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Discussion Starter · #1 · (Edited)
This is an easy job that doesn't take long to do, nor cost too much, but yields good results that you notice right away! It will take you longer to read this DIY than to do the job, ha ha! I wanted to write a DIY that will allow someone who's never done this before and who's not mechanically inclined to do this job, and maybe to gain some confidence about doing other DIY things with cars.

(The pictures from from a '00: the '98 - '00 Ravs don't have a distributor, so '97 and older won't look like these pictures, and the parts are different, but the plug change process should be the same).

DIAGNOSTICS:
You might need new spark plugs if you haven't replaced them recently. Our Ravs come with dual electrode platinum center plugs which have a very long design life, but that also just simply wear over time nonetheless. I've read that some people get 100K or more miles out of them--even read that someone ran the factory plugs for over 200K! But considering that a set of 4 new plugs will only cost you about $25, its not something that's going to break the bank to change. I believe the Toyota service interval is 60K for Denso plugs, but I'm not positive on that.
You might need new ignition wires if you've never replaced them. The wires build up resistance over time. The max resistance by Toyota specs is 25K Ohms, meaning they should be replaced if they reach this level of resistance. In my opinion, its as much work to pull the wires to check the resistance as it is to just replace them, and considering that the NGK wires are less than $20 at Advance Auto with a coupon code, you might as well just replace them and forget about it!

SUPPLIES:
- 4 new spark plugs (Toyota Service Manual calls out Denso/Nippon Denso PK20TR11, or NGK brand BKR6EKPB11 plugs specifically; these are dual electrode, platinum center, gasket-type spark plugs which are pre-gapped to 0.044 in; many people in this forum have had bad luck with Bosch plugs)
- new ignition wire set (OEM part #90919-22400 for '98+; a much cheaper but quality aftermarket alternative are NGK wires #8916, which are what you'll see here)
- special spark plug socket, 5/8" size (can be got for $2.49 from Harbor Freight)
- 6" extension for ratchet wrench
- ratchet wrench
- torque wrench (not absolutely necessary, but very good to have)
- dielectric grease ($1 for a small pack, you'll have plenty left over)
- anti-seize (optional, in my opinion, read through the steps, or $1 for a small pack, you'll have plenty left over)
- pliers (optional)

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(PRICE: I was able to get the spark plugs and ignition wires for just under $50 together from my local Advance Auto store, using an online coupon for 40% off and picking up in the store.)


STEPS before starting:
If you use the Toyota suggested plugs listed above, your plugs should be gapped from the factory to 0.044, so you should be able to drop them right in without adjusting anything. If you choose to measure the gap, use a wire-type gauge (There's a note at the end of this DIY which prefaces my personal opinion on this). If you use iridium plated plugs, do not measure or gap them, because you may accidentally remove the plating: just pick a quality brand that offers the plugs in 0.043 or 0.044.


STEPS:

1.) The engine must be cold. Disconnect the battery by disconnecting the negative (black) terminal. This is just an extra safety step to prevent someone from, say, attempting to turn on the car in the middle of your project while you're looking for something that rolled down the driveway, etc.


2.) Under the hood, locate the ignition wires. The OEM wires are black, and run transversely across the block; there are 4. You'll see that they each individually end on one side as a rubber boot, and on the other as a plastic clip. Clean the area near the boots, because you'll be removing these, and you don't want anything to fall inside the cylinder, which you'll see when you pull the boot out.


3.) Locate the "separator racks", which are little plastic devices that hold the wires and keep them apart. Loosen the wire that leads from the first boot (left most) from the separator racks so it is free to move. Be careful with the first and third wire separators, as they are secured to the block and are easily broken. (Note: its doesn't matter which plug you start with, but I just did it left-to-right).




4.) Disconnect the wire from the socket into which it is plugged on the driver's side end. You can follow the wire from the boot end, and you'll see that its plugged into the socket which is closest to you as you're leaning over the radiator. (If you plan on just doing the plugs and are NOT replacing wires, you don't need to do this--leave it connected and skip to the next step.) The clip has a notch on the bottom side which must be pressed with a small flathead screwdriver to release it, its a tight space--a coin might work? Or, if you know you're just going to throw away the wires, you can use a pliers to clamp and lightly press the plastic rails on the top, but understand that this will break them and render them useless. It was rather cold in the garage, so I just opted for the pliers method! ;)







5.) Follow the now-disconnected line back over to its boot side. The boot is removed by hand only: you just have to work it side-to-side a bit, then twist and pull up at the same time. Look at the boot of the new wire to see how it is secured. Remove the boot end; make sure that nothing falls inside the opening.


6.) Look down inside this cylinder and you'll see the top of the spark plug. Affix your special spark plug socket tool to the 6" extension, and place it inside here. You'll hear/feel a plunger-like effect when you have it properly seated on the plug, because the inside of that special socket has a rubber liner with a hole at the top.




7.) Attach the ratchet, and turn counter-clockwise to loosen the plug. The plug (hopefully) isn't torqued down too much, so it shouldn't take a tremendous effort to turn it. Do not use any impact techniques to loosen it (meaning, don't hit the wrench with a hammer or anything like that). If the spark plug seems extremely tight, then the last person must have over-torqued it, so abandon the project and call your mechanic friend, because you don't want to break the plug in the process of trying to remove it. Once its loosened some, remove the ratchet, and turn the extension by hand. There's a good 1.25" of threads on the plug, so you'll be turning for a while.




8.) Once clearing the threads, you can remove the extension, and you will see this.




9.) Pluck the old plug out of the special socket by hand. Take your new plug and put a THIN layer of dielectric grease on the surfaces of the porcelain end (the tip and porcelain), and a VERY VERY VERY THIN layer of anti-seize on the threads. It should be so thin that you can't see it, but its there (put a very tiny bit on your fingers, rub them together, then rub the threads; if there's any filling a thread, remove it with your fingernail and a towel). Anti-seize is optional: its better in my opinion to use NO anti-seize than to use too much, so when I say THIN, I mean THIN. Anti-seize is a lubricant, so the issue becomes over-torquing if you use too much. Its used in this application to prevent corrosion that later makes the plugs hard to remove. If you use too much, you run into issues with both over-torquing and heat dissipation, and if you use really a lot, you'll end up with anti-seize in the block. If you are uncertain about your ability to gauge what's "thin", and you're using NGK or Denso plugs, I'd say just don't put any on. NGK claims that their plugs are coated and don't need it, and factory Denso plugs I've seen look to me like they don't have it. If you do put anti-seize on the threads, be sure its on the threads only, and not within perhaps about 1/8" of the end. Just do not get carried away, because more is NOT better.







10.) Insert the new plug into the special socket (electrodes facing out).








11.) Using just the extension, insert the new plug, and turn it by hand. Turn in reverse every now and then to be sure that you're not cross-threading the plug as you screw it back in. Continue turning by hand-only until its very snug and you can't easily turn it anymore.




12.) If you have a torque wrench, set it for 10 ft-lbs if you used anti-seize, or 13 ft-lbs if you did NOT use anti-seize. Remember, anti-seize is a lubricant, so you must reduce the torque spec if you use it. Also, consider the tolerance of your torque wrench: if you have wrend that +/- 1 ft-lbs in this range, then consider that. Attach the torque wrench, and slowly torque to spec. If you don't have a torque wrench, I've read you can tighten the plug by hand till you can't tighten it anymore )"finger-tight"), and then just attach a wrench and turn it 3/8 to 1/2 of a turn; I haven't done this myself because I use a torque wrench, so if anyone has, please confirm this!




13.) Remove the extension and the special socket. Look at your new wires, and you'll see that they are numbered from 1 to 4. Look at the wire that you just removed: there will be a very small number on it. Match this number to the new wire, and compare their lengths to be sure (they should be the same number and same length). This is why you want to do this one plug-wire set at a time, so you don't accidentally connect the wires from say cylinder spot #1 to wire connector spot #2.




14.) Holding the wire by the boot end, insert the boot end connection over the spark plug, in the same orientation as the old wire. Press firmly and slightly turn the boot to secure it. It should be secure and flush; compare it to the other wires which you haven't removed yet.




15.) Plug the opposite end of the wire into the socket, noting the orientation of the other wires for guidance. You'll hear a "click" sound when its secured in place.




16.) Repeat the process for the other 3 plugs and wires. When complete, secure the new wires into the separators.




Clear the bay of tools, reconnect the battery, and start the engine. Enjoy the new zippiness of the ride!


About gapping the plugs:
I'm not an expert on anything, and certainly not spark plugs. But I have noticed that there are many opinions about gapping "pre-gapped" plugs, and even about measuring the gap on pre-gapped plugs. I picked Denso PK20TR11 plugs, because that's what was in there before, and they lastly a very long time. These plugs are pre-gapped at 0.044 in; the Toyota spec is 0.043 in (difference of 1 mil, or 1 one-thousandth-of-an-inch). I've done some machining before, and 1 mil is certainly measurable. I was taught that your measuring device must be more accurate than your spec by at least an order of magnitude; so, you're pushing out to 1/10,000th-in tooling for a gap gauge. Also, Toyota doesn't state a tolerance range, and limits the spec to 2 significant digits on the metric conversion as well (1.1 mm), so the intended level of precision is unknown. This makes me think that sweatin' it over a mil isn't necessary, but that is my opinion. Also, because these are dual electrode plugs, the gap is not a matter of linear clearance between two planes, but rather is distance between two (presumably) concentric curved cylinders of different radii. For this reason, I think a wire-type gauge should be used for measuring these plugs, if you chose to do so; coin guages and blade feeler gauges will not be able to produce accurate readings on a dual electrode plug. In my personal opinion, +/- 1 mil is not something I'm going to worry about in this application, so I didn't adjust the gap on my Denso's. That's my personal opinion, do as you'd like. My plugs were good right-outta-the-box, so it was as simple as dropping them in, and they feel great!
 

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I broke my separator that is intact on the cylinder head and the other one that is hanging. The OEM I bought had one separator but aren't horizontally strait, and it made the my high tension alignment a bit ugly to look at. :\

Btw, what happens if there are no Anti-seize put on the sparks?
 

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Discussion Starter · #7 ·
I broke my separator that is intact on the cylinder head and the other one that is hanging. The OEM I bought had one separator but aren't horizontally strait, and it made the my high tension alignment a bit ugly to look at. :\

Btw, what happens if there are no Anti-seize put on the sparks?
Yeah, those separators are SO easy to break! There are some aftermarket separators that are more pliable.
As for what happens if there's no anti-sieze: some people use anti-seize to prevent corrosion/expansion threadlock, just meaning that anti-seize tends to make plugs easier to remove later (it prevents the "seize" that makes it hard to turn the plugs). However, I've read that NGK & Denso plugs have a special thread treatment that effectively serves as anti-sieze. So its really a personal call, in my opinion: however, what's VERY important to remember, always, is that anti-seize (whenever you use it) is a lubricant, so it will allow the threads to spin with less resistance. For this reason, you need to REDUCE the torque spec when using it, usually 15-20%. The last thing you want to do is over-torque a spark plug, and break it off in the cylinder!! And the torque spec on plugs is so low in the first place, that I'd just say use extra caution when tightening down a plug any time, and extra extra caution on one that has anti-sieze on the threads.
 

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I'm not an expert on anything either, but I can say that during my teens I assisted my older brother (a qualified motor mechanic) with his very many projects on cars, from regular repairs for a local back yard car seller to work he did for locals and his own cars as well the family cars. We would have worked on many dozens of cars in those days. So I learned a helluva lot, probably about all there is to learn, and since then I have fully restored one car, refurbished two others, and spent lord knows how many hours fixing just about everything there is to fix on a car. The only thing I've never pulled down is an automatic transmission. That was some 50 years ago, and though I'm not a qualified mechanic myself, I would say I'm pretty close to it and I have always fixed my own cars ever since to this day. As for the torque spec for spark plugs, I've never torqued them down in my life. The general rule is to tighten them by hand until they turn no more and then give just one quarter turn with the wrench. In fact that's even illustrated on a pack of Bosch plugs that I have on hand, and I would NEVER give them up to half a turn. As for anti-sieze compound (generally copper based grease) I don't follow your logic. The grease may assist the plug to thread in smoothly (and prevent seizing in future) but that's the extent of it. Derating the torque setting makes no sense at all to me. Once the plug is seated on the head by hand then the torque spec is to ensure that the sealing washer will be correctly sealed and that has nothing to do with anti-sieze lubricant. Think about it - once the plug is seated then it's seated and you just tighten it down. An extra quarter turn or a torque wrench makes no difference because what you are doing is torquing the sealing washer down on the head and anti-sieze compound is totally irrelevant. And getting anxious about how much to use is also irrelevant. A photo in my workshop manual actually shows quite a thick coating on the threads, and I don't think it is important to worry about whether it's a visible coating or a very thin smear. However it does need to be enough to achieve its purpose. Incidentally, if spark plugs do seem to be seized or hard to "crack" then run the motor for about a minute or so - just enough to warm the head and plugs. Just as you heat a seized bolt with a gas torch to release it, you can also get a seized plug out this way. I'm not critisizing or challenging your post or methods, but I simply can't agree on your torque spec logic based on whether or not anti-sieze grease is used.
 
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