Crankcase not venting correctly

Bottom End (crankcases and crankshaft)
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pannick
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Crankcase not venting correctly

#1

Post by pannick »

Sorry guys, I wanted to start a new post because the previous post had 2 different topics. I figured start another one specifically for my current oil venting problem.

History:
I have a newly rebuilt [top & bottom end]1960 Panhead and had recently installed an S&S oil pump. My engine rebuilder installed the pump [per S&S instructions] and also drilled the engine case for the required mod. Meanwhile, I bottomed the primary oiler adjustment screw all the way in to stop oil going to my primary breather tube because I'm running a belt primary. After the following engine idle, I noticed oil weeping from the bottom of the distributor housing. After a few "try this and try that's", I inspected the breather gear timing and all other gears [Checked good], and had inspected the routing of oil lines and any possibilities of blockage or pinching [none present]. After identifying the oil seepage as excessive crank case pressure build up, I talked to a few helpful people on this forum and decided to back out the primary breather oil shut off screw [1 full turn out] and re-route the primary breather to an external vent tube. This helped a lot as I re-started the bike and saw that the oil seepage had stopped; However, I noticed that there wasn't much pressure [about 1-2 psi] coming out of the re-routed primary vent tube. Hmmm...?

Question time:
Q1: Is there supposed to be a lot of pressure venting out of the primary breather or is it supposed to be very light to almost not there?

Q2: After shut down, there was a lot of pressure build up in the oil tank. I understand that there is a vent line going to the tank, but isn't the air venting out of the primary breather tube the engine's first source of venting?

Q3: Why is there so much pressure @ the oil tank, and is this normal?

Q4: How much pressure build up should be @ the oil tank? I believe that there is something like 20-30 psi, maybe 40 I dunno.

Sorry for the huge explanation, but I wanted you all to have the facts.
Thank you for your imput and help in advance!

-PanNick
fourthgear
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#2

Post by fourthgear »

I see that on the instructions for the S&S oil pump ( I down loaded a copy a couple of years ago from there web sight ) it reads " bottom screw two or three times to seat screw " ( primary oil-er adj. screw) ,of course right above it , it reads OVERTIGHTENING screw may cause damage ". But you say you don't have oil coming out , so that's a good thing , its probably seated .

One thing is , how full is your oil tank ? When warm ( engine completely warmed up )does it( oil level ) cover or partially cover up the vent line going back to the motor? That will cause build up in the oil tank. It should be just below the vent line in the tank when fully warmed up .

At idle you will not fell much pressure from that breather , when at speed, it will blow out in accordance with engine RPM. , meaning of course more will blow out , so to speak ,the faster them pistons are going up and down ( just trying to speak in plain terms )the more will air will be displaced from the crank case.That is where the the breather in the gear case comes in .
pannick
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Location: S. California

#3

Post by pannick »

fourthgear,
Yeah, I never went gorilla tight on the set screw, I too saw the note in the instructions about that and was careful not to break it. As far as the oil, it is below the oil tank vent tube, even when warmed up, and is returning oil correctly; I thought that the oil return gear might not have seated correctly or slipped during install but it is.

I'll check the vent line air pressure when throttling and see for an increase.

Thanks for the help.
-PanNick
fourthgear wrote:I see that on the instructions for the S&S oil pump ( I down loaded a copy a couple of years ago from there web sight ) it reads " bottom screw two or three times to seat screw " ( primary oil-er adj. screw) ,of course right above it , it reads OVERTIGHTENING screw may cause damage ". But you say you don't have oil coming out , so that's a good thing , its probably seated .

One thing is , how full is your oil tank ? When warm ( engine completely warmed up )does it( oil level ) cover or partially cover up the vent line going back to the motor? That will cause build up in the oil tank. It should be just below the vent line in the tank when fully warmed up .

At idle you will not fell much pressure from that breather , when at speed, it will blow out in accordance with engine RPM. , meaning of course more will blow out , so to speak ,the faster them pistons are going up and down ( just trying to speak in plain terms )the more will air will be displaced from the crank case.That is where the the breather in the gear case comes in .
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