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Old 08-01-2010, 11:05 PM
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Breather/PVC valve in valve cover

Got a big block 85 468 ci Chevy motor. I have the breather on the passenger valve cover and the PVC valve on the driver side valve cover.

At performed a vacuum idle test and the results was a solid 18 hg and snap throttle is what expected (drop down and back up higher, then stable).

I noticed smoke fumes coming out of the breather. Is that normal? I switched the PVC and the breather positions and now the smoke fumes still came out of the breather.

These smoke fumes oil up my windshield and is difficult to clean.

I was wondering to route the breather via a long hose to a breather bolted underneath the truck. Would that be fine, my thought is fresh air and the smoke fumes would escape away from my front wind shield.

Thanks for your time.

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Old 08-01-2010, 11:26 PM
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are you freaking serious yes its normal for smoky fumes to come out of the breather. that is what the breather does. its there to vent the gasses that slip past the piston rings out of the crankcase. its normally connected via a hase to the aircleaner to reroute the gasses back to be burned. so just take a piece of hose and connect it to the carb or air cleaner that will fix ur dirty windshield
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Old 08-02-2010, 06:51 AM
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When working properly, fresh air should enter the breather and the intake vacuum should pull fumes and smoke (blow-by) through the PCV and re-burn it in the engine.

There are times the PCV valve is closed and some fumes may come out the breather. Often a breather does have a hose going to the air-cleaner so that only filtered air gets into the engine. In the case when the PCV is closed and some fumes may back up into the breather, they get sucked inside and are re-burnt.

So, I'd do these two things:

1/ Check your PCV valve is functioning properly

2/ If it is, add that hsoe you want to the breather, but connect the other end to the bottom side of the air-filter pan instead of way back under the car.

Sidenote: Older engines with a lot of blow-by can create more pressure than the PCV system can handle and you will be stuck with fumes coming out the valve cover breather. Sometimes, when it's bad enough, it can pop the dipstick out. So the hose will help. It is possible a rebuild may be in your future.
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Old 08-02-2010, 07:28 AM
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Yes agress is correct, add a breather to you passenger side cover that has a slip on hose connection, then take the correct type hose (OK for fuel vapor)
and connect it under your air cleaner on the filtered side, you may need to get another cleaner with this hose fitting or braze in your own, under the truck is subject to too much crap. It is important that you run the PVC system especially on a street motor, does you oil stay clean or does it get black on you? the blow by fuel vapors can contaminate your oil if not removed by the PCV system, this can lead to premature engine wear. Remember that when the PVC system is working the clean air is coming into the breather and the bad stuff is being pulled out of the PCV valve and into the carb
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