Why oil leak from breather?

[transbytip]

Wondering why am getting oil dripping from vent in front of pan dosent seem to have a lot of C.C.blow by? It is stock 36 engine that set for many years got it running good now except this oil leak thanks for reply.Cliff.

[Tinker]

Possibly you over filled it with oil, as you said blow-by is not an option.

[Brian]

Is the standpipe, visible with intake manifold off, in place?

[Tinker]

I think he's talking abut the oil pan breather. Or not.

[Brian]

I think he's talking abut the oil pan breather

So am I....thing is if that standpipe is not in place, oil in valley has free drainage down through that pan breather.

[rotorwrench]

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The internal pipe is part of the system for sure. If it is only a few drips at a time, then it may be a blow by situation. Before the breather moved to the pan, the blow by mist & fumes would go out the oil filler/vent and find their way into the cab. Ford evidently had enough complaints that they redesigned the system.


An old engine that has set for a long time will likely have to break back in if there was any corrosion on the cylinder walls or hard crud in the rings keeping them from flexing as they should. Marvel Mystery Oil treatment might be in order.

[Kurt in NJ]

If oil pan gasket for pan without breather is used there will be oil leak path

[Bored&Stroked]

I don't know about you guys, but I've always found a bit of oil misting and occasional drips from the front breather on the pre-49 style engines. These are new engines, with everything possible done to them during the rebuild process - to ensure good quality ring sealing, etc.. I do not run PCV systems/valves on my flatheads - only stock style breathing. I consider it a "standard feature" of the pre-49 style system . . . and just live with it. I've never had a oil pan that stayed "dry" in the front of these earlier style engines.

The system is designed to pull air out this front breather - so even with the correct 'stand pipe' installed, the correct manifold to block baffle installed (which many don't even know exists) and a tight sealing of the ring packs, you'll still get oil vapor/mist coming out the front . . . which has oil mixed in with it. Occasional drips seem to be the norm . . .

[supereal]

Filling more than 4 quarts, unless you have a filter, will often result in oil loss. It is possible the oil level in your engine has reached high enough to contact the crankshaft counterweights. This can result in whipping the oil into a foam which will escape the breath and filler cap.

[Talkwrench]

Hows your breather at the other end .. not blocked up?

[Tinker]

Originally Posted by Bored&Stroked

I don't know about you guys, but I've always found a bit of oil misting and occasional drips from the front breather on the pre-49 style engines. These are new engines, with everything possible done to them during the rebuild process - to ensure good quality ring sealing, etc.. I do not run PCV systems/valves on my flatheads - only stock style breathing. I consider it a "standard feature" of the pre-49 style system . . . and just live with it. I've never had a oil pan that stayed "dry" in the front of these earlier style engines.

The system is designed to pull air out this front breather - so even with the correct 'stand pipe' installed, the correct manifold to block baffle installed (which many don't even know exists) and a tight sealing of the ring packs, you'll still get oil vapor/mist coming out the front . . . which has oil mixed in with it. Occasional drips seem to be the norm . . .

Not to be flippant, but isn't there a reason for a flathead leak, at least to oil the chassis when running down the road? .


oil draft tubes on the 8ba and early yblocks exhausted a bit of oil too. just the nature of the beast. Granted there is a difference in a few drops and a puddle.