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Old 08-13-2013, 06:32 PM   #35
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Join Date: Oct 2011
Location: Portland de Oregon
Default Stock BOV flow directions

Originally Posted by AdmiralSenn View Post
Unfortunately there was also a loud POP, which it turns out is from a Bosch valve, item # 0280142105. This seems to be a Saab overpressure valve, which seems to have taken the place of the external CBV that the T3 in the car came with. It was venting to atmosphere, so I guess it's sort of a BOV given the way it's plumbed.

In fact, the more I look at it the more I wonder if it was even hooked up to the correct port at all. The car has always had a strange noise off boost that sounded like really quiet compressor surge, but the previous owner said that it wasn't when I test drove it. This thing has some sort of vacuum diaphragm but pressure from that side wouldn't open up the valve at all as far as I can tell.

Is this a common modification? I don't remember ever seeing a reference to this being used on a Volvo before. It looks like I have an oddly numbered variant, I just found a bunch of threads describing very similar parts with final digits off by one or two. Can anyone who's used one of these tell/show me how it should be plumbed?
I'm looking back on your thread, did the BOV get figured out, as mentioned above? If the blow off valve isn't configured right, it certainly could be causing problems.

See this post: Is this what you have?

Then this image shows how air flows through a stock system. However, the BOV is different than the Bosch. and NOT SHOWN: The vacuum hose running from manifold to BOV.

Stage Zero Is A Smooth Machine (I'm not a racer but I play one on TB) 1986 740 Turbo wagon
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