My rebuilt SBC 350 engine has about 1500 miles on it and I am noticing that oil is coming out of the base of the dipstick and the base of the distributor. My oil pressure reads about 78 when started and then drops down to about 65 when warm ( seems high to me). I put a brand new PCV valve and breather in the valve covers. PCV connected to large port on Q-Jet.
I started her up and pulled the breather out to see if it sucked my hand at all. It did not. Then I watched the hole (with the breather out) , as it got hot, I could see faint plumes of smoke coming out of the hole.
When I first drove the car I did many uphill runs with the gear down low in the rpm range - then floored it to put a lot of force on the motor.

Can all of this be normal behavior on a newly rebuilt motor - until the rings are better seated? Or is a leakdown test in order?

thanks

 

I had a thread (355 Still Leaking Need Help) there was a lot of discussion about this specifically "Blow By" you might want to check that out. At first I thought I had blow by casuing my pan to fail to seal as I had a leaky oil pan. Found out through discussion that I forgot to plug the top bolt hole by the fuel pump casuing the leak. My rings seated and all is ok "knock on wood"

On to your issue...smoke coming out of the breather hole is a tell tale sign of "Blow by" honestly and I hate to say it but it doesent really get any clearer that that.

Did you ever have issues starting the engine or did it ever run as if it was flooded? Did you ever have issues with the carb and the choke getting stuck causing more fuel flow than normal. I ask this because if you did that and had excessive fuel flow it could cause the rings to not seat it dosent take long with a new engine.

Hope you get it figured out.....bet your a$$ that I would have this engine back to the builder ASAP and no this is not normal behavior on a new engine.

 

Darn, I have had the PCV valve connected to a port (Top) on the Q-Jet but it wasn't sucking when I pulled it out and felt the bottom of it. I changed to another port on the Q-Jet (at the base) and now the PCV is sucking well now. Unfortunately I can't say the same for the breather hole. I took it out but still didn't feel suction with my hand.

 

If you don't see fumes now and the PCV is pulling air as it should I would watch the oil level and finish breaking the motor in.

 

You should have a O ring on your dipstick tube that should stop the leak. Or maybe a little Permatex around the fitting into the block.
You should also have a gasket at the base of the distributor. Sometimes you have to double these up if your distributor sits too high above the manifold.
If you are getting vacuum at the carb, but not at the pcv valve, then you have a collasped hose or bad pcv valve. Then you should suck air throught the engine from the breather on the other valve cover. A little vapor/fumes/smoke is normal. That is why the system is there, to pull the vapors/fumes out of the crankcase.
Your rings are seated as much as they are going to get at 1500 mi, but it doesn't sound to me like you are getting alot of blow by, so nothing to worry about.
If your oil pressure gage is correct, your pressure is WAY too high.

 

65psi is not to high .. And both leaks sound seal related . On the PVC get a heavy hose that will not restrict the flow.

 

My problem with the PCV was that the large port near the top of the Q-Jet doesn't suck air. Shouldn't it?

 

There is only one port on Q-jet that allows a 3/8" hose to be attached directly to it that can be connected to your PCV....and it is located on the baseplate of the carb in the front.

If you have good vacuum on the PCV when you pull it out of your valve cover and your finger can get sucked to it. This is good. Then ..when the engine is running...while holding onto a dollar bill...place it over the opening in the other valve cover where your fresh air tube grommet is located and see if the dollar bill gets sucked to the grommet. If it does...and you can feel drag in the dollar bill when you try to slide it off....you are fine. If it does not get sucked to it...you have a vacuum leak somewhere causing un-filtered air being pulled into the engine....which is BAD...obviously.

AS stated in a previous post...if you feel air or the dollar bill blows away from the grommet while the engine is running...this is really not good...especially if the PCV is installed.

Like mentioned...oil dipstick can be allowing air to get sucked into it...front and rear seals on the intake allowing air to get sucked in ...no gasket on the oil fill cap in the valve cover.

DUB

 

Top rear port does not matter in this scenario....if that is what you are referring to. It is used but NOT a part of the PCV directly...and the port is about 1/4" and not 3/8".

DUB

 

On my 70 q-jet, the pcv is connected to the port on the front bottom of the carb. About the same size as the pcv valve. Not sure what port you have on the top.
Is this 65 at idle? What is it at higher rpm? 65 at idle is overkill and is higher than most people would recommend for a street engine. Probably won't cause a problem, but not what you would generally shoot for--unless your pop the oil line to your gage and spray your interior. If you ever have the pan off I would change the spring in the oil pump and drop the pressure. This oil pressure is not causing your leaks.

 

First off, your PVC needs to be connected to MANIFOLD vacuum, not PORTED vacuum. I don't care what anyone else says, if your PVC is connected to a ported vacuum source it simply wont work correctly. Period. The ONLY time your PVC is receiving a signal is when the throttle blades are open, and even then the ONLY time you'll receive full vacuum is WOT, and even that will be brief under load. If the carb doesn't have a direct manifold vacuum source, find a 3/8" connection on the intake manifold or create one. Once that is ironed out, if you still exhibit shades of blue from your exhaust, and it's a true dual exhaust, take the side smoking and pull the plugs. If you have a ring not seated, broken, ect., that plug will look like crap. Good luck!

 

Huh?

 

I don't have any shades of blue out the exhaust. The breather hole should suck when I take the breather out. The PCV is sucking strong now but the breather hole - not at all.

 

No shades of blue is good.
Mental note:Hints of blue under acceleration indicate rings (blow by). This is gases under combustion that seep through the rings into the crankcase area. This causes a positive pressure in the entire crankcase all the way up to the valve covers. It's this "pressure" that causes the blow by in the crankcase, out the dipstick, oil fill cap or wherever is finds the least resistance to escape. One way or another it WILL find a way to escape. This should clear up the rings. Onto the other side of the coin. The valves.
If you wind her up going down the road (at least 5000 rpm), let off the gas and let her idle down in gear on her own to say 1500 rpm, then hit the gas...you see blue then, it's valve seals or valve guides. The cylinder under deceleration will create a low pressure area and literally suck oil through the valve guides into the cylinder to be burned and spit out in a blue kind of way.

All this said, a dicky-dood PVC system can cause the issue your speaking of...

 

First off, your PVC needs to be connected to MANIFOLD vacuum, not PORTED vacuum. Correct!
The ONLY time your PVC is receiving a signal is when the throttle blades are open - NO
and even then the ONLY time you'll receive full vacuum is WOT - NO.

THe PCV valve is just that, a control valve. Full manifold vacuum at idle pulls the valve into it's restrictive mode which allows a small amount of metered air to be pulled into the intake to purge the crankcase (so you should feel a bit of suction on the bottom of the valve at idle). If there is absolutely no vacuum on the bottom of the valve at idle, either the valve or the hose to the carb are plugged.
There is almost no vacuum at WOT, so the spring in the valve opens it more to let larger amounts of (normal) blowby into the engine.

 

That port is probably the fuel bowl vent. I believe it should be connected to your charcoal canister.

Scott

 

Then there must be an opening in the crankcase area that is allowing air to be sucked in at...thus making the breather hole grommet area not able to suck in air.

Like written earlier...the intake front and rear seal areas can be open allowing air in...but also would allow oil to leak out, oil dipstick, oil filler cap seal, valve covers, oil pan, front timing chain cover, distributor seal.

OR...you actually have compression seeping past the rings and it is so great that the PCV can barely keep up with it....or your valve guides and seals are also gone...but this would produce a blue smoke issue...which you say you do not have...so I doubt that the valve guides and seals are the issue.

I have had to perform a compression test and then a leak down check to find issues with an engine in the past. I know it is a new engine...bit still...if it came into my shop...I would perform this these tests.

OR...I might try this first...
Once I measured the vacuum at the PCV so I know what to set my vacuum pump to...so if when the engine is running I was getting 20 inches of Hg(for example). Then I would regulate my vacuum pump to the exact same thing. Then I would connect my vacuum pump to the PCV and begin trying to find where the unwanted air can be coming in at without having to have the engine running. Then I would go over and check and see if the breather hole will allow paper to suck to it....and hopefully it really pulling air very hard through the grommet and holding the paper really tight . If it does...then this would make us deduce that there is/are no seals leaking because it is sucking the paper to it...and that there is an issue in the rings...because these rings would be the culprit...thus allowing compression pressures to seep past the rings and enter the crankcase.

DUB

 

Top front left side and angling downwards towards the left valve cover is the bowl vent.

DUB