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Replacing spark plugs in '07 Lexus GS 350

I this a DIY job or better left to the professionals.

I was going to look at a picture to get an idea, but this is what I found:

So step one is remove that cover and see how hard it is to get to the plugs. If you aren’t comfortable doing this, then time to go to a good independent shop and have them do it. No need for a dealer, any good shop can do this. But do use the plug model that the manual specifies, no benefit to ‘upgrading’ plugs.

I’ve replaced spark plugs in my 4 cylinder Camry, so I’ve tested the waters of my automotive skills.
It’s just that the dealership gave my wife the 'ol “it’ll cost you 3K if you get the threads crossed”. I believe I have the appropriate tools. Just wandering if anyone has any pearls of wisdom in case a run into a fork in the road.

thanx Tex

On the surface changing plugs is simple but if done improperly it can open up a real can of worms. If you use a slow, methodical approach you should be fine. Here’s a few tips.

Remove the old plugs slowly. If one feels very tight then try snugging it up a bit tighter before trying to loosen it again. In other words, seesaw it a bit if have to do so.

When removing a coil do not pull it straight off. Try to wiggle it back and forth as you pull.

Check the gap on the new plugs and CAREFULLY adjust if needed. Do not ASSUME the gaps are correct as they are often not.

Use anti-seize on the threads of the new spark plugs.

Use dialectric grease on the inside of the coil boots before reinstalling the coils onto the plugs.

When installing the new plugs do NOT use a socket and extension. Use a short length of fairly stiff vacuum line that has an inside diameter small enough to create a tight fit on the end of the spark plugs and start them into the threads by that method. This assures that you will not strip or cross-thread anything.

Snug the plugs up by hand. Most long time mechanics tighten plugs by feel as that is far safer than a Ft. Lbs torque wrench or following shaky specs given in a manual. All that is required of the plugs is to run them down all the way and then give them a fraction of a turn.

Ignore the comment by the dealer about 3 grand if you cross them up. This sounds like yet again a shop that apparently does not have any clue what a thread insert or Heli-Coil is.
No doubt a service writer is the person who stated this to you. NEVER listen to these guys; and in some isolated cases these gals.
(Inserts and HCs are used to repair stripped threads and unfortunately, it seems like far too many mechanics and shops now seem to think the proper fix is to replace cylinder heads or complete engines after you float a homne equity loan to pay for it.)

That’s the proper method. An improper method would be the young tech at the dealership who will rip those babies out quickly with an air ratchet and ram the new ones home by the same method after cranking the air pressure on the ratchet up to MAX. Hope that helps anyway.

Since its a RWD based platform, then its actually going to be easier than a V-6 Camry, but slightly more involved than a 4 Cylinder Camry.

Off comes the cover.
Unplug the coil sticks from their wiring connectors.
Unscrew the bolt that holds the coil stick to the valve cover.
Twist coil stick side to side to break it free from the sides of the spark plug.
Pull up on the coil stick to unplug it from the spark plug.
Use proper spark plug socket to remove spark plug from cylinder head.

Reverse is the way to install.
I recommend using a torque wrench since you have only ever replaced 1 set of spark plugs before in your life. A seasoned mechanic will be able to feel the sealing washer crush, and know when to stop, but we aren’t going to risk that with you.


A few tips: the plug for each coil is retained by a plastic clip that has a press thing on the saide to press and remove them. These clips have a backward-sawtooth and should be pushed fully in before pressing the clip and pulling out or it’ll break off. If it does break, it isn;t a big deal, as the plug has enough friction to hold itself, but it’s better not to break them.

Unlike OK4450, I use a sparkplug socket and extension, without antiseize, but I very delicately “start the threads”. If it doesn’t start smoothly and cleanly with only my fingertips I back off and try again. The spark plug should not take any significant effort to screw in. I then use a beam-type torque wrench. The torque spec is on the plug box and/or on the NGK website. Use NGKs or Nippon-Denso. Do not use a non-OEM plug. Especially avoid Champions.

I have only the utmost respect for OK4450’s expertise, and all of his other commenst are spot-on. We just do this particular chore a bit differently.

I wish they made noise abating shrouds to fit in MY engine compartment. It’d be a nice accessory, worth a reasonable fee.

Good idea perhaps for an aftermarket accessories product…

Actually, I have no problem at all with using an extension and socket to install plugs. It sounded like there was a bit of trepidation in the OP’s question and I was just trying to head off a possible problem without knowing if the OP is a bit hamfisted or not.
My gut feeling is that he’s not.

The spark plugs on the left bank are under the intake manifold plenum. To remove the intake maniflod plenum you will need a long 5mm allen wrench (about 5 inches) and a metric socket set.
If you have not had the valve spring recall done yet (SSC ALE) you could ask your dealer to replace the spark plugs during the recall. All of the spark plugs must be removed to perform the recall.

They’re just different approaches. The idea of a plastic tube is a good one. It does for those without a delicate touch what I do with my fingertips, it enforces care in getting the thread started.

I did want to get in the point about the COP connector clips, though. I’ve broken a few of those buggers. They break easy.