68 NJConv 454

I've been noticing that my driverside valve cover vent has been leaking during driving. Very light drip down the valve cover onto the headers causing smoke.
The vent has a 90 degree fitting that routes the oil vapors to the carb to reburn via a hose.
Do I need a new seal on the vent hole or should I just buy one of those valve cover vent filters and get rid of the hose to the carb?
What causes this? anything to be concerned with?

here is the seal on the driver side valve cover


Should I just get another vent filter like the one on the passenger side (below)?

DRIVESHAFT

If you arent running one, you need a PCV valve.

blckslvr79

PCV Positive Crankcase Ventilation I believe???
The breather side is suppose to be an inlet.
The other side of the engine (sometimes in the intake even) there is a PCV (one way vacuum valve) that is sucking gases out of your engine.

PeteZO6

Agree you need to have a PCV valve. Do you have OEM type four-slat baffles inside the valve cover to separate the oil from the fumes? They are supposed to be the best at stopping oil pull-over.

Just a thought,
Pete

BarryK

agree completely with all the others that you need a PCV valve.
To have the PCV system work properly there are two sides of the system, the intake side which lets in fresh clean air into the motor via a breather vent or a tube from the air cleaner housing and the exhaust side with is the PCV valve which runs to the carb to send the crankcase vapors into the combustion chamber to be burnt off.
Without a complete system like this pressure builds up and causes a lot of blowby oil and can also cause failure of seals from the pressure.

It's best to have the breather vent on the passenger side and the PCV valve on the drivers side. It will actually work reversed from that also but the factory specifically put the PCV valve on the drivers side for a reason.

Here is a post from JohnZ recently from the C1/C2 sectioning explaining why:

"Actually, the PCV valve will be more effective on the driver's side valve cover - it was put there on purpose; the oil that's thrown off the crank and rods goes DOWN on the driver's side (away from the bottom of the oil drainback holes), but on the passenger side that oil is thrown UP (toward the bottom of the oil drainback holes). Putting the valve on the driver's side reduces the amount of oil "pullover" (liquid oil) the valve has to deal with (vs. just the hot oil vapors it's designed to meter)."

blckslvr79

interesting!

BarryK

yes, it was interesting. I had never thought of that before myself but it makes sense. Oil will be splashing in the direction the crankshaft is turning so keeping the PCV on the oil's "low side" makes sense to keep the oil in the motor and only let the vapors out.

68 NJConv 454

Thanks guys for the advice and info. It makes sense now.
However, I do have the PCV valve on the driver side going to the carb and the breather on the passenger side. I just snapped these pics.
I even swisted the PCV valve around and its in there pretty good. What could be causing the leaking? you can even see the residue on the valve cover in the pics.

I don't remember if the Merlin valve covers had the baffles, I know the 454 stock covers did. Something I'll check next time I have them off the engine.

68 NJConv 454

ttt, should i consider putting some silicone gasket around the valve and seal? on the outside of course, don't want that stuff getting inside the valve cover.
????

Durango_Boy

You might pull the grommets out and have a look. They can get old and worn and crack. For the most part when I see oil leaking out from around a PCV valve it's just because the grommet is not sealing well to the valve cover.

bashcraft

Does the grommet fit tight when the PCV valve is pushed in?

7T1vette

Your PCV valve could be gummed up and not functional, too.

lars

No, you don't need any sealant around the PCV. The PCV should be pulling a low pressure on the crankcase, making any leaks at the PCV almost impossible. If there is oil leaking around a snug-fitting PCV grommet, it's from one of 2 causes:

1. Oil baffles under the PCV inside the valve cover are missing or damaged.

2. Ring blowby exceeding PCV capacity.

To test for #2, you can pull the breather out of the opposite valve cover with the engine running and put your hand over the hole. The PCV system should pull a slight low pressure on the crankcase that should suck your hand down to the hole. If there is air puffing up out of the hole instead, you have bad rings or an internal engine problem: do a cylinder leakdown test. If any cylinders are running more than 10% leakage, you have bad rings causing the oil leakage problem.

Durango_Boy

That's really cool. I actually did that once to make sure a PCV system was working and it puffed up at my hand intermittently and the PCV valve was rattling constantly. I just had no idea what the test was proving...now I know.

danno12345

I've got Edelbrock Elite valve covers, and for a baffle, there's a plate about 1/2" below the PCV/Breather hole. If it wasn't there, you could shine a light in the hole & see the rockers.

Just a thought to check for baffles...

Dan

68 NJConv 454

Looks like the oil is leaking under the grommet so I'm thinking the grommet is the culprit. With the PCV valve in the grommet is pretty snug, more snug to the PCV valve then snug to the valve cover, but its not sloppy loose.
The valve itself looks pretty loose inside, like DB said if i shake it it rattles a bit. Maybe I'll blow in it tomorrow and see how much resistance I get.
OH CRAP I hope its not #2, shouldn't be with such low miles on the engine, might be pushing 1k miles on the Merlin crate engine.
The oil baffles are intact. I can see them when I pull out the PCV valve. I'll test for #2 tomorrow morning.
Yup, I see the baffles maybe 1/2 inch below the PCV valve hole.

Thanks guys for the troubleshooting tips. I'll let you know what I discover tomorrow morning...in 6 hours.

68 NJConv 454

OK, ran the engine, pulled the passenger air filter off the valve covers, the suction is faint, barely feel it thru my fingers, but when i put a post-it piece of paper next to it it got vacumed right to the valve cover. NO blow back or air coming out at all.

Process of elimination, next step is a cheap new seal for the PCV valve and passenger side air cleaner.

I also blew thru the PCV valve and it had no restriction, the little valve inside moves freely, you can hear it rattle when shaken.

Theiskell

This is just a thought, but I felt it was worth putting out here for you. I think I read you motor is fairly new. If that is the case have you considered your rings have not seated in yet? I built a 383 over the winter and when I first started it oil was blowing out of the breathers bad when I got on it. I had good suction at idle from the PCV and to say the least I was CONCERNED! Then an old mechanic told me to relax…yea sure. Anyway the blow by continued to get better. Now after about 1200 miles I don’t see the mist around the breather anymore. Just food for thought

PeteZO6

Another thought after re-reading the thread: You have that nice K&N filter on there yet you're pulling your crankcase ventilation air through that little breather on the valve cover. I think you'd be better off if you put a line from inside the air cleaner to the pass. valve cover so you can eliminate that breather. You'll need a spark arrester (like the factory uses) inside the air cleaner, but you will then be pulling really clean air through the crankcase.

Cheers ,
Pete

shafrs3

I had the same seepage problem, concluded it was inadequate baffling in the covers. I ended up building a oil separator out of some scrap tubing, it's loosely packed with stainless-steel wool purchased from a restaurant supply outlet. The PVC valve installs at the top pointing toward the firewall, the unit plugs into the stock grommet via it's base. The wool collects the oil vapor and drains back into the cover, so far it seems to be the fix.

http://webpages.charter.net/ashaffer...s/Breather.jpg