Been working on my rough idle/stalling issues adn wehn I examined the throttle body it appeader to have quite a coting of oil inside it. Aftewr a little inspection figured out it was coming from the PCV hose attached to the passenger valve cover. My question is, is this normal?!? I am no greta mechanic but I don't think there should be oil getting into my air intake. After wiping out the throttle body the best I could the engine ran about 10 times better(although still not quite perfect). Any suggestions on why this is this and if I should do anything about it?

 

Mine has the oil film in there too. When I cleaned out the throttlebody it made no difference for me.

 

The passenger side plumbing to your throttle body works as a breather/vacuum. Your pvc is on the drivers side. I capped off the nipple from the throttle body and put on a breather cap on my passenger valve cover. Some people have experienced vacuum/idle problems from doing this.........I haven't.

I have head of others sucking oil into their throttle bodies and ultimetly into the plenum and down the runners.

 

gaudd,

I just rebuilt my LT4 and may have found a factory problem with the pcv stuff. My 'vette only had 64K whem I spun several bearing autoxing. I had previously noticed oil in my throttle body and wondered where it came from. When I took the motor apart I was shocked to see the cylinders choked with an oily/sooty black residue. I'm talking an honest 1/16" coating. I have some pic's of the cylinders posted on my webs site. http://www.buckmorris.com/LT4rebuild.htm

During the rebuild I keep looking for a reason the cylinders were choked. I found the problem when I cleaned up the intake manifold. The pcv is on the drivers side of the intake. There's a little black rubber hose with a 90 going from the pcv to the steel line that runs under the throttle body. I noticed the little black 90 was collapsed. Apparently the hose collapses under vaccum when new and over time and heat just stays collapsed. I bent a 90 out of copper then coated it with Seal-Rite and slid it into the hose to keep it open. I left enough room at each end to re-attach it to the steel line and the pcv valve. Its seems to be working just fine. I can feel the valve vibrating when the engine is running.

You didn't mention what year you have but I'm sure the collapsed hose was letting the crank case pressurize and vent vapors directly into the TB on my 'vette.

Buck.

 

well, after doing a little research on older posts I am thinking that doing the PCV mod that the C5 guys have been doing would be the way to go to avoid any vacuum issues. thanks for the help guys


[Modified by gaudd, 10:27 PM 3/10/2003]

 

:iagree: im still trying to figure out how to do it on mine... question. A collapsed Elbow, wouldnt that mean that it wouldn't allow the fumes to be drawn into the intake?? my picture in my head of how this works just isnt registering. WOuld a breather help??? For high hp motors will a valve cover breather be the better way or the breather and the pcv mod??

clueless... my car has no motor in it... in the garage so i cant go look at it.. help me out guys :crazy:

 

Thanks for the reply. Mine is actually a 1990 L98 so I am not sure just similar it is. I was checking out your website and noticed you were from near Stillwater. That's where I live. Maybe we can hook up and go racing some time once I get my car running up to snuff. I could use someone with a little experience as this is my first 'real' car.

 

Sounds good to me. Here's the web sites for the region's. http://www.neokla-scca.org and http://www.okscca.org. Follow the Solo II links to the schedule page. The next event is 03/25.

I do some open track (high speed touring) at Hallett as well. http://www.hallettracing.com/

Buck.

 

So maybe a breather on the pcv line would help reduce crankcase pressure?

I have this problem also. I'm looking for a pcv diagram somewhere...

:lurk: