283 leaky after highway run (long)

[xaircav]

The '62 283 in my '53 3100 will drip a few drops of oil after a run around town but after an extended highway run (75-80 MPH at 2500 RPM) it will leave a puddle about 4" in diameter. The engine has 8000 miles since the rebuild and has always done this. I run a PCV from the road draft tube hole to the carb and an intake with a fill tube and breather. The factory vapor can in the lifter valley is in place. My theory is that at highway speed when vacuum is low pressure builds in the crankcase and pushes oil out the rear main seal. I've ordered a road draft tube and mounting kit and will report the results. I'll bet the pic is upside down.

[xaircav]

Told you so. Carb is an Edelbrock 500CFM, intake is an Edelbrock EPS, cam is a mild 204/214. It will use less than a quart between changes and never smokes but the garage floor in my new house looks like the Exxon Valdez parked in there.

[dwcsr]

one of three things make it leak at the rear seal area, The rope seal was not installed correctly, most likely, the pan gasket rubber seal is not seated properly. or its running from the back of the valve covers to that area, One other may be one of the plugs in the back of the motor are weeping but not likely

with that breather you can't build enough pressure to push oil out past a good seal

[72Mountaineer]

Do something to keep your floor clean...go to the dollar store and get a cookie sheet or pizza pan. First thing is easy.

[xaircav]

Originally Posted by dwcsr

one of three things make it leak at the rear seal area, The rope seal was not installed correctly, most likely, the pan gasket rubber seal is not seated properly. or its running from the back of the valve covers to that area, One other may be one of the plugs in the back of the motor are weeping but not likely

with that breather you can't build enough pressure to push oil out past a good seal

I used a neoprene rear main seal and the $50 buck Fel-Pro valve cover gaskets with the metal core. The heads stay dry as does the intake ends where I used RTV instead of the gaskets. I wished I had used the one piece oil pan gasket. The road tube is ordered and paid for. I it doesn't work I'll live with the drip.

[dwcsr]

Originally Posted by xaircav

I used a neoprene rear main seal and the $50 buck Fel-Pro valve cover gaskets with the metal core. The heads stay dry as does the intake ends where I used RTV instead of the gaskets. I wished I had used the one piece oil pan gasket. The road tube is ordered and paid for. I it doesn't work I'll live with the drip.

If its neoprene then it may have been put in backwards lip toward the flywheel. Did you seal the ends of it. Also on the replacement for neoprene you should install them off set at 2 & 8 o'clock so they don't have a part line with the cap part line. It can be a pia to do but it works. The old blocks were known to leak at the part line as well. Could it be trans oil and not motor oil?

[xaircav]

Originally Posted by dwcsr

If its neoprene then it may have been put in backwards lip toward the flywheel. Did you seal the ends of it. Also on the replacement for neoprene you should install them off set at 2 & 8 o'clock so they don't have a part line with the cap part line. It can be a pia to do but it works. The old blocks were known to leak at the part line as well. Could it be trans oil and not motor oil?

I had Dave Vizard's book by my side when I assembled it. I'm confident the seal is in the right direction, offset from the main cap and a dab of RTV at the joint. Trans is a manual full of 75W90. It's definitely motor oil. Let's table this discussion until I try the road draft tube. Watch for a report.

[nvrdone]

my 327 liked to mark its territory after a long drive & I chased that oil leak for a long time. finally added some uv dye to the oil & found the oil was dripping out of the back corner of the right valve cover. replaced the gasket many times & still had a leak. finally took a center punch & punched a series of dimples in the head where the gasket fits.
for some reason that solved the problem. good luck

[xaircav]

Originally Posted by nvrdone

my 327 liked to mark its territory after a long drive & I chased that oil leak for a long time. finally added some uv dye to the oil & found the oil was dripping out of the back corner of the right valve cover. replaced the gasket many times & still had a leak. finally took a center punch & punched a series of dimples in the head where the gasket fits.
for some reason that solved the problem. good luck

I think I solved the valve cover leaks I used to have with the high dollar Fel-Pro gaskets. My oil drips out the hole in the dust cover.

[mr48chev]

Well I'd think that the road draft tube thing is a bad idea as most likely you will end up with a bigger leak somewhere. That said, what the guys said above is pretty well it. Those engines were never known for being leak proof from day one and it isn't uncommon for one to blow a bit of oil out where you don't want it coming out on a hard run.

It's one of those things that you just have to keep after and knock off one little leak at a time.

[AnotherWs6]

What is a road draft tube?

[xaircav]

Originally Posted by AnotherWs6

What is a road draft tube?

You gotta be under 40

[xaircav]

Originally Posted by xaircav

You gotta be under 40

I'm glad you guys provided a comprehensive answer to AnotherWs6 question. My curt reply was an attempt at humor but may have been perceived as rude.

[_Ogre]

(over) 50

[Coupeguy2001]

Years and years ago, the car manufacturers installed solid rocker covers, and to vent the engines, they installed a vent pipe somewhere on the engine. In 1963, the Feds required the engines made after 1962 to burn their own vent vapors. The road draft tubes were gone, and the PCV valves came into use. When the engine was not making vacuum, such as on acceleration, the new style rocker covers had a breather pipe to the air filter so the vapors still got burned. The road draft tube is the original engine vent.
You know an old car has one, because if it does, it is a stinky hydrocarbon smell floating around the car when it is at idle.
If it has a PCV valve, you cannot smell anything around the car except the exhaust.

PCV is abbreviation for positive crankcase ventilation. When the engine is idling, or steady throttle, the manifold vacuum is the highest, and the pcv valve is allowing the engine vapors to be vented to the manifold somewhere, where they are distributed to the cylinders.

[dsraven]

a road draft tube is a metal pipe, like muffler pipe, that connects to a vent hole in the block near the distributor area and runs down and exits near the rear of the engine but below the oil pan, height wise. it allows a aventuri effect, from outside air passing the tube when the vehicle is moving, to draw engine fumes out of the engine and away from underhood. sometimes these tubes will also drip a bit of oil. the engine usually had a oil fill tube, in the front of the intake manifold, with a breather/filter style cap on top. this allowed a flow of filtered air through the engine. by filtered I mean steel wool inside the cap. the system was replaced with a pcv system which uses engine vacuum to draw fumes from the engine through a metered orifice. that system used a pcv valve in the one valve cover and a course filter was placed in the other valve cover oil filler cap. later the course filter was placed in the engine air filter housing an accounted for oil build up in the housing on high mile engines with lots of blow by. a pcv valve with a larger orifice was used to compensate some for older engines.
a lot of diesel truck engines used the road tube until not that many years ago.
anybody, correct me if I am wrong here.

[mr48chev]

I think you nailed it perfectly DSRaven. One of the best descriptions I've seen.

Get a bit of blow by with a draft tube and you sit in a cloud of oil smoke at every stop light too.

[AnotherWs6]

Not at all. Yes, I am under 40. Not by much any more unfortunately.

[xaircav]

Originally Posted by xaircav

The '62 283 in my '53 3100 will drip a few drops of oil after a run around town but after an extended highway run (75-80 MPH at 2500 RPM) it will leave a puddle about 4" in diameter. The engine has 8000 miles since the rebuild and has always done this. I run a PCV from the road draft tube hole to the carb and an intake with a fill tube and breather. The factory vapor can in the lifter valley is in place. My theory is that at highway speed when vacuum is low pressure builds in the crankcase and pushes oil out the rear main seal. I've ordered a road draft tube and mounting kit and will report the results. I'll bet the pic is upside down.

I installed the road draft tube and removed the PCV and the oil drips are greatly diminished after an extended hi way run. I think my theory in the original post was correct. At idle I see just a wisp of blow by coming out of the tube and ventilated oil fill cap. Will one of the more computer literate flip my pic over please?