EVO: Oiling & Lubrication

Oil Leaks

First and foremost, do not use silicone sealer on any engine, oil pump or related parts or gaskets to stop a leak.
The heat coupled with crankcase pressure pulses can break pieces of it loose and send them through the engine.
These pieces may stop up oil passages and starve the engine of oil.
The gaskets / seals made for Sportsters are more than efficient for stopping leaks.
If you have continual leaks after installing new gaskets, chances are it's not the gasket's fault.
There may be manufacturing, fitting, high internal pressure pulses, warped sealing surfaces or other issues to address.

Silicone can break up into small film sheets and float around the oil path stopping up the small restricted passages.
Both feed and return sides of the oil pump create suction on their inlet sides as they rotate.
The feed side of the pump is gravity fed from the tank and the feed gerotors send pressure into the engine.
It is mainly dependent on gravity oil from the tank.
The scavenge side of the pump is fed by crankcase pressure pushing the oil to the scavenge port in the crankcase.
It is more dependent on the flywheels to get the oil to the scavenge port.
If there is an obstruction in the return path from the crankcase to the oil tank, it will slow the flow of oil out of the engine. This can cause weak or no oil flow.
If the scavenge side of the oil pump is not flowing oil fast enough to the tank, oil will build up in the sump.
This can result in higher crankcase pressure, more oil film spinning around the flywheels, engine drag, blowing rocker box gaskets and general oil leaks.
In an instance where used silicone was used to seal the gaskets, pieces of silicone (or sheets) could be sucked in, stretched and broke off into the engine.
This silicone 'gummy bear' sheet was found in the oil pump.

An oil leak could also be a crankcase pressure problem. A situation where the engine is both blowing out and then pulling in air from the rocker box gaskets.
04-up engines seem to be more susceptible to crankcase pressure problems.
It's important to inspect and change out the breather valves periodically. Read more about the breather valves below.

Oil Consumption Service Bulletin - August 10, 2005

Article by Krayven Sumhead of the XLFORUM 2)

Diagnosing Oil Consumption
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.
  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 piston crown are a good indication of an “oil pumper” (bad rings or piston to cylinder fit). Solid carbon build up across the piston crown generally indicated it is coming from above.
      * With the cylinders off you will be able to more closely examine (and take note of) ring end gap locations. Do they match the service manual recommendations or are they lined up? Also, check the second compression ring, also called the middle or scraper ring, installation. The “dot” should face up, but even more important the outer bevel slants toward the piston and it has a slight chamfer on the ID that goes to the bottom to allow it to function properly. It is rare but sometimes the “dot” is up and ring's taper face is wrong.
      * While you are looking at the rings check their wear patterns. A ring that is over spread or twisted during installation will not seal properly.
    • Leak down past the valves and into the ports requires you inspect them for bad seats and bent stems, or you may find carbon built up to the point they just were not able to seal the combustion chamber.
      * Heavily carbon’ed valves and oil in the intake or exhaust ports are indications of leaking valve seals.
      * It also pays to look for the unusual, like leakage between the valve guide and the cylinder head. Are the guides loose? Was the head's guide bore scored or damaged during guide installation? This can sometimes be indicated by unusually clean or unusually golden patches in specific spots around the guide. The same is true if there is actual porosity in the head.

Valve Seal Updates - August 10, 2005

  • 2005 models and early production 2006 vehicles use a one-piece valve seal and lower spring seat design (p/n 18094-02) that can cause oil leakage between the guide and the seal when side loaded or miss-installed. These can be identified by the silver seal ring and black rubber material.
  • A new version one-piece valve seal and lower spring seat design (p/n 18094-02A) is being implemented into service parts to improve sealing properties and minimize installation issues.
  • The first batch of this new seal can be identified by a green seal ring as shown below. Towards the end of the month 18094-02A seal kits will change to an orange colored rubber material to improve visual identification of the new parts.
  • Twin Cam 88/88B production will be moving to this design in the near future with middle-weight powertrain and service parts to follow shortly thereafter.
  • Please utilize this new design during any future top end services.
  • Warranty and Service Procedures
  • Any individual 18094-02 valve seals in your inventory may be used on Middle-Weight Powertrain repairs.
  • Current engine gasket kits may be used on 2004 - 2006 Sportster and 2003 - 2006 Buell engines.
  • Current gasket kits (top end p/n 17052-99B and engine p/n 17053-99A) may also be used on 2004 and earlier Twin Cam 88/88B engines without any special steps.
  • When using current gasket kits (top end p/n 17052-99B and engine p/n 17053-99A) on 2005 and 2006 Twin Cam 88/88B models discard the 18094-02 valve seals included and use part number 18094-02A in their place, and the included seal protector during installation.
  • For warranty repairs that involve the use of these engine gasket kits (p/n 17052-99B & 17053-99A), you may also claim 1 valve seal kit p/n 18094-02A as part of the repair.
  • These additional parts will only be allowed on MC warranty claims filed against your existing inventory of gasket kits used to repair 2005-2006 Big Twins.
  • Future kits will have the new valve seals included so additional parts should not be listed on warranty claims. 18094-02A Valve Seal Identification

Diagnosing Oil Leaks

Obviously you must find exactly what is leaking before you can determine what will be needed to fix it. 3)
Degrease the area in question and run the bike a little and watch the area for the beginning signs of seepage.
Check torque on the bolts on covers and parts with gasket/seals but do not tighten more than the specs in the FSM to stop a leak.
That may result in stripping the threads.
If you have a gasket / seal that has needed replacing several times, you must find the cause of the continued failure and then repair that.
In some cases, a considerable amount of the engine has to be disassembled just to get to the problem. Refer to your FSM for the proper procedures.
Always keep a close watch on oil levels if you know you have a leak.

Overfilled Oil Tank

Read more on Overfilling the Oil Tank in the REF section of the Sportsterpedia.
Before topping off the oil tank, run the engine if possible for about a 30 min. ride.
This heats up the oil to operating temperature and suspends the solids in the oil instead of it laying on the bottom of the case.
This also allows the oil pump to send most of the oil in the engine back to the tank before you add more so you get a more accurate account of the oil level.
Failure to warm the engine first can result in an overfull condition in the system and you can end up blowing the cap off the oil tank and a big mess.
Overfilling your oil tank can also result in engine drag (wetsumping) and puking oil out the air cleaner.
The oil tank is vented to the gearcase / cam chest in the engine using a stand pipe in the oil tank.
When the tank is slightly over filled, oil that was standing in the sump is added to the tank via the oil pump, thus raising the level in the tank.
The excess oil in the tank will either flow back into the gearcase via the tank vent or up and out of the oil cap.
Excess oil that returns to the gearcase through the tank vent is picked up with crankcase air pressure and blown out the engine breather valve(s).
So, depending on your venting setup, oil can be blown into the air cleaner or out the vent lines due to overfilling the oil tank.

Visual Inspection

Leaking with engine running

  • Degrease the bike until there's no oil remaining.
    Then take some Soft n Dri (women's antiperspirant spray), talcum powder etc. and spray it around the rocker gaskets (or other suspected leaking area). 4)
    It will go on clear but when it gets heated will turn to a white powder. Just a light film is all it takes.
    Whenever it starts leaking it'll show up exactly where the leak is.
  • Clean the engine, then start it and use a bright light to see where the leak is coming from. 5)
    The light should make the liquid oil shine. You may only have to run your scoot for a few seconds to start leak.
Rocker boxes sprayed with powder antiperspirant to detected oil leaks. 6)

Leaking with engine shut off

  • Clean the area thoroughly (like with rake cleaner and air blow dry). 7)
    Let it sit long enough to begin leaking and blow some talcum powder aver the area.
    The talc will stick to the oil and pinpoint the origin.
  • Take an old bike tube and cut a piece while retaining the valve stem. 8)
    Use a hose clamp to tighten it over the filler neck on the oil tank.
    Then put a lb are two of air pressure on it and see if that helps you locate where it's coming from.

Leaking out the breather vent(s)

  • If you've installed external breather vent hoses, make sure there are no kinks in the lines(s) that would stop or slow down the engine from breathing.
    This would bottle up crankcase pressure and cause the internal pressure to implode the gaskets and create a leak.
    Also make sure there are no obstructions (sludge) in any bends that may be in the lines.
    However, a few drips of oil out a vent hose while parked is normal.
    This does not qualify as oil 'puking' out of the vent (which is more of a sudden rush of oil).
  • In a perfect world, you would only have a slight oil mist coming out of the crankcase breather which could easily be routed into the air cleaner.
    (keeping the E.P.A. happy by depositing the oil back into the engine instead of dripping on the ground).
    On 91-up Sportsters, this problem has been almost eliminated with the OEM breathers venting into the A/C.
    But the problem still appears on 90< Sportsters and newer models with external vent lines added.
  • The breather vents usually work fine on OEM engines. Problems have been noted however when bigger pistons / performance upgrades have been added.
    Engine upgrades sometimes comes with extra baggage.
    Bigger pistons brings with it more air displacement under the pistons (higher air volume in the lower case).
  • Heavy oil flow 'puking' from the breather vent(s) only on cold start up could be from a sit-sumping condition where oil is draining into the sump when parked.
    Your motor may be filling with oil while the bike is not running and it all gets pushed out the breather when you start the bike.
  • Known causes for 'sit-sumping' include:
    • Oil seeping past the oil pump check ball / check valve. Often this can be corrected by simply replacing the ball or valve in question.
      In more severe cases the check-ball seat may need to be resurfaced.
    • Clearances in the oil pump or gerotors out of service limit.

Internal Inspection

Check the breather valves (umbrellas)

The umbrella valves are simple rubber flaps that will get hard over heat and time.
They should be inspected periodically for hardness and replaced if they are not soft.

  • 86-03 umbrellas are now obsolete parts. You may find some NOS ones at your local dealership or online.
    An alternative is to install an external reed valve inline when your OEM umbrella fails.
  • 91-03 models have the umbrellas visible with the top rocker box section removed.
  • 04-up umbrellas are not replaceable themselves as they are built inside the 'replaceable' plastic breather valve assembly.
86-90 cap, tube and umbrella 9) 86-90 breather baffle tube installed 10)
91-03 breather valves 11) 04-up breather valves 12)

Check the spark plugs for oil fouling

Check intake and exhaust ports in the heads

You can pull your exhaust pipes and intake manifold and look at the valves to see if the oil is leaking past the valve stem seals. 15)

16) 17) 18)

Check oil smudge marks when removing the heads

When dismantling the top end (or to bring parts to your mechanic)and before cleaning the head gaskets / surfaces, check them for oil smears. 19)
Smudge marks can be a give away as to where any leaks might occur. Also take a few pics of them (no flash, direct light and a steady hand).
The gasket has been known to raise around the head oil drain and only on the inside edge of the gasket.
So no outward sign of the leak. With the head removed an experienced eye may be able to spot the problem.

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