ausmini :: View topic - Engine idles faster.. PCV?

Does your car have a sealed oil cap or a vented oil cap? I think it should have a vented oil cap.
The vented cap lets clean air into the crankcase at a restricted rate.

I have used PCVs with sealed caps and filtered caps, they usually work OK with either. :wink:

drmini in aust wrote:

I have used PCVs with sealed caps and filtered caps, they usually work OK with either. :wink:

The only possible problem is if there is too much vacuum and it sucks the rocker cover gasket in (like it did on my old Torana) :lol:

What was the problem in the first place?

if it aint broke :wink:

> if you go looking for faults you can usually find them

Author:	MG Rocket [ Tue Sep 29, 2009 5:13 pm ]
Post subject:	Engine idles faster.. PCV?
With the engine running..I take the unvented oil cap off....the revs immediately pick up....if I take the hose to the PVC off the revs pick up......so is the PVC not working?

Author:	Morris 1100 [ Tue Sep 29, 2009 5:41 pm ]
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That means it is working.

Author:	MG Rocket [ Tue Sep 29, 2009 6:01 pm ]
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So what suppresses the idle.....crankcase pressure? And at what revs should I expect the valve to open?

Author:	Morris 1100 [ Tue Sep 29, 2009 7:16 pm ]
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The valve is open, that is why the idle increases. If the valve was closed the idle would stay the same. The idea is to keep the cranckcase pressure low or even a partial vacuum. Does your car have a sealed oil cap or a vented oil cap? I think it should have a vented oil cap. The vented cap lets clean air into the crankcase at a restricted rate.

Author:	MG Rocket [ Tue Sep 29, 2009 8:00 pm ]
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Morris 1100 wrote: Does your car have a sealed oil cap or a vented oil cap? I think it should have a vented oil cap. The vented cap lets clean air into the crankcase at a restricted rate. It has a sealed cap.

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Author:	drmini in aust [ Tue Sep 29, 2009 8:10 pm ]
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I have used PCVs with sealed caps and filtered caps, they usually work OK with either.

Author:	Morris 1100 [ Tue Sep 29, 2009 8:14 pm ]
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drmini in aust wrote: I have used PCVs with sealed caps and filtered caps, they usually work OK with either. The only possible problem is if there is too much vacuum and it sucks the rocker cover gasket in (like it did on my old Torana)

Author:	goodie [ Tue Sep 29, 2009 8:49 pm ]
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My 1310 does the same thing , has done so for 10 years, nothing to worry about. Colin

Author:	drmini in aust [ Tue Sep 29, 2009 9:35 pm ]
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Keep an eye on the rubber diaphragm in the PCV valve. The ones they sell now go hard in a few years, then the valve can't work properly.

Author:	Tombo [ Tue Sep 29, 2009 9:46 pm ]
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Morris 1100 wrote: drmini in aust wrote: I have used PCVs with sealed caps and filtered caps, they usually work OK with either. The only possible problem is if there is too much vacuum and it sucks the rocker cover gasket in (like it did on my old Torana) I've heard crank seals make strange noises due to too much crank case vacuum.

Author:	MG Rocket [ Wed Sep 30, 2009 6:07 pm ]
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I disconnected and plugged the PVC and vented the vent to the atmosphere. The car ran much smoother and the idle more stable. The downside was the fumes.....I think I got lung cancer from the trip. There has always been a nice sheen of fresh oil over the southern end of the head and block. It would seem presure is building up in the block. So one would have to think there is problem with the PVC.....wouldn't you?

Author:	Morris 1100 [ Wed Sep 30, 2009 6:09 pm ]
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What was the problem in the first place?

Author:	MG Rocket [ Wed Sep 30, 2009 6:17 pm ]
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Morris 1100 wrote: What was the problem in the first place? Well I didn't know there was a problem...It was that I noticed the idle picked up VERY noticeably when I took the oil cap off.....and thought that can't be right. When I unplugged the PVC the same thing although the revs picked up it was a bit rougher, obviously sucking some air but not enough to stall. I could never get a good idle.....blamed the carbies......but now I get a good idle.

Author:	Blokeinamoke [ Wed Sep 30, 2009 6:20 pm ]
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if it aint broke > if you go looking for faults you can usually find them

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Author:	MG Rocket [ Wed Sep 30, 2009 6:24 pm ]
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blokeinamoke wrote: if it aint broke > if you go looking for faults you can usually find them I think it was broke....I just not smartyenuff to know