4runner20

What I thought might be an easy job has quickly turned into a nightmare! Where is the pcv valve located on my 1990 4runner 3vze 5 speed 4x4?

scope103

It's a secret.

Well, I guess I can tell YOU. It's on the top of the passenger-side valve cover gasket. Some people claim they can reach it with some specialty long-nose pliers (I sure can't).

But what's going to hang you up is the grommet into which it is held. Unless you've replaced that grommet in the last 40,000 miles, it is the consistency of concrete. On mine, I had to destroy the grommet to get the PCV valve out, and that was with the valve cover gasket sitting on the floor. I would never have been able to do it with the plenum still in place. And even with the plenum off, destroying the grommet means dropping little pieces inside the valve cover. You don't want to do that with the valve cover in place.

So while replacing the PCV valve is probably part of a good maintenance procedure, I advise waiting until you, oh, check the valve clearance. Then you'll have to remove the plenum and valve covers, and it won't be impossible to do.

Gamefreakgc

Welcome to the nightmare that is the PCV valve on a 3VZ-E! How can a $5 part be so hard to replace?

I second what scope said. It's too much trouble to do on its own. Just leave it alone until you need a valve adjustment (a bigger pain) or a timing belt change (even bigger pain).

In order to get at it without dropping any plastic parts in your engine and possibly ruining it, you'll need to remove the air chamber, fuel rails, engine hangers, EGR, injectors, engine wire harness, and the valve covers. All this for a $5 part and a $2 grommet. Not to mention in order to do this, you'll need about $70 in gaskets to seal it back up correctly.

If you do ever need to do a valve adjustment, PM me. I did mine about two months ago and my truck feels like new again. I have some tricks that will save some time too.

Hilux4Life

Sorry for the stupid question but how do you know if it needs to be replaced? Is it something we should just replace ever few years? Just curious

4runner20

I hasnt been replaced ever. It's 23 years old.

jason191918

I was able to get at it with some goofy tools. It was a PITA. I think it would be easier to pull the upper intake.

scope103

What sayeth the Good Book?
http://personal.utulsa.edu/~nathan-b.../1maintena.pdf

PCV is not a scheduled maintenance item. Replacement is not even in the section on maintenance operations. The only reason to replace it is because you already have the right valve cover off, and the replacements are so cheap.

Chooch

The PCV valve isnt that hard to do if you have the right set of pliers.

Found a set identical to this at my tool store on clearance for 8 bucks or something, let me tell you best 8 bucks ive ever spent. I got the ones with the 45 degree head.


I bought them specifically to do the PCV valve and ive found myself using them almost everyday (im a Automotive Mechanic)

It does take a bit of time and screwing around under there to get it out but its possible, took me about 15mins to replace the valve. If you really want to replace the valve I highly recommend getting yourself a set of those pliers. You'll thank yourself when you go to use them again and again.

And yes I replaced the grommet to, these pliers are awesome!

Gamefreakgc

In my experience though, it can be incredibly difficult to get out. If the grommet was like mine, I had my knees on the valve cover, a pair of a vicegrips on the valve and pulling it and it would not come out, not without the risk of breaking my valve cover. I had to chip away the old grommet with a hammer and a wedge for 15 min to get it out.

Notraps

I'm considering doing this becuase I feel like it's the most likely part causing my issue.

That issue being: When I take my oil cap off...the idle is normal. When I put my oil cap back on...the idle is at 1250rmp.

Thoughts?

I just bought a truck that is in need of some love and I'm thinking it was more love than I expected. :|

ksti

READ THIS


[IMG]Quote: Originally Posted by brentcole5------- negative pressure because after i took the cap off and noticed the idle drop i just set the cap back on and the idle picked up again


Thanks to MudHippy
That's correct operation, and confirms your PCV(Positive Crankcase Ventilation)valve IS functioning. You'd notice the same thing if you removed the PCV valve hose with the engine running too. Here's why. Your PCV valve is a one-way valve in a rubber hose connected to the valve cover at one end and your air intake at the other.

O.k., so when your engine is running the intake is sucking on that hose through the PCV valve as it sucks air into your engine. Some air from the intake is also blown simultaneoulsy into the crankcase through another hose creating a positive pressure flow, out of the crankcase, of blow-by gasses through the PCV valve into the intake. Whatever blow-by gasses sucked, through the PCV valve, out of the crankcase get recycled back into the combustion process through the intake.

This system causes a vacuum(negative pressure)under the valve cover due to the constrictions in the flow of the blow-by gasses from the crankcase to the PCV valve. When you remove the oil cap(while the engine is running)and break the valve cover's air-tight seal it prohibits that from occuring. This creates a vacuum leak. Vacuum leaks cause your idle to lower and usually make the engine struggle to run at all.[/IMG]