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Oil leaking from the dipstick tube??

cldonley

Contributor
Bronco Guru
Joined
Jul 4, 2011
Messages
1,276
Loc.
Robinson, TX
So, finally, the 351 roared to life! Then I had to fix a coolant leak and a sticky throttle, then it roared to life again! But I have an oddity that I’d like your ideas on. While running at a nice smooth idle, I noticed oil smoke coming off the header on the driver‘s side and saw oil dripping from the top of the dipstick tube like it was being forced out. Just a steady drip, one drop every 10-15 seconds. On one valve cover I have a vented cap with no apparent pressure, and on the other I have the PVC which rattles like it’s supposed to and is plumbed to the base of the carb. The vented cap should be plumbed to the air cleaner but is currently open to the atmosphere.

The motor is a 351W roller motor pulled running from a 1995 van. Heads have been re-done. Aftermarket dipstick and tube that puts the top of the tube right between the exhaust ports. Explorer front dress.

Oil pressure with OEM gauge started out around 70 and eventually went down to about 60, at idle, when the engine was warm, and the coolant temp was steady at 185. Running the Motor Craft 2BBL carb.
 

Timmy390

Contributor
Bronco Guru
Joined
Jan 1, 2011
Messages
5,626
Loc.
Conway, AR
How much oil did you put it? Sounds like the dipstick tube is below the oil level. Crank case pressure is forcing oil out. JMO.....

Tim
 
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cldonley

cldonley

Contributor
Bronco Guru
Joined
Jul 4, 2011
Messages
1,276
Loc.
Robinson, TX
How much oil did you put it? Sounds like the dipstick tube is below the oil level. Crank case pressure is forcing oil out. JMO.....
5 quarts. Tube fits in the block. Oil dripping from the top of the tube.
Is the vented cap really vented?
Brand new, wide open to the atmosphere. Pull the cap off, the oil continues to drip.
 

BroncoRebel

Newbie
Joined
Sep 10, 2013
Messages
9
I’d check compression in all cylinders and see if you have any significant blow by at the rings.
Blow by can increase the crank case pressure and spit the oil out of any available vent.
 
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