PCV Valve Replacement with Pictures

Den, would a deep 22 mm socket, or an uncut wrench not work then? It "looks" like a socket wrench could be dropped onto it. Yeah, I know...

 

I don't think bisco was making any smart remarks, he was just asking questions and want to know the reason. I would be asking questions too if I don't understand why someone would replace something, such as transmission drain and refill since everyone at the dealership said don't change it. The more you ask, the more you know

 

That helps, thanks. The Toyota shop manual wants the entire air cleaner assembly removed in the top. I'm really not sure why.

 

Awesome exactly what i needed. now only if you can explain the location with more pictures or manual maybe because im still confused about where exactly it is located.

 

The PCV valve is hiding under the intake manifold. That is why the OP had to go under the car for access to it.

 

It isn't clear why these cars should be more susceptible to PCV clogging than others. My last car went 600K miles on the original PCV valve, which never clogged or malfunctioned. Replacing it was not listed in the manufacturer's recommended maintenance schedule.

With a conventional PCV system, a plugged PCV valve (or excessive blowby) should lead to blowby gases exiting freely though the system's fresh-air intake plumbing, without building up significant pressure in the crankcase. I'm not sure whether there's something unconventional about the Prius in that respect.

 

it's not the prius, particularly, it's just a few members cars that seem to suffer. as patrick said, it may be due to short trips and the like. but your right, it isn't exactly clear why some have issues and others don't.

 

Holy cow, changing my PCV valve improved my mileage from the low 40's to near 50 mpg where it should be. I've been struggling to figure out why my mileage had gone into the dumpster for about five months. I bought my PCV valve from NAPA.

Some tips for changing it: I'll post pictures, but it can almost be done from the top if another item is removed. I ended up doing it from underneath. Yes, it is behInd the intake manifold on the block, but one can see the hose clamp from the front so it's almost exposed. Taking the air cleaner box out helps, but the air intake tube doesn't need to come out as shown in the Toyota shop manual. Use a deep 22 mm socket if you're cautious, but a deep ⅞" socket also works. The little nub sticking out of the block onto which the PCV valve mounts does not provide enough clearance for a closed-end wrench, and there's almost no room for an open-ended wrench. The valve body has about 1cm of thread, so with cramped access it takes a while to back it out. I think the threads are tapered like a pipe thread - when I started the new one into the hole, I could only do a couple of turns by hand. I watched the valve body as I tightened it into the block, and it did go in straight.

Pictures tomorrow.

 

Odometer reading?
Did you clean the PCV hoses with solvent?

 

74,336 miles, and the hose didn't seem to be very dirty.

 

wow!

 

Any clue how that's possible? Were there any other symptoms? Plugging of a PCV would tend to richen the fuel-air mixture slightly, but the fuel system should compensate.

With the engine idling, you should be able to get a rough idea whether the PCV system is functional by temporarily disconnecting the PCV intake hose and checking the net direction of flow. Air entering = OK. Blowby gases exiting = clogged system or excessive blowby. (That's assuming the Prius PCV system is essentially conventional, notwithstanding the unconventional valve location.)

 

another guy said his went from 40 - 50 by cleaning the injectors. who knows? seems like it can be anything with these cars.

 

Den, in another tank or two, you'll start relaxing your mpg technique, backslide to 48 mpg.

 

I'm still confused where the PCV is located; looking forward to more pictures!

Regarding "behind the intake manifold," what does behind mean ? Towards the rear of the car ?