BradTank

I decided to finally go ahead and do my spark plugs. I noticed there wasn't a thread with a step by step with pics, so I thought I'd add one. I got a quote from a dealer one time for this job, and it was just under $500, which is insane and probably takes a Lexus tech less than an hour to do.

It's a straightforward job, more difficult than an oil change or brakes, but MUCH easier to change plugs than most modern cars.

I highly recommend getting a set of spark plug sockets, the kind with a rubber retainer inside. You also need a set of socket extensions and flex joints. The most difficult part of the job is the angle going in and out can be tough, the right length of extension makes all the difference. Also, the consensus seems to be you should always do this job when the engine has cooled down so you don't pull the threads out.


The spark plug I used was Denso Iridium SK20R11. It is the factory plug and what I would recommend. You can buy them for around $10 a piece at Amazon or RockAuto.





First thing is to remove the engine cover, it's held on with two 10mm bolts.



Next you'll see you have a fairly clear path to get to them.

Drivers Side



The Passenger Side has a few things in the way, this black box tied to the air intake and the car battery. I was able to install only taking out the black box with the intake hose.



Remove the black box, it's held down by a 10mm bolt, 2 vacuum hoses, and an air intake hose.
Now you also have a clear shot at the passenger side.



Next, remove the coil packs, each one is held down by a 10mm bolt. I prefer to do it one by one so there's no mix up. You can either unplug them by the clips, or pull them out with the wires still connected. Just be careful to make sure you have enough slack when you pull it out of the way.



This is was the tubes look like when you pull them out



Next, take a 5/8" (or 16mm) spark plug socket, and with an extension, place it down the hole and turn counterclockwise. There should be very little resistance, just make sure its seated down completely as it takes some downward pressure.



After removing, inspect the spark plugs. Mine were actually in decent shape, EXCEPT for the one that was the most difficult to get to, on the passenger side closest to the firewall. My guess is the dealership that did the job skipped it, thinking no one would ever inspect his work.

A great way to put the spark plugs in so they won't get cross threaded is to get some 5/8" heater hose at an auto parts store, and place the plug inside. The hose fits the tube perfectly, and keeps it centered. Put the spark plug down the hole and press down firmly, then just keep hand tightening clockwise until the spark plug seats. This is a great way to make sure you don't get it cross threaded. Once it's seated and you can no longer turn the hose, I then remove and put a spark plug socket on, and turned it an additional quarter turn. The factory manual rates it at 15 ft lbs. It's very little torque.



I then took a little dialectric grease, and placed a small amount on the tip rubber boot that has the coil pack that adjoins to the spark plug.



I then seat the coil pack onto the spark plug, press down, and put the 10mm bolt back in. Be VERY careful about putting the coil pack bolt in. It's very easy to get it cross threaded and your screwing it into aluminum. Make sure the angle is correct, I would hand tighten and then just torque until it's snug.



The only plug that is a bit difficult to get to is the one on the passenger side, near the firewall. Even still, I was able to remove it without taking the battery out. Again, I found this one had looked like it had never been changed, so it had almost 150k miles on it.

After finishing, check your work and make sure all the coils are attached, with the weather clips snapped in and the coil packs screwed in. Make sure the packs are flush against the block. Then put the "black box" back in, attach the intake and vacuum hoses, then attach the engine cover.

My guess is the first time you do this job, count on it taking about 2-3 hours. After doing it once, most people could easily do it it in around an hour. I would go very slow and take your time, you don't want to cross thread the spark plugs into the block or the coil packs.

Lavrishevo

iTrader: (1)

Nice. Thanks for the pics and writeup. I used the same plugs but decided not to do it myself.

https://www.clublexus.com/forums/ls4...-tomorrow.html

lorenr

iTrader: (1)

Very nice write up with good photos. As you say, it is not a difficult job and your sure that ALL of the spark plugs are replaced. If the dealer only replaces seven plugs he gets a free set of plugs after eight jobs. That is an extra $100.00.

I really like the 5/8 heater hose. I've always used vacuum line hose, but the 5/8 hose looks better.

The spark plugs and cylinder heads may be dissimilar metals, but if a speck of anything gets in there it can bind the threads. Very bad. I will sometimes spray WD-40 down the threads on the head to clean them, but I always paint the beginning of the spark plug threads with Never seize (anti-seize). That way you can remove them next time.

One other thought and I don't know if it is true. A mechanic told me that even though Iridium plugs are good for more than 100,000 miles, to replace them at 60 to 70,000 simply because they are easier to remove. Since these plugs are cheap for us do-it-yourselfers, not a bad idea.

BradTank

Thanks.

The debate about using anti-seize or not can get heated, Denso's recommendation is to use nothing on these Iridiums because they're coated with a metal that's supposed to not seize. I ALWAYS used anti-seize on spark plug threads previously.

I read that some dealers like GM recommend just a drop or two of synthetic oil on the threads of modern plugs that don't require it, which is what I ended up doing. I just can't seem to get comfortable with the idea of using absolutely nothing on spark plugs sitting in an aluminum head that will likely be there for another 100k miles.

I've heard sometimes "old school" anti seize can affect how a plug grounds itself, and the spark plug manufacturers worry people will over tighten when it's coated with anti-seize. My guess is either method will work fine.

And the fact that the dealership skipped that last plug does tick me off, it seems you almost have to do jobs yourself if you want to see them done right.

1WILLY1

iTrader: (9)

best thread in a long time ,,thanks

LiCelsior

iTrader: (32)

awesome write up Brad! this has to be included in the DIY thread. this gives me more motivation to clean the engine once the cover is off, thats filthy lol.

BradTank

I'm glad my filthy engine inspired somebody.

I did some clean up with some compressed air and a wet rag when I was buttoning everything up.

Lavrishevo

iTrader: (1)

Yeah, anti-seize is a bad idea. If you use anti-seize and a torque wrench to torque the plugs properly then you will over-torque the plugs. Lexus does not use anti-seize lubricant when they replace the plugs.

https://www.clublexus.com/forums/8361224-post30.html

KawiLex

My plugs were done at 125K.. unfortunately.. I only got to inspect them and that was it!!

lorenr

iTrader: (1)

I used to be one of these guys, but I ran out of money and decided I wanted to retire. I do own an IS F though.

However, they are a pretty talented group of gear heads. The answers will help with coating of spark plugs.

http://board.moparts.org/ubbthreads/...=0#Post8051719

Lavrishevo

iTrader: (1)

Why look at opinions when both Lexus and the manufacturers of the plugs say not to use it?

BradTank

I think the issue is sometimes manufacturers have different priorities when they recommend something that's more in their best interest and not necessarily looking at the big picture.

A good example would be something like "lifetime" transmission fluid that Lexus says you never need to change. That might look good to a new car buyer, but what about the person that has 150,000 miles on their car? Doesn't that effect the longevity? Lexus cares more about the guy buying a new Lexus than one that's 10+ years old.

Denso is concerned people might overtighten their plugs, break them, and then complain and demand a refund when they have issues right out of the box. Or that the person slathers on too much anti-seize and it gets on the electrode, causing a misfire. That could be the main reason they don't want anti-seize on their plugs. They're not as concerned about the person 10 years later pulling their plugs out and stripping the threads.

As car owners (and not spark plug manufacturers) we're more concerned with having seized spark plugs in an aluminum head down the road. If you have to pull a head and take it to a machine shop, you're talking big money.

So I can see why people question authority on this. I feel like it's probably best to follow Denso, but I sort of split the difference by putting just a drop or two of synthetic oil on it, something GM recommends for their Iridium plugs. I then hand tightened it, and put one quarter turn further than that with a wrench per Lexus recommendation, so that shouldn't be a problem with respect to over tightening.

fensterlip

Embedded in the moparts link is a link to NGK which gives good details about this.
http://www.ngksparkplugs.com/pdf/tb-...1antisieze.pdf
Looks like if you have dark metal colored plugs they don't have the high tech anti-seize plating and it will make sense to use a very small amount. The silver colored threads have an anti-seize plated onto the plugs.
It seems like their main complaint is that it's too easy to over-tighten the plugs - again use your torque wrench and being careful seems to be the order of the day.
I would think that if you use a very small amount and watch the torque specs you should be OK.
I have some of the copper stuff too that I use on the back of rotors to avoid seizing to the hub and I suspect this could avoid any heat transfer issues also. They feel too much anti-seize could cause plugs to run out of heat range. Again a very small amount would be the solution - or copper anti-seize.

Legender

The heater tube is a good idea... I use an old spark plug tube from prior jobs... they fit perfectly, have great rigidity and don't cost anything. Excellent write up and thanks for sharing.. I've done 2 430s and 2 400s.. easy and straight forward job. Thank you for taking the time to document and post. Very helpful for those who didn't think they could do it.

I learned to do plugs with my dad on our old Chevy wagon with a 350... always hated that blind insertion.

I don't have the rubber retainers in my old socket set, so when I get the plug loose enough, I swap to the old rubber tube and use that to finish the job. Guess I really could get a new spark plug socket... lol

SQuester

Nice work Brad! Always wondered why there wasn't an DIY thread on this, you delivered perfectly.