Crankcase vacuum vent

sphanna

sphanna

Well-known member
I am thinking of drilling a hole in the intake manifold similar to the vacuum source for the windshield wiper. Then pipe threading a line from there through the valve cover to draw crankcase vapors into intake manifold to be burned. Does this sound like a good idea or is there something I should know better than this? Advise? Yea or Nay?

Steve Hanna

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DON'T do this. the chances are very high to burn motor oil instead of fuel specially with a older engine .
 
I have this in my records;
 

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You would want to fit a PCV valve; just drilling a hole and running a pipe from the valve-chamber / crankcase to the intake would result in a serious vacuum "leak", really compromising performance.

A PCV valve actually allows a small "bleed" during periods of high manifold vacuum ( little load), and opens-up during periods of low intake vacuum, such as hard pulls, when blow-by is likely to be greater.

You really need the PCV Valve.

What is your goal ? Done properly, it would be a general improvement (help scavenge blow-by vapors / moisture from the crankcase, particularly important if your car only sees short local trips, and never gets out for regular runs lasting a 1/2-hour or more. This would be even more true if you are not running a thermostat.

SC Frank
 
Thank you all for your input. SC Frank,I understand now the need for a PCV. I was wondering about that. My intent was to keep my crankcase very clean. I change oil at 500-750 miles and have been a little fanatical about keeping my engine free from sludge and acid from moisture. However I drive it a lot , about 3500 miles a year and mostly on trips of at least 25 miles. So I see that I would not gain much by this. You have all given me reason to forget it. I like to tinker with my coupe and sometimes go overboard. Thank you all for your responces.
 
Steve,

An accessory oil breather tube (available from Brattons, SNyders, and others) that clamps onto the oil fill pipe would probably help as much as anything; in addition to directing blow-by down under the car, the air rushing past the end of the pipe when the car is in motion creates a partial vacuum, thus drawing fumes / air from the crankcase...

Some makers referred to it as the "road-draft tube"...

I am also a big advocate of using a thermostat, or some other means to get the engine temp up to 160-180* quickly, and keep it there.

I just installed a 160* stat ( with two 1/8" bleed holes) in my upper hose, and the car is up to 160* within five-six minutes running, and maintains 160-170*; previously, with the onset of cooler weather (60* ambient air temp). I could drive around town all down and never break 140*... too cold for my comfort.
 
My well worn noise engine doesn't leak a drop of oil. it came with a road draft tube, so I just left it on there. It does it's job just fine.
 
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