Everyone knows that
Harleys don't leak oil, they just mark their spot! (ever seen those signs
that say "Washington stayed here"?)
Evolution ('84-'99) cylinder base and rocker box gaskets are a very common
spot for leaking oil. The usual causes can be uneven mating surfaces,
improper gasket installation or torque procedures, or improper warm up
procedures by the operator.
I can't stress the need for warming up your bike before riding enough.
When the cylinders warm up they expand (or grow), increasing the pressure
on the gaskets. If you don't let your bike warm up, there won't be enough
pressure on the gaskets to keep them sealed.
Inner primary seals and transmission shifter shafts are also a very
common spot for oil leaks.
Obviously you must find exactly what is leaking before you can determine
what will be needed to fix it. Degrease the area in question and run the
bike a little and watch the area for the beginning signs of seepage. The
use of a spray-on powder deodorant will help pinpoint the exact
leak.
The only hope of curing a gasket or seal leak is to replace it, simply
trying to make the bolts tighter will never stop a leak and will probably
just strip out the threads. The only gasket sealer I will recommend is
Hylomar (available at most automotive supply stores), never use any kind
of silicone anywhere internally in your motor or where there is oil flow
to the motor, it can break off and block oil passages. Hylomar will
dissolve in the hot oil. It might plug up your oil filter but that's
better than completely stopping oil flow to critical areas. If you have a
seal near a bearing or shaft that has needed replacing several times
it's probably pretty likely that the bearing is getting loose or the
surface of what is riding against the seal is distorted in some way. You
must find the cause of the continued failure and then repair that. It's
really a pretty simple concept, the biggest problem is that in most cases
a considerable amount of motorcycle has to be disassembled just to get to
the problem. Refer to your service manual for proper procedures.
It is rare for an oil leak to cause any damage, the damage is usually a
result of the lack of oil after it has leaked out. Always keep a close
watch on oil levels if you know you have a leak.
If you ride an older bike (Pre-Evo) you will find that all us old-school
guys know not to worry about if our bikes leak oil, the time to worry is
when it stops leaking.
Oil Leaks from the
Crank Case Breather / Air Filter
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, aiding the filter's
ability to capture dust particles before they enter the engine and also
keeping the Safety Nazis at the E.P.A. happy by depositing the oil back
into the engine instead of dripping on the ground (We take oil out of the
earth, God forbid that we would ever let any drip back in!) With the
TwinCam motors and later model Sportster this problem has been almost
completely eliminated but can still appear in motors with performance
upgrades.
Originally the problem
of oil coming from the breather was a leftover from the "total
loss" oiling system where all of the oil was supposed to drain onto
the ground instead of back to the oil tank. Harley has made some pretty
good improvements since those days but part of the breather problem has
hung on for a while now.
The most common reason
for oil coming out of the breather/air cleaner is simply from over filling
the oil tank. The oil tank is vented to the gearcase in the engine using a
stand pipe in the oil tank, when the tank is slightly over filled it will
be fine until the oil starts to get warm and expands, raising the level in
the tank until it flows down the vent tube and into the gearcase. The
excess oil in the engine is blown out the breather (which vents into the
air cleaner through the heads on later models.)
Do not try to fill the oil tank to the "Full" mark on the stick,
always run it with the oil level just below the full mark and above the
add mark when the oil (not just the bike) is hot.
ANYTIME there is an excessive amount of oil coming from the
crankcase breather it is because either the collection and scavenging
system is malfunctioning, leaving too much oil in the bottom end (crank
case). This could be because oil is not being pumped out of the engine as
fast as it's being pumped in (small pieces of metal passing through the
oil pump can damage the return side of the pump and reduce the flow back
to the tank.) or bad umbrella valves may prevent the air and oil from the
breather from separating properly or blocked/pinched vent lines or oil
passages. There are a number of reasons - Your mission, should you choose
to accept it, is to find that reason. I can't find the reason your
bike is doing it with just email.
J&P
Cycles and Custom Chrome inc. (CCI) sells a kit called "The
Cure" and it has proven to work very well in Evo BigTwins ('84-99)
and Evo Sportsters ('86-) with reducing the amount of oil carry-over.
Another solution is to just reroute the breather away from the air cleaner
to an inline breather filter (never leave the end of the line exposed to
dirt and debris) and mount it somewhere on or under the bike. It will
still drip a drop or two on the driveway (or living room floor, whichever
the case may be) but at least it's not dripping on the nosecone or blowing
back onto your leg.
Heavy oil flow from
breather,
but only right after start up
If you notice that you
have a bunch of oil puking at start up but it stops after a minute or two
of running, that's an easy one. If your motor only pukes at start up that
means that the crankcase is filling with oil while the bike is not running
and it all gets pushed out the breather when you start the bike. This is
usually happens after the bike has been sitting for a while and is caused
by oil seeping past the oil pump check-ball .(Pre-'77XL, Pre-TwinCam
BigTwins, or the oil filter mount ball-check '87 and later XL) Often this
can be corrected by simply replacing the check-ball. In more severe cases
the check-ball seat may need to be resurfaced. Be sure to remove the pump
from the motor before lapping the seat and thoroughly clean all the lapping
compound from the pump before reinstalling.
