What is this on 2008 5.3L?

[67C10BUB]

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

[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.

[67C10BUB]

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]

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

[TR65]

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]

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]

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

[Shon]

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

[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..

[67C10BUB]

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]

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

[tk-mpl]

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.
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[Shon]

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

[TR65]

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]

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]

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]

but that oil is going somewhere....

[68GMCCustom]

I plan on adding a catch can to mine

[TR65]

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]

Beter tell the GM engineers that..
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[Shon]

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

[68GMCCustom]

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