Volvo By-pass Valve

Modifying the Valve to work on a SVO.
The Volvo 740 turbo also has an integrated boost by-pass valve to eliminate turbo damage from 'instant' throttle lift.  The unit is a cast piece with attaching bracket.
by-pass front by-pass rear
Boost by-pass front view Boost by-pass rear view
The internal view shows how it works.  The valve is located close to the compressor outlet and is vacuum assisted.
by-pass valve with bracket removed
Boost by-pass valve without bracket
The unit is made in Germany by a company called Pierburg.  All three valves I looked at had the a part number of 7 21007 00 located on the top of the diaphram housing.  There are additional numbers on the housing but they seem to differ (i.e. 1336380 or 1389225). Scott Shidel is using the 1336380 unit.
by-pass valve top
Boost by-pass top, notice the part
number on top.
Special thanks to Scott Shidel for sending me the inital information which made it possible to get these pictures from the yard.
Modifying the Valve to work on a SVO
The bracket on the Volvo By-pass is really not needed, for my application, so I cut most of it off and just just the outlet tube.
bp-bypass1.jpg (35921 bytes) bp-bypass2.jpg (32378 bytes)
bp-bypass3.jpg (19833 bytes)
  • Top left: The assembled by-pass valve.
  • Top right: The by-pass valve with bracket mostly removed and disassembled.
  • Bottom: By-pass valve re-assembled
I then took the Volvo elbow (Volvo P/N: 1336438) and forced the by-pass inlet in to the elbow and positioned the valve to relieve pressure in front of the turbo. Check out these assembly pictures.
bp-bypassass1.jpg (35840 bytes)
bp-bypassass2.jpg (33331 bytes)
bp-bypassass3.jpg (38841 bytes)
bp-bypassass4.jpg (23444 bytes)
bp-bypassass5.jpg (27039 bytes)
bp-bypassass6.jpg (28035 bytes)

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