How to Replace Gen II Prius Spark Plugs and PCV Valve

This is why it is good to make the effort to locate and use a torque wrench, and strive for 13 ft.-lb. Then we don't have to have discussions about what "hand tight" means, which is certainly subject to lots of interpretation, not to mention my ability to hand tighten may vary considerably from yours.

 

They seemed pretty snug, though I'm just going to be borrowing a wrench from a bud just to make sure. Then I can go in and clean the throttle as well.

 

And I def researched and DID NOT use anti-seize .

 

I just finally got the time to do my plugs. Here's some advice for first-time plug changers (mostly based on my online research):

Patrick, I tried to use Crescent X6 CX6DBM2 and there was not room to get it around the PCV valve - the wrench walls are too thick around its opening. I tried a deep 19mm socket and there wasn't quite enough room to get a ratchet wrench on the end. So I had to use an adjustable crescent wrench which was painful going 1/8 turn at a time and flipping it but luckily it was removable by hand after a full turn or two.

To torque it to 20ftlb I used a 19mm crowsfoot (get one with hooks at its tips so it keeps contact on 6 sides) and a torque wrench. The torque wrench is only accurate when it's 90 degrees perpendicular to the crowsfoot.

I had to white glue the rubber insert into my spark plug socket wrench as it otherwise kept slipping out and remaining on the plug. I also had to use electrical tape to connect the socket to its driver as the driver's spring-loaded detent ball would not hold. If you have an extension with a locking detent ball that should also work.

From a motortrends article: Loosen spark plugs a small amount, then tighten, and repeat, loosening a little more each time till they turn easily. If you just force it to loosen you'll hear lots of creaking and it will turn in little jitters. I think all that is forcing accumulated carbon gunk near the end of the plug through the threads which can damage them.

A lot of sites say to clean the spark plug holes to avoid problems with carbon gunk jamming the threads and screwing up torque values. I used a small jewelry cleaning brush with electrical tape extension and mineral spirits. I also used a long handled paint brush to swipe black from around the top of the hole where the spark plug washer makes contact, adding mineral spirits for a couple spots that wouldn't come clean with a dry brush.

Since you're highly unlikely to change Prius plugs more than twice in the life of the car, all my extra effort may be overkill, but it adds peace of mind.

As many sites say, don't use anti-seize on the plugs as it affects the electrical contact and torque values and the plugs from most manufacturers (ie Denso who makes the OEMs) have a coating already. I've also read anti-seize should not be used on the PCV valve for the same reason that it affects torque values and also it screws into an oily area and ends up getting oil in its threads anyway.

Some suggest using silicone lube on the end of the valve the hose slides onto, while others warn that can make the hose slide off in a pressurized system. Since there is negative pressure to suck the hose onto the valve, lube strikes me as safe here.

 

OP - Thanks for the guide. I replaced my plugs and PCV Valve today and all went well. I took some photos and want to share.

The two photo below shows how I routed the wire harness. This part took me the longest to figure out. I ended up wiggling it free and was able to prop it up against the cowl. This gave me enough room to use a regular 12 point wrench to remove the PCV valve. I didn't need to use a ratcheting wrench



The photo here shows my old plug. The zoomed in one is of interest. It shows that my old plug was rounded off toward the edge. The center is not worn down and gap measurement is the same as the new plug. The age is 112k miles. I wonder if I could of gone to 200k miles with the old plugs.


Bonus... I din't expect to see the throttle body when I read through the guide. Since it was there within easy access, I cleaned it with a rag and alcohol. If I knew, I would of prepared a bottle of throttle body cleaner. I also cleaned the mass air flow sensor. (forgot to take picture of that)


While at it, I also drained and filled the coolant in the radiator.

 

Thanks for the pictures! I just wanted to mention for the benefit of future readers that I've read in many places you should never run a gap tool through the gap on an iridium plug. The gap is set at the factory and iridium is very brittle and easy to break or chip. It can't be bent to change the gap.

 

Look at those plugs. Once again, virtually no wear. That iridium is good stuff.

 

You can run a gap tool through an iridium spark plug. Only the center electrode and the small pad on the ground electrode are iridium.

But, they are set at the factory and shouldn't need adjustment.

 

I've used anti-seize on the threads of all plugs I've installed, copper, platinum, and iridium. Never had an issue with any of them, and the plugs come out easy next time I need to remove them. I have a can of lead based anti-seize, and it works great every time. I looked up some info on this topic, and here is what I've found. Anything but conclusive...

How to Replace Plugs With No Anti-Seize | eHow

http://www.ngksparkplugs.com/pdf/TB-0630111antisieze.pdf

Spark plugs anti seize GOOD or BAD?

Although the NGK case does make some sense, but the risk of seriously overtightening seems small if you are using the proper tools (torque wrench, etc).

 

IMO, there's so much misinformation and fear mongering out there its pitiful. I think a lot of it stems from people doing something wrong and not willing to admit it. To save face, they make up a story about something and it becomes a fact. I personally see no reason to avoid putting anti seize on plugs of any type but, NGK does clearly say not to use it on their plugs. Idk why.

 

From NGK

Applying anti-seize to the threads of spark plugs that have a metal plating allows the installer to mistakenly over-tighten the spark plug in the cylinder head; This stretches and fatigues the threads of the spark plugs, causing a much higher probability that the plug will break during installation or in some cases upon removal.

All NGK Spark Plugs are manufactured with a special trivalent Zinc-chromate shell plating that is designed to prevent both corrosion and seizure to the cylinder head; Thus eliminating the need for any thread compounds or lubricants.

 

I used NGK plugs, and anti-seize on my plugs. Have 60K miles on them so far. We will see in 40K miles whether I have any problem with them, I'll report back then!

 

chances are, there will be absolutely no problems with using anti-seize. Just they don't recommend it based on their reason it might over tighten your plugs.

 

1. I would avoid the use of lead-based anti seize compound as that may contaminate the catalytic converter, to the extent that some of that gets burnt in the combustion chambers.

2. I agree that NGK does not recommend use of anti seize compound on their spark plugs.

3. The ground electrode on the Toyota spec'd iridium plugs has a platinum tip attached, not iridium. The center electrode has an iridium tip.

4. There is nothing wrong with checking the gap on a new iridium spark plug and adjusting as needed. However a used spark plug should not have the gap adjusted as the ground electrode may be brittle and break off when reinstalled in the engine.

 

I noticed my ICE is revving louder (faster rpm?) on city roads (stop and go condition). Is this normal because of the new plugs and PCV valve or from cleaning the throttle body?

 

Patrick, excellent point on the lead based anti- seize, it is a strong catalyst poison. However, so are nickel, iron, copper, and any other metal that may contaminate it via the same route, but this may be the best argument yet to not use anti-seize if you can avoid it. And in reality, I took out plugs that had 110k miles on them, and they came out fine with no lubricant, and they were NGK. Something for me to consider next time.


iPhone ?

 

I would not think this is normal.

 

My Prius is fine now. I research and found that the high revving symptom is related to cleaning the throttle body. The solution is to let the car's ECU relearn the idle. It just took time to do so.