Drill out larger holes in PCV Valve??? - TerrainForum.net: GMC Terrain Forum
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post #1 of 10 (permalink) Old 09-26-2019, 12:31 PM Thread Starter
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Drill out larger holes in PCV Valve???

Ordered a new 12583384 PCV valve for my 2011 GMC Terrain 3.0L.

Should I just replace it, or should I first drill out the holes in the new PCV valve to 7/64" on the top and 5/64" on the 2 bottom holes? Thoughts?

Thanks

2011 GMC Terrain 3.0L AWD
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post #2 of 10 (permalink) Old 09-26-2019, 12:39 PM
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I thought this is only a 4 cyl issue, not with the 6 cyl.

2018 Equinox LT1 1.5 L 4 cyl, AWD, S/R Cajun Red Tintcoat/Black

2010 Equinox LTZ 2.4 L 4 cyl, FWD, S/R Cardinal Red/Black
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post #3 of 10 (permalink) Old 09-26-2019, 01:38 PM
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On the 3.0 and 3.6, the holes get clogged. Leads to oil buildup in the air tube. If it gets severe enough- you get the milkshake in the tube. You will also get oil on the Throttle body.
This is worse for folks in Cold weather.
What will happens is the milkshare and moisture in the TB area will Freeze. (I believe it freezes and the butterfly will not move)

This will cause the vehicle to go into Limp Mode- at the worst time--- usually when its snowing and freezing.


THe big clue-- is that most folks indicate- they have to pull over. Some call tow truck etc.
But a while later- the vehicle runs fine for tow truck driver-- or for a drivers who has gone out to investigate.


What happens is the engine blocks heat- while vehicle is stopped/turned off--- will melt the ice buildup... and when they restart--- vehicle is fine.
and operates fine.

This will repeat if conditions are similar.


So before winter arrives- I recommend folks to clean the throttle body and tube.


On my 2010 I did indeed remove the part- and install a new unit with drilled out holes. No more oil pooling since the mod.


there are pics here of my mod- and other members.


https://www.traverseforum.com/33-eng...re-thread.html

2013 Equinox LT1 3.6L V6 FWD 88,000
2010 Traverse LT1 3.6L V6 FWD 153,000
2003 Trailblazer LS 4.2L I6 RWD 181,000
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post #4 of 10 (permalink) Old 09-26-2019, 09:43 PM
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DeBoy,
Don't drill them out......
I believe,....
Crankcase pressure is caused by piston blowby

Drilling the larger holes in "dirty side" PCV orifice on your V6
Will lower crankcase pressure a little bit
Drilling the larger holes in orifice , will REDUCE the "crankcase gunk that backs up your cleanside PCV breather hose which will reduce oil in your air intake plenum (just beyond your air filter and before throttle body)
... Drilling larger holes will reduce, but not eliminate crankcase pressure, such as during wide open throttle
or if you have really worn piston rings
In those cases crankcase pressure will still push crankcase gunk up through you cleanside PCV hose in order to relieve crankcase pressure
BUT
Drilling larger dirty side PCV holes
Will give you will get more intake valve carbon build up ( the enemy of every gdi engine)
And you will get more oil in intake manifold ( beyond the throttle body)
because more crankcase gunk will flow thru the bigger holes in the dirty side PCV ....
(If you drill holes you might need to install the new redesigned valve cover gasket that also has splash shield to protect the larger holes from oil splash ?)
OR
(unless you have a catch can to catch the gunk that flows thru the larger holes !)

Instead
I would get the $80 vented oil cap,
Which keeps crankcase at a nice zero (or negative) psi pressure.
At zero PSI crankcase pressure no crankcase gunk will ever be pushed up your cleanside PCV hose and when crankcase is at negative pressure (vacuum) clean air will flow from your air intake plenum, via clean side PCV hose, into crankcase as it should.

Problem solved!!!!
In fact.... with the vented cap....
why not leave the dirty "dirty side" with small holes PCV in the engine, the fact that the holes are gunked up, means, will less crankcase gunk will flow thru it,
Resulting in less carbon build on intake valves...

2012 Traverse with Elite E2 X catchcan
Three Equinox with 2.4 engine, 2013, 2016 and 2016
2017 equinox with 3.6 engine with Elite E2 X catchcan
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post #5 of 10 (permalink) Old 09-26-2019, 09:59 PM
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RIT333

The 6 cylinder has a dirty side PCV orifice (with 3 holes) and a hose which connects dirty side PCV orifice to the intake manifold after the throttle body.
If you wanted to install a catch can you would cut this hose and splice in the catch can

The 4 cylinder has an internal PCV orifice, a single hole molded into the intake manifold. You can not install a catch can since this dirty side PCV is internal, inside the engine.

Both engines V6 and 4, have an external clean side PCV breather that supplies clean air into crankcase from air intake plenum ( just beyond air filter)
And
under wide open throttle or when piston rings are worn so lots of piston blow by all the time
Then crankcase pressure also relieves itself via cleanside PCV hose and crankcase gunk flows out cleanside PCV hose and into air intake plenum.

On 4 cylinder equinox, the small diameter cleanside hose can freeze solid in winter, which then might result in rear main seal failure if crankcase pressure gets high enough !!!!
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2012 Traverse with Elite E2 X catchcan
Three Equinox with 2.4 engine, 2013, 2016 and 2016
2017 equinox with 3.6 engine with Elite E2 X catchcan
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post #6 of 10 (permalink) Old 09-26-2019, 11:49 PM
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You could just get a PCV valve for the 2017 model V-6.
Supposedly the holes are larger.


My 2
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post #7 of 10 (permalink) Old 09-27-2019, 12:05 PM
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thats what I read too- that GM began to put in PCV with larger holes-- since the earlier ones were clogging up
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2013 Equinox LT1 3.6L V6 FWD 88,000
2010 Traverse LT1 3.6L V6 FWD 153,000
2003 Trailblazer LS 4.2L I6 RWD 181,000
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post #8 of 10 (permalink) Old 10-02-2019, 09:04 AM Thread Starter
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Thanks for the replies. Still not sure if I will drill out the holes or not. When I remove the old one, I will see how clogged it looks.

2011 GMC Terrain 3.0L AWD
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post #9 of 10 (permalink) Old 10-02-2019, 10:54 AM
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Quote:
Originally Posted by deboy922 View Post
Thanks for the replies. Still not sure if I will drill out the holes or not. When I remove the old one, I will see how clogged it looks.

some folks have soaked it- in cleaner and reinstalled...
But may be better to just order a new one--- remove the old- and pop in the new one.
THe old ones will get a little banged up from being removed.. like pliers/vice grips etc.

2013 Equinox LT1 3.6L V6 FWD 88,000
2010 Traverse LT1 3.6L V6 FWD 153,000
2003 Trailblazer LS 4.2L I6 RWD 181,000
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post #10 of 10 (permalink) Old 10-04-2019, 03:47 PM Thread Starter
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Quote:
Originally Posted by rbarrios View Post
some folks have soaked it- in cleaner and reinstalled...
But may be better to just order a new one--- remove the old- and pop in the new one.
THe old ones will get a little banged up from being removed.. like pliers/vice grips etc.
Thanks...new one delivered last night.

2011 GMC Terrain 3.0L AWD
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