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SUBJECT

DATE

Symptom Diagnostics - Oil Leaks

January 2017

Additions, Revisions, or Updates
Publication Number / Title

Platform

Section Title

DDC-SVC-MAN-0191

GHG17 DD
Platform HD

Engine Oil Leaks

DDC-SVC-MAN-0084

EPA07/10/
GHG14 DD
Platform

These are new sections.
Engine Oil Leaks

All information subject to change without notice.

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Change

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2 Engine Oil Leaks

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Engine Oil Leaks

NOTE: Detroit™ and the Department of Transportation (DOT) define an external fluid leak as a condition where
fluids are pooling or leaking onto the ground.

Figure 1. Example of an Oil Leak - Very Wet with Evidence That Fluid Leaks onto the Ground

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Figure 2. Example of a Seep - Residue Accumulation on the Surface But Remains on that Surface and
Does Not Drip onto the Ground
NOTE: Block porosity is an immediate issue and does not happen over time. If there was a block porosity concern
present, the porosity issue would be evident when the engine is new.
Check as follows:
1. Shut off the engine, apply the parking brake, chock the wheels, and perform any other applicable safety steps.
2. Was an oil change recently performed on this vehicle?
a. Yes; check to make sure that the oil filter and drain plug were properly installed and clean any oil presence
spilled from the previous service interval.
b. No; Go to step 3.
3. Is oil pooling or leaking onto the ground?
a. Yes; Go to step 4.
b. No; no leaks are present, release the vehicle. Refer to 12WO-2. (http://www.ddcsn.com/cps/rde/xchg/ddcsn/hs/
5525.htm)
4. Check vehicle repair history. Are there any recent repairs that could have resulted in oil spills on the engine that would
appear as an oil leak?
a. Yes; examine the oil spill area of the engine to make sure it is not being perceived as an oil leak.
b. No; Go to step 5.
NOTE: Isolating the exact location can be difficult due to fan blast and road grime that can cause the leaking oil to
migrate. Oil leaks tend to move in a downward and rearward direction. Look for the highest point of any oil trace.
5. Inspect the entire vehicle for signs of leaks; note any leaks that could be confused for an engine oil leak. Was the
source of the leak identified as being caused by the engine?
a. Yes; Go to step 6.
b. No; identify the non-engine component causing the leak and refer to the component OEM literature for
additional information on troubleshooting/repair of the oil leak.

All information subject to change without notice.

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2 Engine Oil Leaks
6. Visually inspect the rocker cover gasket, starting at the left front of the engine and continuing down the left side
toward the rear of the engine. Is there an external oil leak coming from the rocker cover gasket?
a. Yes; replace the rocker cover gasket. Refer to section "Removal of the Rocker Cover".
b. No; Go to step 7.
7. Visually inspect the Camshaft Position (CMP) sensor for sign of external oil leaks. Is there an external oil leak coming
from the CMP sensor?
a. Yes; replace the O-ring on the CMP sensor. Refer to section "Removal of the Camshaft Position Sensor".
b. No; Go to step 8.
8. Visually inspect the camshaft housing seal, starting at the front left and continuing down the left side to the rear. Pay
special attention to the rear corner, as leaks are hard to see in this area. Are there any external oil leaks coming from
the cam frame housing seal?
a. Yes; replace the cam housing seal. Refer to section "Removal of the Camshaft Housing Assembly".
b. No; Go to step 9.
9. Visually inspect the cylinder head gasket (1), starting at the left front of the engine and continuing down the left side
to the rear of the engine. Keep in mind that the oil supply ports are at the front and the rear of the block. Are there any
external oil leaks coming from the cylinder head gasket?
a. Yes; remove the cylinder head and inspect the head gasket oil supply and return seals for damage.
Refer to section "Removal of the DD13 Cylinder Head Assembly"
Refer to section "Removal of the DD15 and DD16 Cylinder Head Assembly"
Repair as necessary.
b. No; Go to step 10.

1. Cylinder Head Gasket
2. Rocker Cover Gasket
3. Camshaft Housing Cup Plugs (behind
crossover pipe)
4. Camshaft Housing Seal

5.
6.
7.
8.

Oil Gallery Cup Plugs
Front Cover Seal (behind damper)
Crankshaft Seal (behind damper)
Oil Pan Gasket

Figure 3. Front of Engine (steps 10 - 13)
10. Is oil leaking from the front of the engine?
a. Yes; Go to step 11.
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11.

12.

13.

14.

b. No; Go to step 14.
Visually inspect the camshaft housing cup plugs (behind the crossover pipe) (3). Are there any external leaks present?
a. Yes; repair as necessary.
b. No; Go to step 12.
Visually inspect the oil gallery cup plugs (5) in the cylinder block. Are there any external leaks present?
a. Yes, repair as necessary.
b. No; Go to step 13.
Looking behind the damper, inspect for a leaking front cover seal (6) or a leaking crankshaft seal (7). Is either seal
leaking?
a. Yes; repair as necessary.
b. No; Go to step 39.
Is oil leaking from the right side of the engine?

1.
2.
3.
4.

Cylinder Head Gasket
Rocker Cover Gasket
Turbo Oil Supply and Return
Crankcase Breather and Tube

5.
6.
7.
8.

Oil Pan Gasket
Right Oil Drain Plug
Cylinder Block Cover Plate (if equipped)
Camshaft Housing Seal

Figure 4. Right Side (steps 14 - 20)
a. Yes; Go to step 15.
b. No; Go to step 21.
15. Inspect the right side oil drain plug (6). Is there an oil leak present at the oil drain plug?
a. Yes; repair as necessary.
b. No; Go to step 16.
16. Inspect the crankcase breather (4). Check for leaks at the inlet and outlet tubes, fittings, mounting surface to the
cylinder block, and the housing-to-cap seal. Are there any external oil leaks present?
a. Yes; repair as necessary, Go to step 18.
b. No; Go to step 17.

All information subject to change without notice.

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2 Engine Oil Leaks

NOTE: An internally leaking crankcase breather will leak at a rate of at least three drips of oil every five minutes. If
a leak is found at a slower rate than three drips every five minutes the source of the drip is not internal to the
crankcase breather.
17. Wipe the crankcase breather clean. Place a blank card under the crankcase breather assembly to visualize any leaks.
An internal leaking crankcase breather will leak at a rate of at least three drips of oil every five minutes. Are there any
oil leaks present of more than three drips of oil in a five-minute time span?
a. Yes; Go to step 18.
b. No; Go to step 19.
18. Measure the crankcase pressure. Refer to section "Crankcase Pressure Test". Does the engine have high crankcase
pressure?
a. Yes; repair as necessary.
b. No; replace the crankcase breather. Refer to section "Removal of the Crankcase Breather Assembly".
19. Is oil leaking at the boost pipe?
a. Yes; inspect for loose clamps, seeping, worn or damaged boost pipe and for a dirty air filter. Then Go to step
20.
b. No; Go to step 20.
20. Inspect the turbocharger assembly and related parts.
Refer to section "Inspection of the DD13 and DD15 Turbocharger"
Refer to section "Inspection of the DD16 Turbocharger"
Check for leaks at the inlet and outlet pipes, oil supply and drain lines, speed sensor, speed sensor O-ring, sealing
surface between the turbocharger assembly and the engine block. Are there any external oil leaks present?
a. Yes; repair as necessary.
b. No; Go to step 39.
21. Is oil leaking from the left side of the engine?

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1.
2.
3.
4.
5.
6.
7.

22.

23.

24.

25.

Injector Harness Grommets
Camshaft Housing Seal
Rocker Cover Gasket
High Pressure Transfer Line Seals
Cam Position Sensor O-ring
Cylinder Head Gasket
High Pressure Pump Mounting Seal

8. Oil Gallery Cup Plug between High Pressure
Pump and Air Compressor
9. Air Compressor Mounting Seal
10. Power Steering Pump Mounting Gasket
11. Left Oil Pan Plug
12. Oil Pan Gasket
13. Oil Thermostat Cover Plate Seal
14. Oil Coolant Module (see 13TS-10)

Figure 5. Left Side (steps 21 - 33)
a. Yes; Go to step 22.
b. No; Go to step 34.
Inspect the left side oil pan plug (11). Is there an oil leak present at the oil pan plug?
a. Yes; repair as necessary.
b. No; Go to step 23.
Visually inspect the oil pressure and oil temperature sensors for signs of external oil leaks. Leaks can be present at the
sensors or O-rings. Is there an external oil leak coming from either sensor?
a. Yes; repair as necessary.
b. No; Go to step 24.
Visually inspect the injector harness grommets (1). Are there any external leaks present?
a. Yes; replace the injector harness grommets.
b. No; Go to step 25.
Visually inspect the high pressure fuel injector line seals for each cylinder. Are any of the high pressure fuel injector
line seals leaking?

a. Yes; replace the high pressure fuel line injector line seal(s) that are leaking.
b. No; Go to step 26.
NOTE: When inspecting the oil coolant module, consider that oil might be spilled around the filler neck and oil
filter cap area during service intervals. These spills can sometimes lead to misdiagnosis.

All information subject to change without notice.

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2 Engine Oil Leaks
26. Inspect the oil coolant module. Check for leaks at the oil fill neck, oil filter cap, oil thermostat cover, plugs, and
around the sealing surface between the oil coolant module and the engine block. Are there any external oil leaks
present?
a. Yes; repair as necessary.
b. No; Go to step 27.
27. Inspect the oil dipstick tube. Are there any external oil leaks present?
a. Yes; repair as necessary.
b. No; Go to step 28.
28. Check for leaks at the High Pressure Fuel Pump (HPFP) (7). Are there any external oil leaks at the HPFP weep hole or
where the HPFP mates to the engine block?
a. Yes; Go to step 29.
b. No; Go to step 30.
29. Remove the HPFP and inspect its camshaft seal. Is damage present?
a. Yes; install a new HPFP and mounting O-ring.
b. No; install a new mounting O-ring and reinstall the HPFP.
30. Inspect the cylinder block oil gallery cup plug, located two inches under the high pressure fuel pump (8). Is there an
external oil leak at the cup plug?
a. Yes; replace the cup plug. Refer to section "Replacement of the Oil Gallery Cup below the High Pressure Fuel
Pump".
b. No; Go to step 31.
31. Inspect the air compressor assembly; check for oil leaks at the compressor's cup plug. Are there any external oil leaks
present?
a. Yes; replace the air compressor.
b. No; Go to step 32.
32. Inspect the air compressor flange where it mates to the engine block. Is there an external oil leak present?
a. Yes; remove the air compressor, clean the area, replace the O-ring, and reinstall the air compressor.
b. No; Go to step 33.
33. Inspect the seal between the rear of the air compressor and the power steering pump. Is there an external oil leak
present?
a. Yes; remove the power steering pump, replace the seal, and reinstall the power steering pump.
b. No; Go to step 39.
34. Visually inspect the camshaft housing cup plugs (1). Is there an external oil leak present?

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1.
2.
3.
4.
5.

35.

36.

37.

38.

Camshaft Housing Cup Plugs
Rocker Cover Gasket
Camshaft Housing Seal
Access Plate for #5 Idler
Rear Crank Seal (behind flywheel)

6.
7.
8.
9.

Flywheel Housing Gasket
Oil Pan Gasket
Access Plate for #3 Idler
Cylinder Head Gasket

Figure 6. Back of Engine (steps 34 to 38)
a. Yes; repair as necessary.
b. No; Go to step 35.
Visually inspect the camshaft housing seal (3). Is there an external oil leak present?
a. Yes; replace the cam housing seal. Refer to section "Removal of the Camshaft Housing Assembly".
b. No; Go to step 36.
Visually inspect the access plate for #5 idler (4). Is there an external oil leak present?
a. Yes; repair as necessary.
b. No; Go to step 37.
Visually inspect the access plate for #3 idler (8). Is there an external oil leak present?
a. Yes; repair as necessary.
b. No; Go to step 38.
Visually inspect the flywheel housing for leaks (6). Is there a leak on the lower 6 inches of the flywheel housing?
a. Yes; Go to step 39.
b. No; the oil leak is generated by either the flywheel housing gasket or the rear crankshaft seal. Inspect and repair
as necessary.

NOTE: For oil pan gasket warranty submissions, you may choose to use the image below to mark the location of
the leak on the oil pan gasket. When replacing an oil pan gasket, Refer to section "Installation of the Oil Pan".
39. Inspect the oil pan starting at the front of the engine working towards the rear of the engine. Is there an external oil
leak present?

All information subject to change without notice.

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2 Engine Oil Leaks

a. Yes; repair as necessary.
b. No; Refer to section "Engine Oil Leaks - Oil Developer Method".

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All information subject to change without notice.

Copyright © 2017 DETROIT DIESEL CORPORATION

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3

Engine Oil Leaks

NOTE: Detroit™ and the Department of Transportation (DOT) define an external fluid leak as a condition where
fluids are pooling or leaking onto the ground.

Figure 7. Example of an Oil Leak - Very Wet with Evidence that Fluid Leaks onto the Ground

All information subject to change without notice.