PCV Valve

[19963.4lsr5]

I wanted to bump this thread because I have a question about PCV valves and symptoms they cause when they fail.

Here's what I got:

Oil consumption
Oil leaks
poor mpg
rough start
slightly rougher idle
misfire under load mainly when trying to pass or accelerate up hills

Does this seem like a bad PCV valve?

When was the last time you did a tune up?


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[Mudeprived]

When was the last time you did a tune up?


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Spring of 2017.

 

[T4R2014]

I wanted to bump this thread because I have a question about PCV valves and symptoms they cause when they fail.

Here's what I got:

Oil consumption
Oil leaks
poor mpg
rough start
slightly rougher idle
misfire under load mainly when trying to pass or accelerate up hills

Does this seem like a bad PCV valve?

Two different 5VZ 4Runners. One had a rear main leak. I changed the PCV valve and it stopped leaking. The other would smoke when starting up. It was burning a quart every 500 miles as well. New PCV valve did the trick. I used NAPA Echlin in both cases, but I recommend OEM.

 

[Mudeprived]

Two different 5VZ 4Runners. One had a rear main leak. I changed the PCV valve and it stopped leaking. The other would smoke when starting up. It was burning a quart every 500 miles as well. New PCV valve did the trick. I used NAPA Echlin in both cases, but I recommend OEM.

I have a valve cover leak that is pretty bad but not sure about rear main cuz the whole backside is coated. I have a bad smoke show every morning and my oil level drops down to minimum mark at around 2500 miles.

I have a Toyota PCV and grommet arriving on Wednesday so I got my fingers crossed.

 

[T4R2014]

I have a valve cover leak that is pretty bad but not sure about rear main cuz the whole backside is coated. I have a bad smoke show every morning and my oil level drops down to minimum mark at around 2500 miles.

I have a Toyota PCV and grommet arriving on Wednesday so I got my fingers crossed.

Did the issue begin suddenly? Better hope your rings aren't shot.

 

[Mudeprived]

Did the issue begin suddenly? Better hope your rings aren't shot.

Hard to say. Too much happening over the past year.

This is a truck that was maintained with documents from day one though so if it is something serious then that would surprise me.

 

[T4R2014]

Hard to say. Too much happening over the past year.

This is a truck that was maintained with documents from day one though so if it is something serious then that would surprise me.

I get you. These things are so trouble-free that these sort of issues sneak up on you. Could be worse I guess. In that case I highly doubt your rings are bad, but sometimes shit has to happen in life. I don't think the PCV valve will affect idle and gas mileage, but who knows.

 

[BamaDrewski]

I have a valve cover leak that is pretty bad but not sure about rear main cuz the whole backside is coated. I have a bad smoke show every morning and my oil level drops down to minimum mark at around 2500 miles.

I have a Toyota PCV and grommet arriving on Wednesday so I got my fingers crossed.

I am sure you know this but when you got to change the PCV grommet, be holding a vacuum cleaner nozzle to the area to suck the old, brittle pieces up before they fall into the engine......those grommets get brittle as chalk over time and when you got to take em out, they crumble. Having a strong vacuum nozzle there gives you lots of "peace of mind" and much better than trying to find and pick out pieces after they have crumbled into the hole where the grommet is located....

 

[BamaDrewski]

I wanted to bump this thread because I have a question about PCV valves and symptoms they cause when they fail.

Here's what I got:

Oil consumption
Oil leaks
poor mpg
rough start
slightly rougher idle
misfire under load mainly when trying to pass or accelerate up hills

Does this seem like a bad PCV valve?

There are a lot of things (other than PCV) that could cause your symptoms. Based on my experience, I have found:

OIL CONSUMPTION: leaks somewhere...half moons, cam covers, VCG's, oil cooler gasket, seals.....

OIL LEAKS: See above

POOR MPG: clean the throttle body, MAF and get two new 02 sensors

ROUGH START: Spark plugs, MAF sensor

SLIGHTLY ROUGHER RIDE: TPS, MAF and 02's

MISFIRE UNDER LOAD: Plugs, Coilpacks, possible MAF, possibly TPS, and 02's

Keep in mind, when the 02's are crapping out, there is rarely a check engine light until they are totally non-functioning....

 

[Mudeprived]

There are a lot of things (other than PCV) that could cause your symptoms. Based on my experience, I have found:

OIL CONSUMPTION: leaks somewhere...half moons, cam covers, VCG's, oil cooler gasket, seals.....

OIL LEAKS: See above

POOR MPG: clean the throttle body, MAF and get two new 02 sensors

ROUGH START: Spark plugs, MAF sensor

SLIGHTLY ROUGHER RIDE: TPS, MAF and 02's

MISFIRE UNDER LOAD: Plugs, Coilpacks, possible MAF, possibly TPS, and 02's

Keep in mind, when the 02's are crapping out, there is rarely a check engine light until they are totally non-functioning....

Everything you mentioned except the TPS was replaced. The MAF was dirty and I cleaned it up. Weird thing was it drove fine to work after that but same shit started back up on way home. There are rare days where it starts up and runs normal and I chalked that up as one of them.

I had my mechanic run diagnostics and of course it started and ran normal that day. He could not duplicate the problem.

 

[Mudeprived]

I started reading up on PCV valves and what happens when they fail. Then I thought about a few odd things I have noticed like oil coming out of places that are unusual, such as the oil cap. I got oil coming out all around both VCG's and oil pan. I have a strong feeling that my PCV valve is stuck closed and pressure is forcing oil out everywhere.

 

[19963.4lsr5]

Your oil cap will leak even with a new PCV valve. The gasket crushes-shrinks-gets hard in the oil cap and it starts to leak. Replace the gasket.


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[Mudeprived]

Your oil cap will leak even with a new PCV valve. The gasket crushes-shrinks-gets hard in the oil cap and it starts to leak. Replace the gasket.


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I can see that happening but I have never seen an oil cap leak on any of my vehicles, and it leaking along with all the other gaskets appears to point to oil being forced out. Literally all my issues are pointing to a malfunctioning pvc.

What are the Symptoms of a Bad PCV VALVE?
The positive crankcase ventilation or PCV valve is an inexpensive and part most consumers overlook. It is also one of the possible causes of expensive oil leaks and sludge buildup inside the engine.

All automotive engines are lubricated with oil, and when oil is churned by moving parts, pressure is produced by combustion. Piston rings and valve guides also leak slightly producing pressure, called Blow-by, in the crankcase. Many years ago, the engines would simply vent the pressure into the atmosphere with a road-draft tube and breather cap. Today we use a positive crankcase ventilation or PCV system to handle this, and also to help lower the harmful emissions engines produce.

The most common problem that afflicts the PCV systems is a plugged up PCV valve or hose. Accumulation of fuel and oil varnish deposits and/or sludge inside the valve can restrict or even block the flow of vapors through the valve. A restricted or plugged PCV valve cannot pull moisture and blow-by vapors out of the crankcase. The valve can cause engine-damaging sludge to form and the backup of pressure that may force oil to leak past gaskets and seals. The loss of airflow through the valve can also cause the air/fuel mixture to run richer than normal, increasing fuel consumption and emissions. The same thing can happen if the pintle inside the PCV valve sticks shut.

If the pintle inside the PCV valve sticks open or the spring breaks, the PCV valve may flow too much air and lean out the idle mixture. The pcv may cause a rough idle, hard starting and/or lean misfire (which increases emissions and wastes fuel). The same thing can happen if the hose that connects the valve to the throttle body, carburetor or intake manifold pulls loose, cracks or leaks. A loose or leaky hose allows “un-metered” air to enter the engine and upset the fuel mixture, especially at idle where the idle mixture is most sensitive to vacuum leaks.

Rough idle, hard start, leaking seals, loss of mpg, oil consumption, misfiring. It might even explain the oil on the plug and in the throttle body.


I will find out tmw when the new pcv arrives.

 

[Rancho5]

You guys inspired me. Stopped by the dealer on the way home for a new valve and grommet.

 

[Mudeprived]

I was taking off the intake box to get better access to the PCV and noticed alot of oil coming from the tube in the picture. There was always a small puddle at the bottom of the intake tube. Does this tell a story?

I also removed the rubber grommet rather easily. I found it easier to make to slices, effectively cutting it in half, then using a pick and pliers to pull the halves out. A short suck of the hoover got the dirt particles that fell in.

It did not look pretty in there. Alot of baked on oil.

 

[19963.4lsr5]

If that PCV passage in the valve cover is clogged with coked oil it may be worth removing it and hitting it with a few cans of carb cleaner or soak the whole thing in a pan of mineral spirits.




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[Hammit]

Looks like I just found another high priority item for my main list:bolt:

 

[Rancho5]

You guys inspired me. Stopped by the dealer on the way home for a new valve and grommet.

And returning it... Just checked my repair log and I replaced it 5,000 miles ago. No idea how that slipped my mind. Getting old