PCV filter - what does it do...?

Gman2 · 13th June 2012, 21:14

I know this may be a bozo question but what function does the PCV filter actually serve and why does it get caked with gunge

Either way I removed it today and cleaned it up (didn't have a new one) from gunk back to grey fluffy. Took it for a run this afternoon and the car felt more perky - would a clean up make any difference to the response, mpg, overall engine health etc?

Thomas · 13th June 2012, 21:18

Moved to technical help forum

Dragrad · 13th June 2012, 22:42

In short YES

Do a search of the forum, plenty of threads on the subject.

Mike Noc · 14th June 2012, 12:14

Quote:

Originally Posted by Gman2

I know this may be a bozo question but what function does the PCV filter actually serve and why does it get caked with gunge

Not a bozo question at all. The crankcase will pressurise as the engine heats up, along with a build up of combustion gases escaping past the piston rings. If this were unvented there's a risk of oil seals blowing and oil loss.

In the old days this was vented to atmosphere, but nowadays to prevent pollution these gases are fed back into the inlet side of the engine.

That's what the PCV valve does and the filter ensures that only the gases are fed back into the engine.

The diesels don't throttle inlet air, so the inlet is pressurised by the turbo charger, unlike a petrol engine where the inlet pulls a vacuum. That's why you need a separate vacuum pump on the diesels for the brake servo and the EGR.

The gunge is just the byproduct of combustion.

Mike

Gman2 · 14th June 2012, 16:28

Thanks Mike for your very informative response

James.uk · 14th June 2012, 16:52

A diesel will run without a turbo. The pistons downward movement creates suction and draws air in exactly the same an a petrol engine does, but there is no variable air intake opening on a diesel engine, power output is controlled entirely by fuel input - the more fuel you add the faster it goes..

The turbo helps by adding extra air to the mix, and increasing the compression ratio slightly..

In it's basic form, a diesel engine is simple, cheap to run and maintain, and very very very reliable...

...

bramblp · 14th June 2012, 16:57

The PCV relieves pressure in the sump and crankcase that builds up from gasses that escape pass the piston rings from the cylinders. These gasses contain unburnt fuel and other harmfull gasses that cannot be vented to the atmosphere and so the PCV redirects them back to the inlet where they are re-burnt, the purpose of the filter is to prevent oil from passing by.

Gilby · 14th June 2012, 19:39

What does PCV stand for ? (I'm a bit slow here).

Jules · 14th June 2012, 19:49

Quote:

Originally Posted by Gilby

What does PCV stand for ? (I'm a bit slow here).

All the info here

http://www.the75andztclub.co.uk/foru...ad.php?t=68330

Gilby · 14th June 2012, 20:54

thank you.

13th June 2012, 21:14	#1
Gman2 Posted a thing or two ZTT+ 1.8T, mgf 1.8 Join Date: Sep 2007 Location: Warrington Posts: 1,550 Thanks: 28 Thanked 65 Times in 42 Posts	PCV filter - what does it do...? I know this may be a bozo question but what function does the PCV filter actually serve and why does it get caked with gunge Either way I removed it today and cleaned it up (didn't have a new one) from gunk back to grey fluffy. Took it for a run this afternoon and the car felt more perky - would a clean up make any difference to the response, mpg, overall engine health etc?

13th June 2012, 22:42	#3
Dragrad This is my second home *None DROWNED** Join Date: Aug 2007 Location: Cardigan Posts: 33,339 Thanks: 1,257 Thanked 1,664 Times in 1,081 Posts	In short YES Do a search of the forum, plenty of threads on the subject. __________________ Andrew Ich Dien Problem solving is... lateral thinking SEARCH FIRST ...ASK LATER...

14th June 2012, 16:57	#7
bramblp Loves to post Rover 75 CDT Join Date: Dec 2006 Location: Dublin Posts: 470 Thanks: 0 Thanked 8 Times in 7 Posts	The PCV relieves pressure in the sump and crankcase that builds up from gasses that escape pass the piston rings from the cylinders. These gasses contain unburnt fuel and other harmfull gasses that cannot be vented to the atmosphere and so the PCV redirects them back to the inlet where they are re-burnt, the purpose of the filter is to prevent oil from passing by. __________________ [SIGPIC][/SIGPIC]

13th June 2012, 21:18	#2
Thomas This is my second home MG6 1.8T GT SE Join Date: Mar 2009 Location: Falkirk Posts: 9,510 Thanks: 106 Thanked 173 Times in 128 Posts	Moved to technical help forum

14th June 2012, 16:28	#5
Gman2 Posted a thing or two ZTT+ 1.8T, mgf 1.8 Join Date: Sep 2007 Location: Warrington Posts: 1,550 Thanks: 28 Thanked 65 Times in 42 Posts	Thanks Mike for your very informative response

14th June 2012, 16:52	#6
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	A diesel will run without a turbo. The pistons downward movement creates suction and draws air in exactly the same an a petrol engine does, but there is no variable air intake opening on a diesel engine, power output is controlled entirely by fuel input - the more fuel you add the faster it goes.. The turbo helps by adding extra air to the mix, and increasing the compression ratio slightly.. In it's basic form, a diesel engine is simple, cheap to run and maintain, and very very very reliable... ...

14th June 2012, 19:39	#8
Gilby Avid contributor Rover 75 Cdti classic Join Date: Jun 2012 Location: Shropshire Posts: 159 Thanks: 1 Thanked 0 Times in 0 Posts	What does PCV stand for ? (I'm a bit slow here).

14th June 2012, 20:54	#10
Gilby Avid contributor Rover 75 Cdti classic Join Date: Jun 2012 Location: Shropshire Posts: 159 Thanks: 1 Thanked 0 Times in 0 Posts	thank you.