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MarkRobinson MarkRobinson is offline
Architecture & Porsche's
 
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
Ok I'm re-hatching this issue> Last sunday on the way back from a car show my scavenge pump stopped working about 2m from the house during a high-rpm deceleration.

My car: '94 Turbo 3.6 CIS powered '91 911 turbo, 6k on fully rebuilt 3.6 with misc. mods. Pump has 262k miles on it.

I thought it was a turbo seal but on a whim decided to test the pump's suction. During a turbocharger change back in 2001, the scavenge pump could have sucked my thumb off my had the suction was so strong...at this last test, there was barely the suction as if I were pulling through a straw via mouth: next to none. Oil flows out the bottom of the tank as per this and a prior thread flow photos, so I'm quite sure oil flow is significant, adequate, and common. Both tests were at-idle on a cool engine.

I read this thread and another and decided to remove the pump, check the pin, check the two M6 socket headed screws, check the two seals on the pump, check for damage, and pressurize/check for leaks on the brass oil return line and joined -8an line that runs to the B&B scavenge tank.

Line was crack/leak free, so I cleaned it an proceeded to the pump, which was also in perfect working condition in all respects: seals, gears, bolts/studs, pin, etc.

Upon reassembly, the pump spins freely and you can feel suction on the banjo side and pressure on the "out" upper section of the pump. Before the rebuild it also demonstrated the same suction/pressure on the pump: bear in mind I'm merely twisting it with my fingers.

The ONLY possible thing I could find is that the drive pin that engages the two M6 Socket headed screws: the two screws heads have flattened areas near the top edge of the head of each bolt, indicative that the pin was engaging the heads at the very top. I swapped the bolts so that the pin would have a rounded contact, just in case the flat area had somehow allowed the pin to slip past it.

charging my battery, and i have a clear glass of oil submerging the end of the scavenge line and will have the wifey hold a cup under the catch can outlet: 10-20s of run time will show if I somehow rebuilt this and removed a major hiccup in the otherwise flawless system.

Anyone have any other thoughts?
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'89 Andial 951
'82 928R
'74 911 RSR 3.6
Old 06-16-2013, 04:44 PM
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