MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: Janner_Sy on October 02, 2009, 07:26:21 pm

Title: problems a broken PCV can cause.
Post by: Janner_Sy on October 02, 2009, 07:26:21 pm
Well i finally put my BSH PCV catch can on my car this afternoon, after a week of postponing it.

and what I have noticed immediately on the first test drive(although it could be me imagining things) is that when accelerating my wheels are spining up much easier than before it was fitted, and it feels a little bit morte eager and responsive. and whilst driving normally it is noticably more economical than before by about 2mpg.

So i was thinking maybe it was fooked before I swapped it and now my car is producing the correct power/torque.

I know the PCV is a known weak point of the TFSI engine, but what are the consequences nof a PCV breaking?

lack of power, bad fuel economy maybe. or is it just me :ashamed:
Title: Re: problems a broken PCV can cause.
Post by: bacillus on October 02, 2009, 07:31:22 pm
A bad pcv can lead to loss of some boost, decreased mpg and, if complete failure, oil blowing out through your oil cap.
Title: Re: problems a broken PCV can cause.
Post by: Janner_Sy on October 02, 2009, 07:40:59 pm
cool. I hope thats the case, and my PCV was gone and is now working as it should be. as i had previously thought there was an issue with my car before
Title: Re: problems a broken PCV can cause.
Post by: gazbutS3 on October 02, 2009, 07:46:37 pm
I noticed a deffinate improvement too Simon, it is much crisper down the bottom end. I'm pretty sure the PCV was leaking/weeping as there was a tell tale oil smear/stain from the bottom of the OE item :smiley:

I mentioned the weep on here after the fitting but not the crispness as I was putting it down to placebo and thought everybody else would :smiley:
Title: Re: problems a broken PCV can cause.
Post by: Janner_Sy on October 02, 2009, 07:48:27 pm
i initially thought it was a placebo effect and the responsiveness could be, but the traction control was flashing abit, and i dont normally notice it
Title: Re: problems a broken PCV can cause.
Post by: BMX on October 03, 2009, 01:14:36 pm
mine used to blow oil out of the cap, not much though, the mpg was 28 and after a week its reading 30 all the time
Title: Re: problems a broken PCV can cause.
Post by: Bazgti on March 14, 2012, 07:38:58 am
A bad pcv can lead to loss of some boost, decreased mpg and, if complete failure, oil blowing out through your oil cap.

Sorry to drag an old post back into the limelight. But what is ment by 'oil blowing through the oil cap?'

Title: Re: problems a broken PCV can cause.
Post by: bacillus on March 14, 2012, 08:12:24 am
Sorry to drag an old post back into the limelight. But what is ment by 'oil blowing through the oil cap?'

Exactly what it says.
High pressure builds up in the system and if it becomes high enougn then it vents by breaking the seal the oil cap has with the engine rocker cover.
Title: Re: problems a broken PCV can cause.
Post by: smokey on March 14, 2012, 08:30:58 am
Hey guys

Do TDI's have this too?
Title: Re: problems a broken PCV can cause.
Post by: Bazgti on March 14, 2012, 09:15:39 am
Sorry to drag an old post back into the limelight. But what is ment by 'oil blowing through the oil cap?'

Exactly what it says.
High pressure builds up in the system and if it becomes high enougn then it vents by breaking the seal the oil cap has with the engine rocker cover.

So it pops the top of the cap off? Where the writing and oil symbol are? I think mine has done this. What does the high pressure imply?
Title: Re: problems a broken PCV can cause.
Post by: fab5freddy on March 14, 2012, 09:22:32 am
^^^ the high pressure implies that your PVC is broken and is not venting as it should
Title: Re: problems a broken PCV can cause.
Post by: Bazgti on March 14, 2012, 09:37:29 am
Ahhhhh... Well i changed that yesterday n the cars boosting a touch better but is still flat and the boost is intermittent. You think the extra pressure build up could have split a pipe? My Anni was a bugger for splittin em.
Title: Re: problems a broken PCV can cause.
Post by: fab5freddy on March 14, 2012, 10:42:44 am
Have you checked the DV?

Could be the source of your boost problem
Title: Re: problems a broken PCV can cause.
Post by: Bazgti on March 14, 2012, 12:28:43 pm
Yeeeah... Awesome fitted a piston type for me a few months ago.
Title: Re: problems a broken PCV can cause.
Post by: fab5freddy on March 14, 2012, 12:31:29 pm
Doesn't mean it hasn't failed.

I'd get it checked mate, first port of call  :happy2:
Title: Re: problems a broken PCV can cause.
Post by: smokey on March 19, 2012, 11:27:23 am
Do TDI's have this?

I took my engine cover off the other day and noticed some oil underneath which looks like it might have come from the oil cap?!

Thanks