Vented oil fill cap mod

[FE 065]

I put this information at the tail end of another post which is drifting onto the back pages, so I'll give it a post of its' own, just in case it's of use to someone.


I modified an OEM oil fill cap to in an attempt to be able to vent to atmosphere without losing oil using a plastic pipe fitting.

You must be registered for see images

The fitting is angled towards 10 o'clock or so as it sits on the valve cover. I run a hose from it upwards from it, behind the intake manifold and high up near the underside of the windshield cowl from the passenger side towards the driver's side and add a small filter on the end of the 2' or so of hose.



Drilling out the center of the OEM fill cap for the plastic fitting also takes with it the inner works that locate the 2 piece cap to its' threaded base. It'll now just spin on the base when put back together, so I cross drilled the underneath of the cap to locate the two pieces of the cap where I wanted them, then ran a long pin through the entire assembly. You can see it sticking out of the bottom of the filler cap.



The hose angles uphill enough from the valve cover to the underneath of the cowl cover (base of the windshield) that any oil coming out of the filler cap should just drain back into the valve cover.



There's a small aluminum box underneath and in the center of the cowl cover, I've secured the hose in its' elevated position by clipping over the top of that box.

 

[99 R/T 10]

I would like to see how it looks mounted up in the engine compartment. Do you have any pictures fitted under the hood?

 

[Streak]

Hmmm...thats a great idea. I would like to hear any negatives to this....

Especially since my baby LOVES to drink oil into the intake on heavy decelerations....putting a catch can instead of putting it back into the intake and this mod should be great on keeping the oil level the same....

 

[FE 065]

Here it is laid out across the top of the engine. All you'd have to do is tuck it under the cowl and support it to keep it elevated.

You must be registered for see images

I used an electrical box nut to hold the plastic fitting in place and a short length of 1/2"ID copper tubing running from inside the plastic fitting to the floor of the oil fill cap to try and provide a direct semi-sealed path.

You must be registered for see images

The 2 pieces of the oil fill cap don't seal to each other, so the cap would weep oil if there wasn't a direct connection between the hole you drill in the bottom of the threaded base and the plastic fitting.



Just an option for those already venting to atmosphere. A PCV system is better for everyday driving, though there's little vacuum at WOT to draw anything out of the crankcase.

 

[Schulmann]

Really good idea to vent the engine.

I have only one question.
Is this engough to vent also the left side of the engine ?

 

[FE 065]

Depends I guess, the entire crankcase should be able to vent through this one outlet at normal speeds. At WOT it probably still could. Though the engine does have to pump it out.




I've read where the advent of PCV systems really cut down on sludge and contaminants in the oil (pan). I think there was also a mention of an increase in bearing life with PCV over venting to atmosphere. If the oil is changed frequently is probably less of a concern.




The more the fitting angle and hose routing is elevated, the greater a path of more resistance there'd be against oil not returning to the engine.




Any higher performance demands might be better addressed with a device to actually **** out crankcase gasses.