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2012 GMC Terrain 3.0L V6 Valve Cover Replacement

Posted By: benjamming

2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 01:30 AM

2012 Terrain 3.0L V6 flex fuel engine with 207k miles
Oil was in one of the spark plug tubes (middle front cylinder - didn't look up the #). Not much oil but noticeable. Next step it would naturally seem (intake manifold already off) is to replace the valve cover gaskets & spark plug tube seals. What is the valve cover bolt torque spec?

Also, I found the below when reading up some on this problem. Anyone have the bulletin where this was issued? My first step is to rule out the valve cover gasket & spark plug tube seals, but this is looming. Vehicle sets a general misfire code every week or so but no driveability issues yet.

Fluid in Spark Plug Tubes
March 25, 2013

A Check Engine light may be illuminated with misfire DTCs set, or a possible oil or coolant leak may be found, on some 2010-2013 Enclave, LaCrosse, CTS, SRX, Camaro, Equinox, Traverse, Acadia, Terrain; 2012-2013 Caprice PPV, Captiva, Impala; 2013 ATS and XTS models equipped with 3.0L and 3.6L (RPOs LF1, LFW, LLT, LFX) HFV6 engines. (Fig. 10)
On inspection, coolant or oil may be found in a spark plug tube. Determine if the oil or coolant is coming from the spark plug tube and not leaking into it from above. If the spark plug tube is leaking, replace the cylinder head, spark plug and coil.
Porous spots in the head created during manufacturing cause the leak. The spark plug tubes are permanently sealed into the head and are not replaceable.
If a cylinder head is replaced for this condition, mark the faulty spark plug tube before sending the head in for warranty or core so GM Engineering or the re-manufacturing facility can identify it.
Posted By: JTK

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 01:55 AM

Yikes. "Replace the cylinder head" can't be a pleasant job on these.
Posted By: Chris142

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 02:00 AM

Junk
Posted By: dishdude

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 02:14 AM

Originally Posted by Chris142
Junk


You should really reconsider giving such helpful advice away for free.

It's normal for the bottom part of the tube to be part of the head, but the top that seals with the VC should be replaceable. At 207k, it's pretty safe to say you don't have a porous head.
Posted By: double vanos

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 02:39 AM

I say put it back together and keep on motoring.
Posted By: benjamming

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 02:45 AM

Yep, plan on keeping it going, but would like the valve cover torque value to minimize leakage issues later.
Posted By: super20dan

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 03:17 AM

I agree these cars are junk. everything gm makes is junk except the fullsized trucks
Posted By: BTLew81

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 04:08 AM

Originally Posted by super20dan
I agree these cars are junk. everything gm makes is junk except the fullsized trucks


Value added post....filled with fact.
duh
Posted By: dogememe

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 04:31 AM

Originally Posted by Chris142
Junk

It has 200k miles. A leaky valve cover gasket at that mileage isn't junk, it's normal.
Posted By: 4WD

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 04:38 AM

Yeah … impressive
Posted By: gregk24

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 05:17 AM

Originally Posted by Chris142
Junk


Wow, that was helpful. 207K miles seems like a good run to me.
Posted By: demarpaint

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 11:45 AM

Originally Posted by gregk24
Originally Posted by Chris142
Junk


Wow, that was helpful. 207K miles seems like a good run to me.

Seems like a good run to me too.
Posted By: MrHorspwer

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 01:02 PM

Originally Posted by benjamming

Fluid in Spark Plug Tubes
March 25, 2013

A Check Engine light may be illuminated with misfire DTCs set, or a possible oil or coolant leak may be found, on some 2010-2013 Enclave, LaCrosse, CTS, SRX, Camaro, Equinox, Traverse, Acadia, Terrain; 2012-2013 Caprice PPV, Captiva, Impala; 2013 ATS and XTS models equipped with 3.0L and 3.6L (RPOs LF1, LFW, LLT, LFX) HFV6 engines. (Fig. 10)
On inspection, coolant or oil may be found in a spark plug tube. Determine if the oil or coolant is coming from the spark plug tube and not leaking into it from above. If the spark plug tube is leaking, replace the cylinder head, spark plug and coil.
Porous spots in the head created during manufacturing cause the leak. The spark plug tubes are permanently sealed into the head and are not replaceable.
If a cylinder head is replaced for this condition, mark the faulty spark plug tube before sending the head in for warranty or core so GM Engineering or the re-manufacturing facility can identify it.


This isn't from a TSB. This is from what GM calls a PI, or Preliminary Information.

By law, TSBs are required to be published as public knowledge. Anyone can access them for free. A PI is like an internal TSB. A PI can only be viewed by associates within the manufacturer's service organization. They are not freely published. All manufacturers have a similar system, not just GM.

Often, a PI may precede a TSB when the manufacturer is looking for more information on a specific issue or trying to scope a concern. Sometimes they'll even have the phone number of an engineer to call if you have a vehicle with the described condition. Like I said, they're intended for professionals within the manufacturer's service organization.

In other cases, as PI is written to provided specific instructions as it relates to servicing within the manufacturer's service administration. I think this is the case here. Looking at the PI, it's actually applicable for every single vehicle equipped with a 3.0L or 3.6L V6 from 2010 to 2019. This are different engine RPOs manufactured in different locations, using different castings, etc. There is nothing common about the engines involved. That's because the PI isn't necessarily about the oil/coolant leak issue, it's about what the manufacturer wants the technician to do when they find the issue:
Quote
If a cylinder head is replaced for this condition, mark the faulty spark plug tube before sending the head in for warranty or core so GM Engineering or the re-manufacturing facility can identify it.

That integrated spark plug tube may be in an awkward location that magnaflux testing doesn't show very well during the re-manufacturing and visible identification may be difficult after cleaning. They're asking techs to mark it so the re-manufacturer knows to specifically looks there. Again, not something the general public needs to know, but if you're in the business of selling warranty cores to re-manufacturers, that's a different story.

Posted By: bullwinkle

Re: 2012 GMC Terrain 3.0L V6 Valve Cover Replacement - 12/07/19 01:18 PM

Originally Posted by dishdude
Originally Posted by Chris142
Junk


You should really reconsider giving such helpful advice away for free.

It's normal for the bottom part of the tube to be part of the head, but the top that seals with the VC should be replaceable. At 207k, it's pretty safe to say you don't have a porous head.

I have to agree with try a gasket & keep going, at 207K it's ahead of the curve. Better than Ford! (& no, I'm not going into detail for the millionth time!) crazy
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