PCV Crankcase issue
Thread Starter
Joined: Jun 2009
Posts: 10
From: PA
PCV Crankcase issue
Hey guys,
I have a general question here, since I'm learning about this stuff. I want to know what the difference is between an open and closed crankcase. I understand an open uses a PCV valve. But, what are the pros and/or cons to running an engine open or closed? Are engines unique, meaning some are supposed to be closed and some open? If you have an engine that' supposed to be open, can you run it closed, and if so, what are the issues with doing that? How can you tell if an engine is supposed to have an open or closed crankcase? What's affected by the open/closed system? Any info would be greatly appreciated. I'm new to the engine game and just trying to see what's what. Thanks.
I have a general question here, since I'm learning about this stuff. I want to know what the difference is between an open and closed crankcase. I understand an open uses a PCV valve. But, what are the pros and/or cons to running an engine open or closed? Are engines unique, meaning some are supposed to be closed and some open? If you have an engine that' supposed to be open, can you run it closed, and if so, what are the issues with doing that? How can you tell if an engine is supposed to have an open or closed crankcase? What's affected by the open/closed system? Any info would be greatly appreciated. I'm new to the engine game and just trying to see what's what. Thanks.
2nd Gear Member
Joined: Apr 2009
Posts: 446
From: Texas
I've never heard the terms open versus closed when describing PCV systems. I'll assume closed would mean no PCV valve is used and the block is just vented with filters. At least we'll use this for a discussion as a truly "closed" engine will puke a seal due to blowby pressures.
A PCV system uses vacuum to pull the blowby gases out of the block in a regulated manor. Not too much, not too little. A simple filtered system uses crankcase pressure to force blowby gases out. The filtered approach is OK for racing engines with constant oil changes, but not good for long term use as the oil will sludge up faster without the added ventilation a PCV system uses. The PCV system keeps more fresh air in the block.
A PCV system uses vacuum to pull the blowby gases out of the block in a regulated manor. Not too much, not too little. A simple filtered system uses crankcase pressure to force blowby gases out. The filtered approach is OK for racing engines with constant oil changes, but not good for long term use as the oil will sludge up faster without the added ventilation a PCV system uses. The PCV system keeps more fresh air in the block.
6th Gear Member
Joined: Jan 2007
Posts: 5,469
From: AR
I've never heard the terms open versus closed when describing PCV systems. I'll assume closed would mean no PCV valve is used and the block is just vented with filters. At least we'll use this for a discussion as a truly "closed" engine will puke a seal due to blowby pressures.
A PCV system uses vacuum to pull the blowby gases out of the block in a regulated manor. Not too much, not too little. A simple filtered system uses crankcase pressure to force blowby gases out. The filtered approach is OK for racing engines with constant oil changes, but not good for long term use as the oil will sludge up faster without the added ventilation a PCV system uses. The PCV system keeps more fresh air in the block.
A PCV system uses vacuum to pull the blowby gases out of the block in a regulated manor. Not too much, not too little. A simple filtered system uses crankcase pressure to force blowby gases out. The filtered approach is OK for racing engines with constant oil changes, but not good for long term use as the oil will sludge up faster without the added ventilation a PCV system uses. The PCV system keeps more fresh air in the block.
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