August 10, 2005
Reference: Memo from H-D to dealers.

Diagnosing Oil Consumption **BE AWARE, NOTICE WHERE THEY'RE GOING WITH THESE SUGGESTIONS!!

(also posted in tech tips)
There has been a rise in oil consumption complaints on 2005 – 06 model year vehicles.
The intent of this Tech Tip is to help you determine if there is an actual oil consumption
issue and more accurately diagnose the root cause.
1. First, determine if there is excessive oil consumption by analyzing the customer
complaint and vehicle condition.
• Many times fuel delivery related issues cause smoking complaints and may even
gas wash cylinders leading customers to believe they have an "oil burner" on their
hands.
• Is the vehicle modified and what is its state of tune?
• Does the EFI calibration match the actual components on the vehicle?
• Is there fuel stand off in the air cleaner or manifold?
2. What is excessive consumption?
• Customers may not realize that all engines have some normal rate of oil
consumption, and air cooled engines are more prone to use some oil in the course
of normal operation. It would not be unusual for a Twin Cam engine to use one
quart of oil in 1500 miles or a middleweight powertrain to use one quart of oil in
1000 miles.
• Oil consumption is impacted by engine condition, mileage, duty cycle (how the
vehicle is operated and in what environmental conditions), and accessories.
• Is the vehicle through its break-in period? Remember rings must seat before they
will begin to seal the cylinder to piston clearance.
• After a discussion with the customer on the complaint and a brief inspection of the
vehicle you should be able to determine if you a dealing with a rich condition, oil
consumption complaint, or customer misperceptions.
3. Determine the real rate of consumption.
• To determine the rate of oil consumption bring the oil level to the full line following
the "Checking With Warm Engine" procedures outlined in the service manual and
tape the filler neck closed.
• Have the customer ride the vehicle and inspect the level at 500-mile intervals to
determine the actual rate of consumption. Be careful not to overfill the tank, as that
will provide a false indication of consumption.
• If the rate of consumption exceeds the norm, you will need to review duty cycle with
the customer and then begin your inspection of the engine's state-of-tune
accordingly.
August 10, 2005
4. Verify the system before you tear it down.
• Don't overlook the obvious items before disassembly. How are the oil hoses (tight
clamps, routings, etc.)?
• Verify breather operation, this might be a carry-over situation. If you blow lightly into
the breather snorkels, there should be some resistance if the umbrella valves are
closing properly.
• Verify oil pressure and oil return functions. You might be dealing with an oiling
system issue and/or a wet-sumped lower end.
• Take a compression reading and perform a leakdown test. Remember to write down
the numbers, Technical Service is sure to ask for them.
• If leak down exceeds 10% determine where it is leaking by. Into the lower end, out
the exhaust or intake port, or through a head gasket?
5. Now begin your disassembly based on your findings, and keep both eyes open
as you take things apart for clues to the root cause.
• If the leakage was primarily into the crankcase, then you are chasing a piston to
cylinder sealing issues. To rule out a barreled or tapered cylinder re-check leak
down in three places (top - middle - bottom) in the stroke once the rocker arm
support plate is removed.
􀂃 By the way how did those umbrellas look, and was the rocker box fairly well
scavenged? No clogged return passages right? No signs of leakage at the head
gasket oil returns? Good gasket surfaces?
􀂃 Check the piston crown for carbon build up. Washed areas on the edges of the