Common Fluid Leaks, 7.3 Edition: Symptoms, Causes, Prevention and How To Fix Them
Posted by Adam Blattenberg on Jul 16th 2025
7.3L Powerstroke owners have always been ridiculed for marking their territory (i.e., leaking oil, leaving spots wherever they park). We’re going to plead the Fifth on the validity of that statement, but in the interest of not marking driveways (and helping you keep your Powerstroke on the road), we thought we’d share the most common leaks, their symptoms, how to prevent them, and how to fix them.
7.3 Powerstroke Common Fluid Leaks (listed in no particular order)
1. Turbo Pedestal Oil Leaks
Symptoms:
- Oil in the engine valley
- Burning oil smell near the turbo
- Oil drips down the rear of the engine and bellhousing (can look like a rear main seal leak)
Cause: Most commonly, the EBPV is leaking. Also, leaking O-rings on the turbo pedestal are common.
Prevention: Rebuild or replace EBPV every few hundred thousand miles or so (or remove the EBPV altogether). Replace pedestal seals with quality Viton O-rings during turbo removal/replacement
Fix: If EBPV is leaking, remove and rebuild, or replace EBPV (depends on damage found)(can also remove EBPV altogether with a non-EBPV pedestal). If pedestal is the leak, remove the turbo and pedestal, replace all four O-rings (including EBPV if equipped)
2. HPOP (High-Pressure Oil Pump) Leaks
Symptoms:
- Oil in the engine valley
- Hard starts, especially hot
- Oil running down the rear of the engine, collecting near the rear transmission inspection plate (may also look like a rear main leak)
Cause: Leaky Serviceable HPOP plug, Rear Cover Oring, HPOP line fittings, or, less commonly, the mounting gasket
Prevention: Use updated STC fittings and reseal the HPOP while also replacing the Serviceable Plug
Fix: Remove the fuel bowl to access the HPOP, and replace leaking components
3. Oil Cooler Leaks
Symptoms:
- Oil in coolant or coolant in oil
- External coolant or oil leaks near driver side of engine is most common
- Overheating or oil pressure drop
Cause: Failed O-rings on the oil cooler
Prevention: Replace O-rings every 100k miles or so
Fix: Drain coolant and oil, remove oil cooler, install new O-rings, reassemble
4. Valve Cover Gasket Leaks
Symptoms:
- Oil seeping around valve cover
- Oil smell or visible smoke from engine bay when hot (oil drips on the exhaust manifolds)
- Electrical faults (injector or glow plug issues)
Cause: Degraded UVCH gasket or harness connector
Prevention: Don’t overtighten, use quality OEM replacements
Fix: Remove valve cover, replace gasket, and inspect UVC harness
5. Fuel Bowl/Water Separator Leaks
Symptoms:
- Fuel smell
- Fuel in engine valley
- Hard starts or long crank time
Cause: Old fuel heater seals, failed drain valve, or cracked bowl (less common)
Prevention: Replace seals with high-quality Viton kits
Fix: Remove and rebuild or replace bowl; reseal all fittings
6. Injector O-ring Leaks (Oil or Fuel) (internal leaks only)
Symptoms:
- Oil/fuel in cylinder or combustion chamber
- Rough idle or white/blue smoke
- Oil leaking around base of injector(s)
- Black fuel filters (from oil contamination)
- Low ICP
Cause: Worn O-rings on injectors
Prevention: Use OEM or high-quality seals during injector work
Fix: Remove valve cover, pull injectors, replace O-rings
7. Transmission Cooler Line Leaks
Symptoms:
- ATF puddles under truck (near front or under the cab)
- Transmission slipping or overheating
- Low trans fluid level
Cause: Worn rubber sections or leaking fittings
Prevention: Check and secure lines. Clean caked on mud from lines and cooler
Fix: Replace leaking lines or hose sections. Repair or replace fittings as needed
8. Rear Main Seal Oil Leak
Symptoms:
- Oil dripping between the engine and transmission
- Persistent low oil level
Cause: Crank seal wear or groove on crankshaft
Prevention: Maintain proper crankcase ventilation and oil level
Fix: Remove transmission, replace rear main seal, install wear sleeve if needed
9. Power Steering Pump or Line Leaks
Symptoms:
- Whining noise when turning
- Fluid leaks near front driver's side
- Steering feel becomes heavy or inconsistent
Cause: Leaky pump seal or hose
Prevention: Do regular fluid changes. Keep fluid reservoir full
Fix: Replace leaking pump or hose with a quality replacement
10. Radiator or Degas Bottle (Coolant) Leaks
Symptoms:
- Coolant puddles and/or coolant colored deposits in engine bay
- Overheating
- Steam or low coolant light
Cause: Cracks in radiator end tanks, hoses, or degas bottle. End tank separation from the radiator core is also common.
Prevention: Maintain cooling system pressure (replace or test the degas bottle cap regularly), flush the coolant system regularly, use the proper coolant, and replace old hoses.
Fix: Replace radiator (or tighten the end tank securing tabs), degas bottle, or hoses; consider aluminum and silicone upgrades.
***Disclaimer: The information provided on this blog is for informational purposes only. We share our knowledge and experience, but we are not liable for any damages, injuries, or losses that may occur as a result of using this information. Situations are rarely cut and dry in the automotive world. Your situation will likely be somewhat different than what we describe here. Use your best judgment and always consult a qualified professional for automotive repairs and modifications. Your safety is your responsibility.