Hey guys I had been noticing a bit of a boost leak and when I put it on the dyno about a month ago was suspicions were confirmed. Would make 21pound and then fall off to 17 on the high boost tune and then with the everyday tune it would make 18 and then fall off to about 15-16. 

 

Started to investigate and found the bov was on back to front. So what would usually be the outlet was now the inlet. After changing it back to how it should be it now holds 21 pound and goes a lot better. 

 

Is there a reason why it would be leaking through because it was back to front? Or could it just be a sign that it's not that healthy and may need replacing. I can't think of a reason why it leak being installed backwards. 

 

Cheers

what make/model of BOV is it?

Picture of bov? Makes sense. Not made to seal with pressure on a vent port.

Block bov

/end thread

Whilst I agree with this ^^, it doesn't help to answer the bloke's question - he's already resolved the leak by putting the BOV around the correct way haha

Even if it was around the incorrect way blocking fixes it

/end thread

Standard bov. 

 

I wasnt asking how to fix it. Was asking if anyone had any ideas why it was doing what it was doing. But thanks for your input. 

Search bosch bypass valve. Weird diaphragm setup in them. Might give you a visual as to why it leaks the wrong way around.

16 minutes ago, Jamie_d said:

Search bosch bypass valve. Weird diaphragm setup in them. Might give you a visual as to why it leaks the wrong way around.

Cheers for that.

 

In my mind I thought as long as it had the manifold pressure there it would have held closed unless there was a leak/ hole in the diaphragm. But then it would have leaked regardless of if it was installed the correct way or not.