Frankie the Fink

Some of you may recall my post last month about a large, white cloud of smoke (and the smell of fresh oil) coming out the rear passenger side of my car when I let off the gas after 'hammering the car' in 4th gear above 60mph. My inital thought was I over-filled the oil after a change...it was over the high mark on the dispstick maybe 1/4 of a quart. (This only happened one time pretty close on the heels of the oil change). I have not been able to make the car generate even a puff of smoke since that incident!

Had the car out today and got a little aggressive and when I park the car I find a puddle 2-3 tablespoons of fresh oil under the car.

Put it up on ramps and there is oil coating the passenger side exhaust, the tranny crossmember and right side of the frame....I wipe it all off, start the car and rev it up real good....not a drop of anything anywhere, let it sit for 2 hours and still nothing. Run my finger up the draft tube and there is fresh motor oil all around inside. The oil level is about 1/8" BELOW the high mark now on the dipstick - and the oil pressure is over 60PSI at higher RPMs (the guage pegs so I don't know how high it gets but my dyno run shows 64.7PSI at 5,500RPM.

Is there any condition that would cause fresh oil to run out the draft tube ? I doubt the crankcase is getting pressurized...there are no radical hills and switchbacks in Central Florida of course. Could it just splash out at high RPMs? This one has me going ...

Its a stock 283ci with only about 4,000 miles since being rebuilt in '04 and runs real strong.

midyearvette

do you have the "tomato can" installed in side the intake manifold??..that should keep raw oil out of the tube and just allow fumes to get by....does that tube exit the pass side??

GCD1962

If the oil baffle is installed underneath the manifold, then it probably is excess pressure forcing it past the baffle. Is your only other "breather" the oil file tube?

MikeM

It's not abnormal for road draft tubes to condense oil vapor inside the tube and eventually drip some oil out.

If you're old enough, you should be able to remember the concrete roads that had the stain down the middle of the lane from drippy road draft tubes.

prestige6

Wrap an old cotton sock around the end of the draft tube to catch all the residue but change it regulary..It will keep it off your frame and other componets..

67L36Driver

Early '50s Oldmobiles had a filter can on the end of the road draft tube. Better than an old sock.

Frankie the Fink

You guys are TOO fast:
midyearvette:
I have the tomato can in the lifter galley and the road draft tube extends downwards on the passenger side....
gcd1962:
As far as I know, the breather tube is the only vent to atmosphere (no PCV valve or rebreather system)
mikem:
I do remember in motorcycle class years ago being told to not ride in the center of the lane because of the 'oil slick'....its a little unnerving to see the occasional small puddle under the car and, worse, the rare smoke cloud though (oil on the exhaust pipe I'm assuming).
prestige6:
My word, man...are you telling me I need a road draft tube condom ???
Interesting idea and I may actually consider that.

ALL:
Without starting another thread on the whole topic....is there any way changing from the canister oil filter to the spin-on adapter with a regular oil filter could cause this ??

midyearvette

changing to a spin on filter will not cause any more or less blow by....im no expert on c1's or anything else for that matter but fredano are you saying the draft tube is the ONLY vent for your crankcase?? i thought the fill tube had a vented cap.....btw mikey is correct on saying the draft tubes dripped oil with vapors but i am assuming you think you have too much raw oil coming out.....have you done a cylinder leak test??..good luck

Frankie the Fink

The fill tube does have a vented cap...and I would expect to have some issues with the dipstick if the crankcase were getting pressurized so I don't think that's it now. Really thinking I'm getting some 'splash over' from the lifter valley somehow...all respect to MikeM but this seems to be more than oil vapor condensing and it happens too irregularly for that it seems.

Haven't done a leak down test but this car blows NO smoke 99.9% of the time....even had forum member wmf62 follow me while I 'dogged' the car and not a whiff of anything. If it were blowby I would expect more apparent symptoms..

Is the 'tomato can' directly connected to the hole where the road draft tube enters the engine ?

midyearvette

yes. the can is a push fit into a hole in the rear of the block and is secured by a single bolt that threads into the top of the valley....going from memory of about 50 years ago, if you delete the can, then the open hole is exposed to too much oil....have you thought about plugging the tube and relying only on the fill tube breather for awhile just for a test??

1snake

I'm not sure about 61's but in 1960, all solid lifter motors used non-vented caps therefore the only venting of the crankcase was through the road draft tube.

Jim

I just checked, 61's are non-vented as well (solid lifter cars). It could be possible that the vent canister under the intake came loose and fell out of its hole.

rustylugnuts

Why don't you replace that draft tube with the Calf PCV, it will solve your problems instantly?

rustylugnuts

1snake

Unless his canister is loose or he has some other mechanical problem. That "band-aid fix" would only mask the problem instead of solve it.

Jim

rustylugnuts

It's not a band-aid, it's a factory resolved option for that year Corvette!

rustylugnuts

Frankie the Fink

The plot thickens...(seems Jim is right - as usual).

These are pics of my oil filter cap (doesn't look vented to me). The sticker saying to clean and re-oil it is something I added on (incorrectly it seems). The 'tomato can' was on there when I replaced the intake manifold gaskets but I didn't check anything else about it....I don't know if its come loose or not..(I don't want to think about taking the intake manifold off again.)

The PCV systems I've always seen have an air intake (through oil filler cap usually) in addition the 'venting' of the PCV....so the road draft is the both the 'inny' and the 'outty' on my engine ??! Corv Central has both vented and NON-vented oil filler caps for the '61...WTFO ?

What is the calf PCV ?

1snake

No motor should have the amount of oil coming out of the road draft tube as Frank is having (which started suddenly). Something changed in his motor and needs to be rectified not masked.

Jim

rustylugnuts

What engine do you have? I will look up all the information for you, give me some time....pizza's getting cold!

rustylugnuts

1snake

Frank, That is the correct (non-vented) cap. The other style (open) cap has the sticker. I think the first thing I would do is the pull the road draft tube and using a coat hanger in the hole, see if the canister is still there. If you can push the coat hanger in without hitting something solid, there's your problem.

Jim

Frankie the Fink

rusty:
The motor is the 270HP 283ci original, solid lifter 1961 motor with dual quads...rebuilt in 2004 with only a few thousand miles on it. A Duntov 097 replica cam was installed .. engine runs strong (real strong) with no smoke (normally) or bad sounds..
jim:
That was the very troubleshooting idea I had but didn't know if it was a 'straight shot' from thd draft tube engine hole straight to the oil baffle. Guess that's what I'll try ...after the holiday weekend gets done.

Is there any downside to running a vented oil filler cap for a while just to see if it helps ???

GCD1962

I would pop on a vented cap to see if that relieves the pressure - it's the cheapest way to go at first. It's also possible that the canister under the manifold go crunched at some point in time - a very common way to get clearance when using an aftermarket manifold. You said you didn't think it happens until high RPM which seems to indicate that it is only at that point that the pressure builds too much and then wants out through the road draft tube. Giving a little more escape through a vented cap might just solve it. (you can propably still get a generic GM chev cap at an autoparts store,)