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All Spooled Up
Join Date: May 2009
Location: Between NE and Central PA
Posts: 2,516
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Reason why stock WG's fail.
It looks like I just uncovered the reason that the stock WG's seem to start leaking pressure before they are suppose to open. After using a cup style wire wheel on a die grinder (where it spins so fast that it spreads out like it is a flat style wheel) to clean up the valves and seats on 2 stock WG's, I saw that each one had several cracks in the seats. Looks like I'm going to have to get one of then re-seated. Will head shops replace the valve seat on one of these units?
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>gray 89 951S - K27/8, MAF, 3" intake, 3" exhaust w/separate waste pipe, 55# inj, late cam; >red 87 924S - chip, K&N, punched-out cat&muffler >black 80 924 - (sold) >maroon 77 924 - auto (sold) |
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11-16-2010, 04:21 AM
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All Spooled Up
Join Date: May 2009
Location: Between NE and Central PA
Posts: 2,516
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Upon closer scrutiny it appears that, although the cracks are WHY the stock WG's leak, it probably isn't WHERE they leak. The cracks are only hairline, so any leakage through them would be insignificant. The problem appears to be that the edges of the cracks that face the valve head curl out slightly, causing it not to be able to fully contact the seat. The good news is that a good lapping would probably do the job, in getting it to seal up nicely again. It probably would need to be re-done every few years, or so.
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>gray 89 951S - K27/8, MAF, 3" intake, 3" exhaust w/separate waste pipe, 55# inj, late cam; >red 87 924S - chip, K&N, punched-out cat&muffler >black 80 924 - (sold) >maroon 77 924 - auto (sold) |
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11-17-2010, 06:40 AM
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Quality
Join Date: Oct 2007
Location: Philadelphia area and Morristown NJ
Posts: 951
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Pics of these things help. =)
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85.5 944 NA 5spd - Sold but not forgotten 89 951 Turbo S - Revival in progress... 
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01-11-2011, 09:31 AM
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Registered
Join Date: Jan 2007
Posts: 2,370
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I would think that your seat could be cut as well as the wastegate valve head and then lapped at any motor rebuild machine shop. The hairline cracks would concern me though. The seat may come apart and come out in little pieces possibly. You might want to look into getting a new seat installed and have the wastegate valve head cut to the seat. Or why not just buy a good used wastegate. They are available and relatively inexpensive.
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01-11-2011, 02:55 PM
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Registered
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Cleaning those 25 year old wastegates Im sure will help the matter but while its apart I would just buy new springs for them so that they effectively hold your exhaust gas in turbo tract under full boost as this is the main solution to everyones problem!
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'83 944 ROW zermatt silver/black, sunroof & A/C factory deleted, houndstooth sport seats, 7Q - 220 LSD short fifth, F & R 23.3 MM 951 M030 suspension, 16" fuch's, manual windows, club sport mirrors, Blk/Wht gauges, rear seats & all sound deadening removed, 968 rear wing, fiberglass hood & 937 F bumper |
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01-11-2011, 04:05 PM
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Wild man, Why not just get a LR wastegate?
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01-23-2011, 06:32 PM
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Super Moderator
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penny pinching.
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'89 turbo-s (2.7, wolf3d ems, garrett dbb turbo, tial 46mm, etc. fast!) |
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01-24-2011, 12:22 PM
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Porsche 944
1989 Duh? 951
