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Calling all RB25DET experts...

driving yesterday under some load out of second gear there was a weird pop amongst the bov sound when i shifted to the third, car felt fine, although a noticable change in the bov sound was evident.

I opened the bonnet and found a valve of some description had broken.

Between the plenum and the BOV i had a small valve, some say its a one way valve which was like two small black discs with a clear centre section from memory, ( i say from memory as the centre section looks to have shattered and disappeared!)

This meant that the vaccum line between the plenum and the bov was effectively disconnected, car still boosted, but obviously no bov. I have fixed the problem with some new vaccum line , this time without the small valve.

Now this valve doesnt appear to be standard as a i checked out some other R33's last night and none had a valve fitted.

anyone else got one of these or know exactly what they do?

car is fine now

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https://www.sau.com.au/forums/topic/4029-oops-i-broke-something/
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I never had a valve in that line on my GTST. When i installed my GFB BOV I actually took the old pipe off and replaced it with a new bit of pipe. Car runs perfectly.

All I can think of is it might have been a small inline filter or something, although I am sure that if having one there was important Nissan would have put one there...

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