Gen 2 PCV replacement how-to with photos

Thanks for the reply! Last questions, what are the possible drawbacks to a faulty PCV? Less mpg? Poor running engine? What happens when the valve completely fails?

 

You don't want a clogged PCV valve for the following reasons: 1. Causes oil burning, 2. Causes blown engine seals/piston rings 3. Significantly hurts performance, 4. Significantly hurts fuel economy.


Also I wanted to reply to the main topic of this thread which is the fact that people think you need to remove the wiper cowl in order to get to the PCV valve. This is not true. For about 9 months now, I was eagerly anticipating the replacement of the PCV valve in my friend's Toyota Prius as his car is burning a bit of oil and was hoping this would cure him of this issue. So today he had his car over and I basically forced him to let me work on the vehicle and tackle the job because he just doesn't have it in him to do the job. Anyway I had this and a few other threads related to the PCV valve up on my computer, briefly consulted them and basically said, "F*** it!" I'm going to see if I can do this faster.

So I did a lot of the same steps other people did such as moving the relay box out of the way (just removed two bolts, did not disconnect/pull on the plastic harness holder that attaches to the cowl, removed the intake air box, unbolted the main harness, disconnected the spark plug wires and fuel injector wires (which are connected to the main harness), unclipped the main harness, and a few other harnesses such as the orange one from various metal posts. I unclipped a small orange harness from metal post to get to main harness lower near the intake manifold at one point, though I'm not sure if this was even necessary.

Anyway so after the main harness was loose from the valve cover, I was able to pull up on this main harness and bend it up and outward, requires a little bit of playing with it but otherwise the whole L shaped part of the harness was able to come out and be bent a bit and there I had easy access to the PCV valve. I also removed one of the ignition coils near the PCV valve so I didn't risk damaging it with the 19MM wrench I used. The PCV valve is pretty tight in there, so remember lefty loosey righty tighty, put the box end of the wrench on the valve (after disconnecting the hose), got a block of wood, placed on edge of wrench and hammered the wood down until it the PCV valve broke free.

Job was so much easier than I anticipated and I really could have had the job done in about an hour had I not gotten distracted and decided that I wanted to clean up both ends of the electrical ground coming off the engine block (btw VERY good idea to do!!!), cleaned some dirt out of the air box and I also cleaned the MAF sensor very delicately.

My biggest disappointment about this job was the fact that the PCV valve WASN'T clogged which means that his oil burning is likely caused by simple wear or something to that effect. However because I cleaned the MAF and one engine ground, I think my friend should see a fuel economy boost.

Also I saw something interesting with the oil level today which confirms what a lot have said on here. So, several months ago my friend had the oil change done and the oil was at the top mark, and the car said he was averaging 40mpg. I told him he should only fill 3/4 of the way on these cars because it hurts MPG if you fill to the top. So here we are, like 8 months later and the oil is at the halfway mark so I go to check the car's average fuel economy and I see that it's averaging 46mpg, confirming the point about the oil level and the fuel economy. I'm hoping to find the right synthetic for this car so that he can fill the oil to the 3/4 mark and not have to worry about it running out of oil between oil changes.

 

I just did mine today, with 165k miles on the original. I removed the wipers and cowl, it was very easy! I would highly recommend this method, only took me 30 minutes to complete, nothing complicated at all. If you can use a ratchet, you can accomplish this job easily. I do recommend a 19mm deep well socket, as mine was pretty tight, so used a breaker bar to loosen. Thanks Galaxee for the great write up !


iPhone ?

 

This is an embarrassingly stupid question, but how do you remove the clips in step 1? I'm unfamiliar with those types of clips. Thank you.

 

You push down on the middle of them.

 

You press UP from underneath the small clip using your finger. The center rod will lift up easily and then you can remove the entire clip. It should all come out rather easily and you shouldn't have to force anything.

 

Well, I just replaced mine in my '02 at 142,000 miles. While it still rattled, you could tell if you blew through it that it no longer sealed correctly. My '02 had two Phillips screws in the upper corners of the plastic wiper cowl cover, but I've done this whole thing before, as documented at Replacing the Inverter Assembly on a 2002 1st Gen Prius « Russ' Do It Yourself Home Workshop, so it really wasn't a big deal. I actually disconnected the fuel line to get it out of the way and welded the bracket that was broken that holds the cable (not sure what cable) at the back of the engine near the firewall. So, my replacement took a while longer, but it's all done. Now, on to the 2005 with 120K miles...

 

Thanks for the responses! Well, I just did it, and it took about 1 hour. I could probably do it in 30 minutes the second time. Three questions:

1. Is the pcv valve supposed to show any threads when fully installed? I hand tightened the valve, then tightened it a half turn or so more, but a few threads still showed.

2. Is it a bad sign if the old valve had oil on it?

3. How can I tell if the old valve wasn't working?

Thank you!

 

As an update, the pcv valve swap made my check engine light temporarily disappear, but it's back today, so I'll try replacing the mass air flow sensor next.

 

As another update, I cleaned the mass air flow sensor with cleaner I bought from Toyota, and my check engine light has remained off since then. The code P0101 (mass air flow sensor code) was previously tripping the light. In addition, I've observed about a 3-4 mpg increase.

 

Fantastic, thanks! Toyota says there's oil in the intake manifold, and it's caused by the PCV valve being bad. They wanted to charge me for cleaning it out.

I have no check engine light on and mpg hasn't changed. 2005, Gen II Prius, 144,000 miles, bought new.

I would think that once the valve is replaced, the oil in intake manifold would eventually get sucked up(?) or eliminated as time and mileage go by.

So... do I need to get to and clean out the intake manifold while changing the valve? (Engine's never been touched except plugs at 100K, just oil and filters changed regularly (5K for oil/filter).

Thanks

 

so theres no way to reach it from the bottom with the car on ramps...damn

 

Had to remove wipers and everything and this plastic cover not mentioned or pictured. Was a pain. This is an 2006, does everyone have his cover over the hoses?

 

I just replaced mine the "easy way": No PCV valve on my '05? | PriusChat. No need to remove wipers, cowl, etc.

 

This is one great post! Set the laptop next to my Prius and followed the pictures step-by-step. Reminded me of a cook following a recipe. I went ahead and pulled the cap off that plastic L shaped box and pulled those thousand wires out of the way. Changing original plugs at the same time. BTW, we bought our Prius new 155,000 miles ago. Mobile-1 5/30 every 5K miles, but on original plugs and pvc valve. Also, changing transmission fluid for the first time. Anxious to see if there is any improvement. Great Car !!

 

Should anti-seize compound or something be added to the threads? The OEM Denso PCV valve doesn't have any tape on the threads like the above photo.

 

No need to remove all the wiper stuff. I cleaned the throttlebody and maf while I was there.

 

I just replaced the PCV on my UK spec 2007 at 135000 miles. I only had to remove the fuse box and one coil plug. I used a 19mm ring spanner (wrench) with a small set of mole grips as an extension to get a bit more torque to get the thing out. About 30 mins all told — not bad for first time. Thanks all for your posts on this. They gave me the confidence to do it.

 

Hopefully this will reduce my oil consumption between changes.

 

Mole grips are a UK trade name for the US trade name Vise Grips.