Oil in intake...

[BlackFox5.0]

I noticed that my TB is cucking in Oil from the valve cover tube.... is there a way to stop this, or should I plug the tube?

I guess that explains why I was down 3/4 a quart after 3000 miles.....

I have the motorsport valve covers, but they have the oil baffle under the oil fill stem.

 

[5.0's 4 ever]

You could eliminate the tube all together. Run a breather cap on the valve cover and cap off the fitting on the throttle body.

 

[Mustang5L5]

Cap off both fittings and run a breather tube.

 

[BlackFox5.0]

I heard that breathers allow unmetered air into the engine, causing problems....

 

[IndyBlk5.0]

very little unmetered air IMO, pcv valve generally causes oil to be sucked into the runners of the intake, this could be your problem. really bad with cobra style intakes. i had oil in mine the first day i drove mine fresh, tore it apart, oil in runners... pcv is the problem with me....

 

[BlackFox5.0]

Believe it or not, but I pulled the hose from the PCV off on the intake side, and there was no oil in it.

The line that goes to the TB has oil all inside it, and if you look in the intake through the TB there is oil....so it is definately coming from the filler neck.

 

[IndyBlk5.0]

I have the motorsport valve covers, but they have the oil baffle under the oil fill stem.

Cap off both fittings and run a breather tube.

definately coming from the filler neck

well, the only way is to do like mustang5l5 said, if you have a baffle in there allready, you will have to run a breater to stop this...

 

[Michael Yount]

There are other ways to deal with it. First you need to be certain that your pcv valve, hose and trap (metal screen under the valve) are all clean and working properly. If they are, then when the engine's creating vacuum -- most of the time on the street -- the air in the hose between the throttle body and valve cover is moving TOWARDS the engine, not the other way around. The intake sucks air through the pcv from the crankcase. The trap and valve (and the baffle under the back half of the GT40 lower) are all there to minimize the engine pulling oil into the intake. The air that gets pulled into the intake has to enter the engine from somewhere - and that's what the hose between the valve cover and the throttle body are there for. Air that is already metered through the maf enters the manifold via the valve cover/crankcase/pcv valve route. When vacuum isn't present in the manifold, crankcase pressure must be vented. Assuming the pressure in the crankcase is greater than atmospheric pressure - and it is when you're into the throttle hard - then the crankcase pressure gets vented into manifold via the pcv valve, and the line between the valve cover and the throttle body. So that little hose provides bi-directional air flow. If the pcv system isn't doing it's job letting air flow, more crankcase pressure -- along with the oil vapor in that air -- is allowed into the throttle body when you're hard on the throttle. This is the source of oil in the throttle body.

So, be certain the pcv system is doing it's job. If you want more protection still, install catch cans between the 1) pcv valve and manifold, and 2) between the valve cover nipple and the throttle body. These cans can be configured to knock out and catch oil so that less of it reaches the intake and the throttle body. If you'd like to see pics, pm me with your email address, and I'll take some pics of my set up for you. I've got catch cans installed between both - it minimizes oil in the intake, but it keeps the pcv system functional so those raw oil-laden vapors aren't going to the atmosphere (an emissions problem) or making a mess all over the top of your engine.

The whole discussion above assumes the engine is naturally aspirated. If you've got boost pressure, then precautions must be taken so that boost pressure doesn't pressurize the crankcase. What works best there seems to be venting the crank case by 1) check valves in the pcv system designed to withstand boost pressure, 2) venting the catch can, or 3) plumbing the crankcase/valve cover nipple into the inlet side of the supercharger with a catch can in between.

In my opinion, the least elegant solution of all is putting a breather on the valve cover. While it may solve the problem, they make a mess, they foul the air, they're not emissions legal, and they allow unmetered air to enter the engine. More detail than you wanted no doubt.....

 

[Michael Yount]

Oh - blackfox - if the pcv line has no oil in it, it could be because the screen underneath the valve is clogged up allowing very little air to be pulled from the crankcase. This will force more vapor/oil through the throttle body line when you're hard on the gas.

 

[BlackFox5.0]

That was some good info Michael, I always thought air was sucked through the valve cover and into the TB....

The metal sceen under the PCV is brand new, and the PCV worked when I tested it. I do tend to get on the throttle every now and then just to feel the power (hehe )

I do not want to run a breather, although your catch can sounds like a good idea, I would like to see some pic of it to see if it looks like I am imagining. my e-mail is [email protected]

 

[Michael Yount]

Chris - headed out to Sunday brunch; I'll save the email and try to get some pics to you later today.

 

[Schlodes]

I still owe Micheal Yount for explaining how this PCV stuff works to me last fall.

See, I bought a 65mm T body that does not have the provision on it for that tube that runs from the T body to the oil fill tube on the valve cover. So, I simply blocked off the fill tube. No biggie.

A few days later I notice that once warmed up my car has this "squealing belts from hell" sound that is not belts, not an accessory, or... and its not idling as smoothly. I was lost and thought it was my throw out bearing, sometimes it would do it sometimes it wouldnt. It got progressively worse though. Then I drove 250 miles to my brothers place, and I was in his driveway, car is idling and squealing away, got the hood up, and for the heck of it while its squealing away, I pull the rubber plug off of the fill tube on the valve cover and you should have heard the vaccum it sucked in!!!! It was like the engine breathed a big sigh of relief: "SSSSSssssuuuuuuu". Squealing immediately stops, and the rough-ish idle smooths out.

If [car running] you unplug the hard line from the oil fill tube, and put your finger on there for a second then let go you'll see it draws vacuum...

Going to have to drill a hole in the new T body to install the metal 90* tube to hook up that hard plastic line and get it working properly.

**Micheal Yount** - Hey, did you ever dyno the difference from stock headers to the aftermarket shorties??? I am still curious if it made a diff on a stock engine? And if so how much HP and TQ??
Thanks.

 

[Michael Yount]

Steve - look at my sig - the engine's not stock. But yeah - I re-dyno'd - we lost 3 HP at peak -- essentially no gain in HP or torque anywhere over the stock headers. All that means is that with my mild build, the stock headers were not a bottleneck to flow.

 

[BlackFox5.0]

Michael, your Tomato can idea seems like a good one...

To my understanding, the oil will drip in from the top of the can, and go and settle at the bottom, while the other hose that comes out the top, doesn't suck in the oil, because it's at the bottom. Am I getting this right? I odn't understand what the speed shop catch can is for though, is it just another "oil trap"?

 

[Michael Yount]

Another oil trap - but on the pcv line -- which I believe on a street car has even more potential to pick up oil and deliver it into the intake as it's being pulled on by vacuum most of the time. Remember, anytime vacuum is pulling on the pcv, air is moving the other way in the line from the valve cover to the throttle body - from the throttle body to the valve cover. No oil can move through that line when the intake's under vacuum because air is moving INTO the valve cover, not out of it. When I've emptied mine, the speed shop can has 5 to 6 times the fluid in it that the other can does, athough both have very small amounts. The cans also pick up condensate.

 

[BlackFox5.0]

I just thought of something... Oil is still coming out of the engine, I don't want to be adding oil to the engine, or draining catch cans. Is there anyway I can keep it in the engine without burning it??

Is this a problem all 302's have?

 

[Michael Yount]

You're thinking about it too much. You're not going to be adding oil if everything's up to snuff. My engine has about 64,000 miles on it and between oil changes the dip stick looks exactly the same at 3 or 4K as it did when I filled it. In my SCCA racer I drained about 8 oz. of oil out of the catch can over 5 seasons - and that was an engine with 145,000 miles on it that spent 95% of its running time between 5500 and 7500 rpm. Just out of curiosity I drained the catch cans in this car about 6 months after they were installed. Virtually nothing came out of the 'tomato' can; maybe an ounce came out of the one connected to the pcv - and most of that was condensate. If your screen and pcv valve are serviced as they should be, then virtually none is gonna be removed from the engine's crankcase. It's not a 'problem' if the engine is in good shape. Most people who have problems with it either let the pcv system fall into disrepair, or they have excessive blow-by (rings/mileage/boost) which over-pressurizes the crankcase.