Oil burn cloud on engine deceleration

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I would like to exhaust the PCV path before heading down a different one.

How can I go about figuring out what PCV to try to see if I can find one that won’t pull oil?

I just checked the local parts store and the stock PCV won’t work for me because it has a little nipple on the end that hits the bafflle in the cover.
 
WSUTARD said:
I would like to exhaust the PCV path before heading down a different one.

How can I go about figuring out what PCV to try to see if I can find one that won’t pull oil?

I just checked the local parts store and the stock PCV won’t work for me because it has a little nipple on the end that hits the bafflle in the cover.
Click to expand...

Not sure it is that easy, so to say! You mentioned the car ran well and AFR was good. To me the PCV had to be such the vacuum pulled and metered allows the car to run and idle correctly with good AFR. If the that is met then baffling and catch containers are the items to address. Just a second thought as well is how is the top end being oiled? Is it overdone? I have factory style chrome covers on my 383 and oil method is stock and the baffles are huge!!!!
 
WSUTARD said:
I would like to exhaust the PCV path before heading down a different one.

How can I go about figuring out what PCV to try to see if I can find one that won’t pull oil?

I just checked the local parts store and the stock PCV won’t work for me because it has a little nipple on the end that hits the bafflle in the cover.
Click to expand...


You need the Wagner adjustable PCV. Worth the money.
 
They used to sell push-in and screw-in breathers for Chebbys that had the PCV in the top, and the guts stuffed with a nylon mesh to act as a vapor separator.

I had a PCV problem once. Running a Rally-Cross, with the tranny in 2nd gear,and
the engine at 5000/7000 most of the way, but sawing on the gas pedal. But it went away by itself,afterwards,lol.
I manufactured more and better baffleage and it never happened again. I pump more oil to the top than most guys, so all that aluminum up there gets protection, and for cooling, and for a long engine life;100,000 plus miles now and counting.
If you make your own baffles, you have to provide an escape path for the oil, cuz there will be a ton of it in the mesh; it has to be able to escape.

However, I still agree with all the guys who are pointing to other sources. Consider where the oil is piling up, when going down hill. It normally runs along the head and drains down at the back. Not so when going down hill. It all piles up at the front and if the front valve seals are compromised, it will immediately show up. If enough time goes by, the oil will back up to the pushrod tunnels and escape down into the valley and then down to meet the crank, which will beat the snot out of it, creating a ton of additional windage. Then your whole engine will fill up with that slimey storm, and the PCV was never designed to deal with that.
So, before you drive yourself crazy,messing with the PCV, consider that.
Put the PCV back where it belongs. Time the downhill run until it starts belching smoke and note the vacuum reading in the PCV line. Then run it long enough to empty the muffler. Then repeat the test on flat ground. You may have to begin the test from a higher speed to get the vacuum to come up.
 
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Original SB baffles!

IMG_0252.JPG




This style ain't going to get it done!

IMG_0253.JPG
 
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I agree it's a good idea to check combustion sealing but the OP already said he tried running the car with the PCV unhooked and the oil smoke problem went away... so put me on the list for "install better baffles" lol!

Also what kind of catch can do you have? Not all are created equal, a lot of the cheaper ones still let some oil get by especially if the air is moving fast which is probably the case when the engine is decelerating during higher RPMs...
 
I have these valve covers. And this catch can.

AJ/FormS said:
They used to sell push-in and screw-in breathers for Chebbys that had the PCV in the top, and the guts stuffed with a nylon mesh to act as a vapor separator.

I had a PCV problem once. Running a Rally-Cross, with the tranny in 2nd gear,and
the engine at 5000/7000 most of the way, but sawing on the gas pedal. But it went away by itself,afterwards,lol.
I manufactured more and better baffleage and it never happened again. I pump more oil to the top than most guys, so all that aluminum up there gets protection, and for cooling, and for a long engine life;100,000 plus miles now and counting.
If you make your own baffles, you have to provide an escape path for the oil, cuz there will be a ton of it in the mesh; it has to be able to escape.

However, I still agree with all the guys who are pointing to other sources. Consider where the oil is piling up, when going down hill. It normally runs along the head and drains down at the back. Not so when going down hill. It all piles up at the front and if the front valve seals are compromised, it will immediately show up. If enough time goes by, the oil will back up to the pushrod tunnels and escape down into the valley and then down to meet the crank, which will beat the snot out of it, creating a ton of additional windage. Then your whole engine will fill up with that slimey storm, and the PCV was never designed to deal with that.
So, before you drive yourself crazy,messing with the PCV, consider that.
Put the PCV back where it belongs. Time the downhill run until it starts belching smoke and note the vacuum reading in the PCV line. Then run it long enough to empty the muffler. Then repeat the test on flat ground. You may have to begin the test from a higher speed to get the vacuum to come up.
Click to expand...
Interesting. Ok now I can see why it might be something other than the PCV. If your theory is correct then it would smoke with and without the PCV. I will run the test tomorrow when I have someone who can follow behind me to tell me when it starts to smoke.

For the vacuum numbers I’m guessing I just run a tee off the line going from the PCV to the carb and then run a line to my window so I can watch the gauge?
 
That was the idea, but it may be more elaborate than you need. I think I would just try it at something like 500 to a maybe 800 rpm higher, but in same gear as you were using on the hill. I was also assuming that the hill was sufficiently steep to tip the front of the engine down.
If it's really steep, some old style carbs can slosh fuel into the throttle bores. Also if your T-port sync is open too far the primaries could be pulling gobs of fuel. All that extra fuel, talking theoretical now, would wash the oil off the cylinder walls, and where would it go? You got any bucking going on, down the hill. All that extra fuel would probably manifest as bucking. With a manual trans you would really feel it.If no bucking then forget I mentioned it.
If you wanna try the vacuum gauge, I usually clamp it to the windshield with the wiper blade.
 
AJ/FormS said:
That was the idea, but it may be more elaborate than you need. I think I would just try it at something like 500 to a maybe 800 rpm higher, but in same gear as you were using on the hill. I was also assuming that the hill was sufficiently steep to tip the front of the engine down.
If it's really steep, some old style carbs can slosh fuel into the throttle bores. Also if your T-port sync is open too far the primaries could be pulling gobs of fuel. All that extra fuel, talking theoretical now, would wash the oil off the cylinder walls, and where would it go? You got any bucking going on, down the hill. All that extra fuel would probably manifest as bucking. With a manual trans you would really feel it.If no bucking then forget I mentioned it.
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Never experienced bucking downhill. I have a 4 speed and a Eddy carb.

So tomorrow I am going to do four tests.
1. Downhill with PCV, 2nd gear, 3200
2. Flat with PCV, 2nd gear, 3700
3. Downhill without PCV, 2nd gear, 3200
4. Flat without PCV, 2nd gear, 3700

I will report back my findings.
 
WSUTARD said:
Never experienced bucking downhill. I have a 4 speed and a Eddy carb.

So tomorrow I am going to do four tests.
1. Downhill with PCV, 2nd gear, 3200
2. Flat with PCV, 2nd gear, 3700
3. Downhill without PCV, 2nd gear, 3200
4. Flat without PCV, 2nd gear, 3700

I will report back my findings.
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I realy like it when a plan come together.
The Eddy will be fine as to sloshing. Can't say about the Sync. No bucking means probably OK,then.

I must say tho, that I would find it highly unusual for the PCV to be the culprit at 3200 in second with fully closed throttle; It's just doing it's thing. If it's pulling oil, the something else is putting the oil in there, and the PCV is just proving it.I think all the formerly presented possibilities are still on the table. For me it would be waste of time searching for a different PCV. Just dry this one up with baffling, and find the source of the "blowby".
I guess we'll see soon enough.
 
I have a similar problem with oil consumption and oil out the left pipe during deceleration. Stock 340 w/TQ only has 1500 since build. I am using AMD valve covers. Had block and heads done by machine shop but didn’t do the intake at the time (my mistake). Pulled the stock intake and found 7 head intake galleys wet with oil. Had the intake checked and needed to be machined (found warped). Thought that was the cure…NO.

Once reinstalled, it smoked even worse especially at idle. Closed off the PCV port and breather port; applied vacuum gauge to dipstick tube and found a light positive reading at idle. Today, I removed the PCV and plugged the carb port; the smoke disappeared. May have to run a breather system similar to a marine engine.

Hate to pull it and tear it down again, just may have too.
 
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Just got back from my test and it isn’t good news for me. I had a buddy drive behind me and give me updates as to what he saw.

1. Heavy engine braking downhill causes lots of smoke with or without the PCV. No change in PCV or no PCV in terms of when the smoke starts or how much smoke.

2. Under sustained heavy acceleration there is no smoke.

3. Under normal driving conditions there is no smoke.

4. Under light engine braking on a flat surface there is very small amount of smoke.

Both sides of the exhaust are smoking the same. I do not have a H or X pipe.
 
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I’m going to change the valve seals to see if that fixes the problem. Can anyone recommend the seals to go with? To my knowledge the valves are stock.

Valve Seals
 
WSUTARD said:
I’m going to change the valve seals to see if that fixes the problem. Can anyone recommend the seals to go with? To my knowledge the valves are stock.

Valve Seals
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If the guides are not cut for a positive seal you'll be stuck using an umbrella seal.

Chances are, the guides are bad. A new seal may help for a bit but if the guides are shot it will not help for long.

Bummer.
 
The interesting thing about this is the smoking problem didn’t start till I switched from dual breathers to one breather and a PCV.
 
Different story now arises. Take a deep breath and think it through.
 
1969383S said:
Different story now arises. Take a deep breath and think it through.
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That’s what I have you guys for, to think for me.

Forgot to mention in the OP but was one of the reasons I was 99% certain the oil was being sucked through the PCV.
 
Now that I think about it, how could the smoke be coming from each tail pipe in equal amounts if the oil wasn’t be introduced during the air/fuel mixture? I wouldn’t expect each head to have exactly the same valve seal failure...

If it was bad rings I would be seeing smoke all the time and just out of the side with bad rings.

Where else can oil get into the combustion chamber from?
 
Intake for one! But keep thinking about it and do not rush to conclusions. You have been methodical thus far and stay on that path.
 
1969383S said:
Intake for one! But keep thinking about it and do not rush to conclusions. You have been methodical thus far and stay on that path.
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I guess I don’t understand how the intake can introduce oil. What am I missing?
 
Bad intake gaskets can introduce oil. Is the color of the smoke blue ish?
 
JFLN said:
Bad intake gaskets can introduce oil. Is the color of the smoke blue ish?
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My smoke was from bad cast intake that was not machined prior to installation (warped). I found 7 of 8 head intake galleys wet from oil being sucked in.
My issue is only on the left bank now.
 
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