Anti-seize compound on new plug threads?

1) I wouldn't worry about the coils. They are very durable. The only thing to be concerned with is the wire connectors that plug on to the coils. That's the part that gets brittle. If one of the locking tabs should crack when you squeeze it, don't freak out. I use a dab of FIPG (Toyota's Form In Place Gasket) on the OUTSIDE of the connector so it doesn't vibrate loose. I suppose you could use any RTV Silicone, but I have an unlimited supply of FIPG. Yes, if necessary, a little twisting and pulling should release the coils.

2) I use a Snap-On 5/8" spark plug socket with a built-in u-joint and a locking 3/8" extension. You could get away with wrapping electrical tape around the socket/extension so they don't pull apart.

3) Dielectric grease? Not a bad idea, I suppose. I never do.

4) Anti-seize compound? No. Just make sure they are started in the hole straight and snug them down the rest of the way.

BTW, I just checked the maintenance schedule for the '03 LS430 and spark plugs are not required until 120,000 miles. If you do decide to replace them, DO NOT use anything else except for what is called for by the manufacturer(Denso iridium spark plugs) or you WILL notice a difference.

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I know I am a tad early on the plug change but I've been battling a Catalytic Converter problem and wanted to see if the plugs look clean or do I have one cylinder fouled and contributing to my converter woes. I plan to do a cylinder compression test while I'm in there.

I figured if I am going to take the plugs out to inspect them I might as well put fresh new ones back in. Its pretty incredible when you think of it, 120k miles on a single set of plugs.

I got the exact Denso plugs for $90 on eBay with free shipping. Seemed a fair price and they came to my mailbox 3 days later.

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Any special advice before I go swap all 8 plugs on my 2004 LS430? I just rolled over 105,000 miles. The originals have been their since its birth in summer of 2003.

A few questions:

1) Any special methods to remove the Coil Over Plug (COP)? I suspect the plastic COP assembly has gotten a bit more brittle since 2003. Also wondering if the rubber boot is stuck tight to the plug will the COP snap into pieces. I presume gentle twisting action is best but at $100+ per COP I don't want to damage any. If the bottom of the boot is accessible, I like to run a tool, such as a dental pick, around the lip of the boot to break the seal

2) What about spark plug socket. Wondering if I should sacrifice a 5/8" spark plug socket and extender and tack weld together so the extender doesn't come off the socket after I torque the new plug in.

Keep a long magnetic wand and flashlight handy for fishing if the need arises

3) Dielectric grease on new plug and boot upon reassembly or don't bother? Yes. Or in a pinch, use KY jelly :)

4) Anti-seize compound on new plug threads? Yes

And...how about taking some pics and making a "toot" for posterity?

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How did the old plugs look? Were any noticeably worn more than the others?

Actually for 106k miles they looked pretty good. Maybe slightly wider gap but not significantly so. Also all plugs looked the same so I don't think I have one bad cylinder (running rich and/or missing ignition).

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