Oil and fluid leaks are just part of life when owning an older diesel. But they don't have to be permanent. Stop your 6.0L Powerstroke from marking it's territory, this list of the most common fluid leaks will help. 

6.0L Powerstroke Common Fluid Leaks (listed in no particular order)

1. EGR Cooler Leak (Coolant)

Symptoms:

• White smoke from exhaust
• Coolant loss with no visible external leak
• Overheating or degas bottle puking coolant

Cause: Cracked or failed EGR cooler

Prevention: Install an upgraded EGR cooler 

Fix: Replace with an upgraded EGR cooler

 

2. Oil Cooler Leaks / Restrictions

Symptoms:

• High oil temps vs coolant temps (delta greater than 15°F)
• Clogged coolant passages, often leading to EGR cooler failure
• Low coolant, overheating

Cause: Internal clogging from sand from the casting process and/or other debris (silicone gasket material is common)

Prevention: Regular coolant flushes with EC-1 rated coolant and install a coolant filter system

Fix: Remove and replace oil cooler; Flush cooling system thoroughly

 

3. High-Pressure Oil System Leaks (HPOP, STC, Dummy Plugs, Standpipes)

Symptoms:

• Hard hot starts or no start
• Long crank time
• ICP (Injection Control Pressure) low during cranking

Cause: Failed HPOP STC fitting, dummy plugs, or standpipes

Prevention: Replace leaking fittings (or upgrade to JIC equipped lines) and replace O-rings on standpipes/dummy plugs with new Viton seals

Fix: Remove valve covers, install updated parts; Test High Pressure Oil system with compressed air to pinpoint leaks

 

4. Degas Bottle / Cap Leaks (Coolant)

Symptoms:

• Coolant around the degas bottle or engine bay from a spraying leak
• Overheating due to pressure loss within coolant system
• Coolant “puking” out the cap

Cause: Failing cap or excessive pressure from EGR or head gasket issues

Prevention: Replace cap every 1–2 years; monitor pressure

Fix: Replace degas bottle cap or the entire degas bottle if cracked

 

5. Fuel Injector O-Ring Leaks

Symptoms:

• Fuel in oil
• Hard starts or poor running
• Loss of fuel pressure

Cause: Degraded or improperly installed O-rings on injector tips

Prevention: Use only quality O-rings (preferably Viton), inspect during injector installs

Fix: Remove injector, replace all O-rings, reinstall

 

6. Turbo Oil Drain Tube Leaks

Symptoms:

• Oil at rear of engine/turbo
• Smoking from turbo area
• Oil dripping from bellhousing

Cause: Worn O-rings or improperly seated drain tube. In rare instances, high oil temperatures can destroy O-rings too. Check your oil temp. 

Prevention: Replace O-rings any time turbo is removed

Fix: Remove turbo, replace drain tube O-rings, ensure tube is fully seated

 

7. Front/Rear Crankshaft Seals

Symptoms:

• Oil leaks from front or rear of engine
• Drips around crank pulley or bellhousing

Cause: Worn or hardened seals

Prevention: Maintain CCV system, don’t overfill oil

Fix:

Front: Remove balancer and replace seal

Rear: Remove transmission and flexplate/flywheel to access seal, and replace seal

 

8. HPOP Cover or IPR Valve Leaks

Symptoms:

• Oil accumulation at rear top of engine
• Hard starts, especially hot
• Possible ICP or IPR codes

Cause: Worn gasket on HPOP cover or IPR screen failure

Prevention: Replace IPR screen regularly, inspect for oil leaks at IPR/HPOP area

Fix: Remove turbo and HPOP cover, reseal or replace components

 

9. Power Steering Leaks

Symptoms:

• Whining noise while turning
• Loss of power assist or jerky steering
• Fluid puddles at the front driver side of truck

Cause: Cracked hose or worn pump seal

Prevention: Check fluid level and hose condition regularly

Fix: Replace leaking hose or pump; flush system

 

10. Transmission Cooler Line Leaks

Symptoms:

• ATF leaks near the radiator or under the truck near the transmission on the passenger side
• Transmission slipping or overheating
• Low ATF level

Cause: Deteriorated rubber lines or failed fittings

Prevention: Inspect and replace old lines; avoid over-tightening clamps

Fix: Replace faulty lines and fittings

 

11. Fuel Filter Housing Leaks

Symptoms:

• Fuel smell or visible drips
• Hard starts, long crank
• Fuel pooling in valley

Cause: Cracked filter cap, damaged WIF drain valve, or O-ring failure

Prevention: Use proper tools for filter changes; replace O-rings periodically

Fix: Replace damaged components; install Viton O-ring kit

12. Cylinder Head Fuel Leaks (cracked heads in injector bore)

Symptoms:

• Fuel in the coolant and/or diesel smell in the degas bottle
• Foamy or discolored coolant
• Rising coolant level (without overheating)
• Poor heater performance (air in system)

Cause: Cracked heads within the injector bores (extremely common)

Prevention: Replace heads with newer casting heads, which have thicker castings around the injectors for just this reason

Fix: Same as "Prevention"