What is this on 2008 5.3L? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67C10BUB · 09-05-2010, 11:33 PM

Can anyone tell me what this tube is for? It is on the passenger side head.

tk-mpl · 09-06-2010, 04:58 AM

I think it is the PCV. I just routed mine into the air intake tube. I know it goes into the intake on the stock truck.

67C10BUB · 09-06-2010, 01:00 PM

Quote:

Originally Posted by tk-mpl

I think it is the PCV. I just routed mine into the air intake tube. I know it goes into the intake on the stock truck.

Did you use the stock intake duct? If not, how did you hook it up?

**LEEVON** · 09-06-2010, 05:43 PM

I know it's routed into the intake because I had to relocate it when I put a different intake on.

**TR65** · 09-06-2010, 08:34 PM

LEEVON

That hose supplies filtered and measured air to the crankcase. It is sucked out on the other side of the engine and into the intake by the intake vacuum thru an orifice tube. That makes up the PCV system.

Since the tube takes in air after the MAF the total air intake into the cylinders is all accounted for.

TR

**TR65** · 09-06-2010, 08:57 PM

On second look that tube seems to be after the throttle body in which case I guess it would be the air from the crankcase to the intake.

I have an 2005 and a 2008 that work like I said in the first post.

There should be one tube to the intake from usually the drivers side head for crankcase ventilation.

There should be one tube feeding measured and filtered air to usually the passenger side head to supply the crankcase.

There is the vapor return line from the tank to the intake

There is the vacuum line from the intake to the brake booster.

That should be it.

TR

67C10BUB · 09-06-2010, 10:42 PM

Thanks for the help everyone. I guess I'll have to figure out a way to plumb it into my intake.

Shon · 09-07-2010, 10:58 AM

I take it off and put a breather on the VC and cap off the intake.

tk-mpl · 09-08-2010, 01:06 AM

I just heated the end of that plastic pipe alittle and pulled the end off. The I just put a 3/8 barp in the intake tube..

67C10BUB · 09-08-2010, 05:38 AM

Quote:

Originally Posted by tk-mpl

I just heated the end of that plastic pipe alittle and pulled the end off. The I just put a 3/8 barp in the intake tube..

Good idea. I'll have to see if I can find a thread-through barb fitting. Any idea where you got yours?

Shon · 09-08-2010, 07:35 AM

not such a good idea. where is the oil going??? cap it off and put breather on VC.

tk-mpl · 09-08-2010, 09:59 AM

You can get a fitting at any parts store....

Shon, there shouldn't be any oil there and that is exactly where it goes in the factory intake.
Posted via Mobile Device

Shon · 09-08-2010, 10:04 AM

Let it run like that or the factory way and pull intake after a little while and let me know what you find.

**TR65** · 09-08-2010, 09:33 PM

Guys,

That tube supplies air to the crankcase. It is sucked out of the other head into the intake mainfold by vacuum.

If you are building up enough crankcase pressure to push oil up that tube it seems like something must be wrong.

I have seen people even put oil separators on that line but I don't get it. Is that something that happens with continuous high revving??

TR

68GMCCustom · 09-08-2010, 10:52 PM

the efi throttle bodys do have a tendency to get very dirty/carboned up....and some say that its due to sucking up oil....and that those catch cans help. Generally hard use situations tho I think...

Ackattack · 09-09-2010, 01:24 AM

I put some cast aluminum valve covers on my engine, so that eliminated the PCV location that is on the stock valve covers. Initially I tried running just 2 breathers (one on each valve cover) but I was getting oil dripping out of one of the breathers, so I put a regular PCV valve in the pass. head and routed it to the intake and no more dripping oil.

Shon · 09-09-2010, 07:45 AM

but that oil is going somewhere....

68GMCCustom · 09-09-2010, 10:25 AM

I plan on adding a catch can to mine

**TR65** · 09-10-2010, 08:55 PM

Well,

I talked to a real mechanic today and he said that at high RPM wide open throttle with a worn engine the blow by pressure can get high enough to reverse the flow and drive oil up inlet tube. So I guess that is the deal.

TR

tk-mpl · 09-10-2010, 09:11 PM

Beter tell the GM engineers that..
Posted via Mobile Device

Shon · 09-10-2010, 09:16 PM

it happens from day one on most of them....

68GMCCustom · 09-10-2010, 09:25 PM

this is not a "worn motor" issue. I've had a new '01 LQ4 and have a new '06 LS2 that both do it.

09-05-2010, 11:33 PM	#1
67C10BUB Registered User Join Date: Aug 2010 Location: Alta Loma, CA Posts: 610	What is this on 2008 5.3L? Can anyone tell me what this tube is for? It is on the passenger side head. Attached Images

09-06-2010, 04:58 AM	#2
tk-mpl Registered User Join Date: Jan 2008 Location: Lacombe, Alberta Posts: 353	Re: What is this on 2008 5.3L? I think it is the PCV. I just routed mine into the air intake tube. I know it goes into the intake on the stock truck. __________________ 1968 short box stepside. 2007 5.3L 4L60, tuned w/EFI Live 2005 Silverado bucket seats. Dominator 2600's all around. Porterbuilt tubular control arms. Magnaflow 3" dual exhaust.

09-06-2010, 05:43 PM	#4
LEEVON Moderator Join Date: Jul 2006 Location: Ozark, MO Posts: 4,888	Re: What is this on 2008 5.3L? I know it's routed into the intake because I had to relocate it when I put a different intake on. __________________ '20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids

09-06-2010, 08:34 PM	#5
TR65 Senior Member Join Date: Nov 2007 Location: Greenville, SC Posts: 873	Re: What is this on 2008 5.3L? LEEVON That hose supplies filtered and measured air to the crankcase. It is sucked out on the other side of the engine and into the intake by the intake vacuum thru an orifice tube. That makes up the PCV system. Since the tube takes in air after the MAF the total air intake into the cylinders is all accounted for. TR __________________ 1965 C10 SWB Fleet Two owner LS2 Swap Thread http://67-72chevytrucks.com/vboard/s...d.php?t=413880

09-06-2010, 08:57 PM	#6
TR65 Senior Member Join Date: Nov 2007 Location: Greenville, SC Posts: 873	Re: What is this on 2008 5.3L? On second look that tube seems to be after the throttle body in which case I guess it would be the air from the crankcase to the intake. I have an 2005 and a 2008 that work like I said in the first post. There should be one tube to the intake from usually the drivers side head for crankcase ventilation. There should be one tube feeding measured and filtered air to usually the passenger side head to supply the crankcase. There is the vapor return line from the tank to the intake There is the vacuum line from the intake to the brake booster. That should be it. TR __________________ 1965 C10 SWB Fleet Two owner LS2 Swap Thread http://67-72chevytrucks.com/vboard/s...d.php?t=413880

09-06-2010, 10:42 PM	#7
67C10BUB Registered User Join Date: Aug 2010 Location: Alta Loma, CA Posts: 610	Re: What is this on 2008 5.3L? Thanks for the help everyone. I guess I'll have to figure out a way to plumb it into my intake.

09-07-2010, 10:58 AM	#8
Shon Registered User Join Date: Sep 2005 Location: sc Posts: 1,203	Re: What is this on 2008 5.3L? I take it off and put a breather on the VC and cap off the intake. __________________ 71 Cheyenne C10 LWB cam'd 6.0/T56 Swap

09-08-2010, 01:06 AM	#9
tk-mpl Registered User Join Date: Jan 2008 Location: Lacombe, Alberta Posts: 353	Re: What is this on 2008 5.3L? I just heated the end of that plastic pipe alittle and pulled the end off. The I just put a 3/8 barp in the intake tube.. Attached Images __________________ 1968 short box stepside. 2007 5.3L 4L60, tuned w/EFI Live 2005 Silverado bucket seats. Dominator 2600's all around. Porterbuilt tubular control arms. Magnaflow 3" dual exhaust.

09-08-2010, 07:35 AM	#11
Shon Registered User Join Date: Sep 2005 Location: sc Posts: 1,203	Re: What is this on 2008 5.3L? not such a good idea. where is the oil going??? cap it off and put breather on VC. __________________ 71 Cheyenne C10 LWB cam'd 6.0/T56 Swap

09-08-2010, 09:59 AM	#12
tk-mpl Registered User Join Date: Jan 2008 Location: Lacombe, Alberta Posts: 353	Re: What is this on 2008 5.3L? You can get a fitting at any parts store.... Shon, there shouldn't be any oil there and that is exactly where it goes in the factory intake. Posted via Mobile Device __________________ 1968 short box stepside. 2007 5.3L 4L60, tuned w/EFI Live 2005 Silverado bucket seats. Dominator 2600's all around. Porterbuilt tubular control arms. Magnaflow 3" dual exhaust.

09-08-2010, 10:04 AM	#13
Shon Registered User Join Date: Sep 2005 Location: sc Posts: 1,203	Re: What is this on 2008 5.3L? Let it run like that or the factory way and pull intake after a little while and let me know what you find. __________________ 71 Cheyenne C10 LWB cam'd 6.0/T56 Swap

09-08-2010, 09:33 PM	#14
TR65 Senior Member Join Date: Nov 2007 Location: Greenville, SC Posts: 873	Re: What is this on 2008 5.3L? Guys, That tube supplies air to the crankcase. It is sucked out of the other head into the intake mainfold by vacuum. If you are building up enough crankcase pressure to push oil up that tube it seems like something must be wrong. I have seen people even put oil separators on that line but I don't get it. Is that something that happens with continuous high revving?? TR __________________ 1965 C10 SWB Fleet Two owner LS2 Swap Thread http://67-72chevytrucks.com/vboard/s...d.php?t=413880

09-08-2010, 10:52 PM	#15
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: What is this on 2008 5.3L? the efi throttle bodys do have a tendency to get very dirty/carboned up....and some say that its due to sucking up oil....and that those catch cans help. Generally hard use situations tho I think... __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

09-09-2010, 01:24 AM	#16
Ackattack Senior Member Join Date: Aug 2002 Location: Valley Center KS Posts: 3,524	Re: What is this on 2008 5.3L? I put some cast aluminum valve covers on my engine, so that eliminated the PCV location that is on the stock valve covers. Initially I tried running just 2 breathers (one on each valve cover) but I was getting oil dripping out of one of the breathers, so I put a regular PCV valve in the pass. head and routed it to the intake and no more dripping oil. __________________ Project Bruiser: 68 Pro-Touring C-10 5.3L / 4L60E Project Ironhide: 97 GMC Crew Cab 4x4 Cummins SOLD: '69 GMC 1/2T SWB TBI'd: Project No Buck Assembly Manual Index Sign up Thread!!! Factory Service Manual Index

09-09-2010, 07:45 AM	#17
Shon Registered User Join Date: Sep 2005 Location: sc Posts: 1,203	Re: What is this on 2008 5.3L? but that oil is going somewhere.... __________________ 71 Cheyenne C10 LWB cam'd 6.0/T56 Swap



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09-09-2010, 10:25 AM	#18
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: What is this on 2008 5.3L? I plan on adding a catch can to mine __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

09-10-2010, 08:55 PM	#19
TR65 Senior Member Join Date: Nov 2007 Location: Greenville, SC Posts: 873	Re: What is this on 2008 5.3L? Well, I talked to a real mechanic today and he said that at high RPM wide open throttle with a worn engine the blow by pressure can get high enough to reverse the flow and drive oil up inlet tube. So I guess that is the deal. TR __________________ 1965 C10 SWB Fleet Two owner LS2 Swap Thread http://67-72chevytrucks.com/vboard/s...d.php?t=413880

09-10-2010, 09:11 PM	#20
tk-mpl Registered User Join Date: Jan 2008 Location: Lacombe, Alberta Posts: 353	Re: What is this on 2008 5.3L? Beter tell the GM engineers that.. Posted via Mobile Device __________________ 1968 short box stepside. 2007 5.3L 4L60, tuned w/EFI Live 2005 Silverado bucket seats. Dominator 2600's all around. Porterbuilt tubular control arms. Magnaflow 3" dual exhaust.

09-10-2010, 09:16 PM	#21
Shon Registered User Join Date: Sep 2005 Location: sc Posts: 1,203	Re: What is this on 2008 5.3L? it happens from day one on most of them.... __________________ 71 Cheyenne C10 LWB cam'd 6.0/T56 Swap

09-10-2010, 09:25 PM	#22
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: What is this on 2008 5.3L? this is not a "worn motor" issue. I've had a new '01 LQ4 and have a new '06 LS2 that both do it. __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

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