Oil dripping from breather tube on fresh rebuild.

Is this theory, or have you seen it happen? I've seen hundreds of blown seals, but ....

A manometer just measures pressure, it won't tell where it's coming from.

 

theory at this point just trying to give him more options but may very well be a scored liner but with the liner it should be blowing out the stack pretty good

 

First try to catch the oil at the blow by tube. A short hose, and a gallon jug will tell. The Turbo could be pumping air in through the drain tube. To check it, you disconnect the drain tube, catch the oil. To check the cold side, take the hose off, see if it’s full of oil. I doubt it, since the air intake hose on compressor was dry, unless it’s all staying in the CAC. And if the seal on the Turbo was blown, probably wouldn’t have any boost. To check the compressor, take the braided line off. Compressor has 2 coolant lines, and 1 oil supply line. The return oil drains into the gear case. That’s how it can cause blowby, adding compressed air into the oil through the return, draining into the gear case. I don’t know if rings were put on upside down. Some of them have a chamfered edge, I think they face upwards. Hard to believe it’s blowing that much from the tube. The top of head/ valve cover would need to be full of oil, not draining, or oil pressure would have to be very high. If that were the case, it would also be bleeding oil from almost every seal.

 

To loose that kinda boost a guy oughta feel it. And to be that kinda oil leak a guy should be able to find it. If you were to look right after stopping the blow by tube should still be dripping or wet. If so well you for sure have a problem. Like @MLC Adventures posted a meter is only gonna measure pressure but not from where. If it’s seal on cold side of turbo what you want to do is block off the air inlet of turbo any way you can. Then pull a 1/4 pipe plug out of intake manifold. Air hose from shop air goes there and pull turbo drain line. Put 15-20 psi of pressure straight into intake and see if you get air out of the turbo drain line. Also the motor itself should hold air if you have a constant air leak from inside motor then your problem is discovered

 

Is there some sort of baffle or something in the valve cover to help keep oil from splashing down the pipe? Its been years since I've been into a Detroit I can't remember.

 

The only other thing that comes to mind is the rocker shafts go on one way. Wrong way will block oil flow, not sure if it would block oil drainage and cause high pressure though. Just a thought. Again, like the Turbo, Compressor, I doubt that’s the problem. New rings are just pushing oil. Might just need to run it. Make sure the oils not going into the coolant. Make sure the new oil coolers not leaking or has a bad o ring seal

 

When the rocker shafts are on upside down on a DDECV it causes low oil pressure the oil just free flows out of the supply passage. Starting it with the cover off removes all doubt what the problem is lol. Round side down for those that are unsure

 

Not a baffle, but a simple wire mesh brillo pad kind of filter

 

I was thinking of the front and rear rockers being mixed up. Not upside down.