TedH

This morning, I put the C3 up on jack stands and started draining the engine oil in prep for replacement of the Fel-Pro one-piece oil pan seal. Have set out to replace the seal as I have what appears to be either damage to the one-piece seal (after repeated removals) OR a rear main seal.

However, as I popped the hood, I saw something peculiar... engine oil on the intake immediately below the heavy hose that runs from the PCV to the lower vacuum inlet on the carb base. Stranger still, I found A LOT more oil in that same spot last week and ignored it (I think now that I should not have). So, I replaced the hoses that were hardened around the PCV and installed a softer grommet where the PCV goes into the valve cover as it was easy for me to just pop the PCV out of the grommet.

Something strange I also found was engine oil running down the lower radiator hose... from the PCV (I assume).

So, after having drained my 4 quarts of 5W-30 and about to start loosening the oil pan bolts to drop the pan and replace the pan seal...

I asked myself: "Self, if I were a top-side oil leak, would I look like a pan seal leak after 2-3 hours of driving...?"

I can easily button the few bolts I have removed and put some fresh oil in. I'd just as soon NOT have to drop the pan as I was also going to remove the starter and trans shield to get at the rear bolts on the pan.

Shall I put fresh oil in. button things up and monitor the situation further?

TimAT

PCV in the left rocker cover? I can't see how oil from that would get to the right side and run down the lower radiator hose. Oil there, I'd be looking around the fuel pump and the right side rocker cover.

If your rocker covers don't have a baffle under the PCV it can suck up a bunch of oil, but it will go into the intake and be burned in the cylinders.
I'm thinking you need to do a lot of cleaning, after you replace the bolts that have been removed and install fresh oil. Then have a nice afternoon drive followed by a re-inspection.

TedH

Good advice. I will check the fuel pump seal at the block and front engine area too as that could be contributing to that oil at back of engine.

I am thinking maybe, just maybe, there was enough oil to drip off of the intake onto one of the legs of the water pump and onto the radiator hose. There was not a lot there below the lower radiator hose but maybe 1-2 drips. The bulk of the oil could have made its way to the rear of the engine. With the engine slightly tilted (at least it looks that way) toward the rear of the car, I figured the oil is/was running either down the rails of the valve covers or along the edges of the intake. The hoses at PCV were definitely hardened and I had no clamps on them. Have since clamped and added new hoses.

I'll take your advice. Will clean it really good also. I may have a little in the trans splash pan. I will bring the fresh oil to the dipstick mark and take it for a few rides. If the dripping subsides (what is left to drip), I will know it is solved. Otherwise, I will give it all a closer look and possibly proceed with the oil pan seal.

Correct. PCV is in the left front corner (stock location) of the driver's valve cover. It has a baffle in both that location as well as where the PCV line runs into the air cleaner from the right rear of the passenger side cover.

Question: these are stock height valve covers. Could the 'fat' Comp Ultra Pro Magnum rockers be too close to the baffles? I do have taller chevy valve covers in a box on the shelf but they cause a problem being too close to the alternator (I would have to run a longer alternator belt).

TedH

In addition, I do get some blue smoke while the engine is running. Not a lot but if oil is making its way into the base of the carb via PCV hose, then I would expect to see some blue in the exhaust (smoke).

TimAT

If the rockers are hitting the baffles, you'd hear it. Noise. Big time.
A little blue smoke could be oil getting past the rings or valve guides. A compression and leak down test, along with taking a close look at the spark plugs could help pinpoint that.

From what you've said, I still think that washing the engine down top to bottom so that you know there's no oil hanging around will be the place to start. Maybe some Simple Green or the like and lots of water.

7T1vette

If your valve cover is not baffled below the port where the PCV valve fits, oil splash will be sucked directly up that hose. And, if that hose doesn't seal really well, it will drip out onto the intake.

TedH

Yes. both covers have baffles. I confirmed the drip at radiator is antifreeze; when it felt oily, I thought oil. Closer inspection, radiator fluid. There is no more leaking at the PCV onto the intake/valve cover.

I appear to still have some drip at rear of engine. I am going to pull/inspect the vavle cover gaskets just in case one is not properly positioned on cylinder head. Also going to inspect rear of engine and front of trans as engine is running to see if I can see the source of the leak. Then, going to pull the pan gasket. Passenger header/starter have to come out to get at fasteners.

1977L48

also look at the back of your intake/ dizzy gasket/ oil pressure sending unit if its on the back of the block. ive seen people tear into and replace a rear main seal thinking it was bad only to find out it was one of those I mentioned.

427V8

Are those factory valve covers?
Aftermarkets almost never have enough baffling, you'd be surprised at how much oil is flying around in there at RPM.
you need really good baffling to keep oil out of the PCV system.

TedH

The valve covers are stamped steel, aftermarket (chromed). Stock height and the baffles are the same dimensions and appearance as OEM. I would try stuffing material into the baffle housing if I could be assured it would not end up in the bearings/engine.

I will also check out the valve cover gaskets, sending unit and rear of intake before I drop the pan. Last weekend, filled and checked after clearing up the PCV oil on intake and it still dripped for about half hour after running.