A worn 4L80E stator shaft or pump drive cuts line pressure and starves clutches of apply force. Catch the wear before it cooks your rebuild.
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The part for this fix
4L80E Front Pump Gasket 1991-2013 OEM 8677782
$12.99 · In stock
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What the stator shaft does
- Center support for the torque converter stator
- Carries pump pressure to charge circuits
- Houses the TCC apply seal
- Reacts torque from the converter
What the pump drive does
- Driven by the converter hub
- Spins the pump rotor
- Generates all hydraulic pressure
Symptoms of wear
Stator shaft wear:
- Low line pressure (especially hot)
- Sloppy shifts
- TCC slip
- Sometimes loud whine
Pump drive wear:
- Pump output low
- All gears slip
- Burn-mark on converter hub
- Sometimes complete pump failure
Diagnosis
Pressure test:
- Tap a gauge into line pressure port
- Spec at idle: 60-80 PSI
- Spec at WOT: 150-175 PSI
- Below spec = pump or stator issue
Drop pan:
- Brass particles on magnet = bushing wear
- Aluminum flake = stator shaft galling
Replacement parts
OEM stator shaft:
- AC Delco 8642186
- $180-$300 part
- Comes as assembly with bushings
HD stator shaft:
- Sonnax 34960C
- Hardened wear surfaces
- $300-$500
- Required for tow/HD use
Pump drive components:
- Pump rotor: $80-$140
- Pump slide: $40-$80
- Pump body bushing: $20-$40
- Sealing rings: $30-$60
Install
- Trans must come out
- Pump assembly comes off front
- Stator shaft unbolts from pump body
- Inspect pump body for wear
- Replace all bushings during reassembly
- Reseal pump body with new gasket
Cost
DIY full pump rebuild:
- HD stator: $300-$500
- Pump rotor + slide: $120-$220
- All bushings: $80-$140
- Gaskets + seals: $50-$100
- Fluid (Dexron VI, 12 qts): $110-$170
- Total: $660-$1,130
Shop rebuild including pump:
- Parts: $660-$1,130
- Labor: $1,400-$2,200
- Total: $2,060-$3,330
Always replace converter at same time
- Worn pump drive = worn converter hub
- New pump + old converter = same wear in 10k miles
- Pair the upgrade
HP application notes
- Stock pump good to ~500 ft-lb
- HD truck use: 450 ft-lb sustained kills it
- HD stator + HD pump body required for 600+ ft-lb
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