Oil Leaks FAQ
compiled & edited by Kristian #562
Edited by Winter, 29 December 2005
Please read the Disclaimer before
attempting any work in this FAQ.
29 December 2005
From time to time your bike may develop oil leaks. It is a good idea to
Clean your bike on a regular basis, as this
may sometimes help you identify the source of oil leaks. As a general
rule, if you have an oil leak, check any bolts that normally holt that
part together - make sure they are all torqued to spec. If it is coming
from a gasket of some sort, you may need to replace the gasket.
What are the Most Common Sources of Oil leaks?
by Flash #412, Kristian #562 & HsN
Well...Generally, but not in any order of frequency of occurrence, they
- The Oil
Filter Cover Plate O-Ring. Either the Large O-ring may have been
nipped during an Oil Change or more likely, if you didn't do it yourself,
someone tightened up the Filter Cover without checking that the little
black ignition wire that runs JUST beneath the Cover down to the
Alternator was not kept out of the way and it got stuck under the Oil
Filter Cover Plate. Refer the Classic Oil
Change Chain FAQ or the Oil Change FAQ
for the GS for further details.
- From the Oil Pressure
Sensor. See the Oil Pressure
- From the Sump
Plug. You may have stripped it. See the
Sump Plug FAQ.
- From the Airbox
via a Circuitous Route. See the Air
Filter FAQ and the GS
Air Filter FAQ.
- From the Countershaft Seal. See the
Counter Shaft Seal FAQ.
- From the Gear
Shift Lever Seal. Replacement when on the bike follows the same
procedure as the Counter Shaft Seal
FAQ. Off the bike see the Water
Pump FAQ or the Clutch FAQ.
- From a
Gasket. See the Head Gasket
- From a
Broken Oil Tank (GS/Dakar only).
It could just be some remaining waste oil from the previous oil change,
try to clean everything and check if some new oil come off again.
- Q. Ok, there
also was some oil leakage near the bottom of the engine, I was never quite
sure if that was from the chain though (I bought the bike used). Dealer calls
later in the afternoon to tell me it's the base gasket, meaning they have
to order parts (~2 days) and then take the engine apart. Has anyone else have a
base gasket fail? What is the cause for that? Bad parts or assembly at the
factory? Abuse by the previous owner? This is all fixed under warranty, and the
dealer was nice enough to offer the loaner while they're waiting for the parts
and then apply some of the warranty work hours to the service as well.
A. I had the same oil leak at about 4k miles or so. My tech thought
he would have to replace the gasket but it turned out that the engine bolts were
not torqued to spec. Loosened during riding? I don't know. Anyway, he tightened
them to spec and the leak was gone. No problems since. Rebecca.
- There have been a couple of reported cases of leaks from around
the RHS engine cover (where the magnito is), including the bolt just below
the two bottom oil filter bolts. In my case some of the bolts were loose
enough for me to unscrew by hand! Torque them all back to spec. If that
fails to stop the leak, you may need to replace the gasket (not sure if
this is the same as the base gasket already mentioned. Winter
#1935 with input from Sean Mason
Unknown Sources of Oil Leaks
i.e. No Feedback on the ACTUAL problem. If you recognise the
Symptoms, please let us know YOUR Solution.
- Just thought that I add myself to many F650GS owners out there
who have oil leaks. Mine's a new 2002 GS with 1,000 miles on it. I had the
600 mile service on it and rode it for a week. I left it in my garage for
a week while I was away on business and upon my return, I notice oil on
the floor right under the engine. I'm taking it to the dealer this
weekend. I hope to have it fixed quickly. Ed Northern VA
- I had my 02 Dakar serviced last month and seem to have developed a
small oil leak from the sump plug. At first I thought it was residue from
the newly fitted Scottoiler, but it's definitely engine oil. It's only a
small amount and the oil level in the sight glass is on max. I am going to
speak to my dealer again though to get him to check it out. I looked at
the FAQ's on this and they talk about a stripped thread etc. Would this
problem be consistent with that diagnosis do you think or something more
- My bike is leaking oil near the oil tank on the left side of the
faux tank. I just took it in for the 1000km service on Monday and today is
the first time I've ridden the bike since. I discovered a small pool of
oil around the left leg of the centerstand and found that the oil has been
running down the left spar of the frame from underneath the tank. Could
the oil tank be broken, or is it leaking because the dealer overfilled the
oil? the oil level is past the the top of the red sight glass when the
engine is at running temperature. I'll plan to call the dealer in the
morning but I thought I'd check the board to see if anyone has had a
similar experience. hk_rider
Whitish Material Under the Oil Filler Cap?
Problem: Over the last month I've been noticing a white foamy
goo on the inside of my oil cap- unscrew black cap, flip over, see white
goo. I was wondering if anyone else experienced the same thing. The
Mechanic at my shop had something close to cottage cheese on his, and
there is no foam in the oil tank itself on either bike so I'm sure it's
not a coolant leak. His guess was condensation in the tank. 5W30 - light
white foam - avg riding temp 30F 2001 F650GS 4500 miles.
- Condensation - Don't Worry About it. It's probably this.
- Failed Water Pump - Worry About it. Check your Coolant Level is
NOT going down and your Oil Level is NOT going up and that you have no
Weephole leaks. See the Water
Pump Seal Repair FAQ for details
- It's an oil/water emulsion. Your oil collects various combustion
by-products. The "mayo" indicates that your motor isn't getting
hot enough to drive this moisture out of your oil. If your bike is a GS
with separate oil tank, it probably exacerbates the problem. Harl #380
- The old Airhead bikes had this problem during winter when the
weather was cold and damp. They have very large aluminum engine cases and
it was almost impossible to get them hot enough during the winter to cook
off the moisture that condenses into the oil inside the engine when it
cools. All you can do is wipe the gunk off of the cap and change your oil
more often during the winter. If it was me, I would use cheap
"dino" oil and change the oil every 2000 miles, or every 3
months, during the winter. (To save money, I would just change the oil and
not the filter. I would change the filter at 6000 mile intervals).
- Water is one of the by-products of combustion. Which doesn't
include the amount of moisture (even at 7%) that is in the HUGE amount of
air required by an internal combustion engine. Some will get past the
rings. As the hot gasses in the crankcase (and cylinder, if the bike stops
with an exhaust valve partly open) contract as they cool, they suck in
ambient air (7% humidity) which will condense on the metal parts, when
cold. Good news, the oil is designed to deal with a certain level of
water content. The plastic oil cap may stay cool enough in cold weather to
condense oil/water vapors together (yielding the white emulsion you see).
Marty #436-Chicago-97 F650F
- Oil Sludgy Stuff. I changed the oil this weekend (along with valve
adjustment X2, water pump, spark plugs/caps, coolant). it's been about 8+
months, about 4000 miles (twice what I normally do, been a slow year for
miles with all the shop time). I always use BMW full synthetic, changing
at 2K mile intervals. please no comments on the pathetic mileage this year
(I put 19K miles on the bike in two years, then only 4K the last year...).
When I removed the frame plug, the oil just trickled out, like there was
blockage. so I stuck a pointy thing in the hole and the oil began to gush
out, along with a bunch of other crap. some sort of oil sludge/build-up
had stopped up the drain. the stuff was flaky-looking, and looked almost
metallic, but when rubbed between fingers, it slowly disintegrated and was
gooey. there was no metal in it. So I took out my frame oil screen and it
too was covered in this stuff. I think it slowed down the oil flow back
into the sump, making measurements read high, even after waiting one
to two minutes (I noticed this recently). Anyway, I used carb cleaner to
get out as much of the crap from the frame tank as possible, then ran two
quarts of oil through it to "rinse" it. lots of crap came out.
Then I drained the sump and was pleasantly surprised that it was totally
clean, all the stuff had been trapped in the frame oil screen and oil
filter (filter looked clean though). The only thing I can think is that
the bottom of the frame tank is so close to the header pipe that the
"old" oil got cooked. but I can't imagine it gets that hot.
I'll change oil again in a few weeks to see what it looks like, and more
regularly after that. well, I found the problem with my bike, I think. I
changed the oil this weekend. it's been about 8+ months, about 4000 miles
(twice what I normally do, been a slow year for miles with all the shop
time). I always use BMW full synthetic. when I removed the frame plug, the
oil just trickled out, like there was blockage. I stuck a pointy thing in
the hole and the oil began to gush out, along with a bunch of other crap.
some sort of oil sludge/build-up had stopped up the drain. the stuff was
flaky, and looked almost metallic, but when rubbed between fingers, it
slowly disintegrated and was gooey. so I took out my frame oil screen and
it too was covered in this stuff. my theory is that it slowed down the oil
flow back into the sump, making measurements read high, even after waiting
one to two minutes. I used carb cleaner to get out as much of the crap
from the frame tank as possible, then ran two quarts of oil through it to
"rinse" it out. lots of crap came out. Then I drained the sump
and was pleasantly surprised that it was totally clean, all the stuff had
been trapped in the frame oil screen and filter (filter looked clean too).
the only thing I can think is that the bottom of the frame tank is so
close to the header pipe that the "old" oil got cooked. anyway,
check your frame screen the next time you change oil. mark #403
- Oil sludgy stuff. Carbon from cooked bearings looks like that.
They get hot, oil starts burning on the bearing surfaces, if you don't
actually seize and it cools down again, friction and fresh oil washes it
away in flakes. It tends to do a great job of blocking oil ways, I'd
suggest getting some cheap oil 30/40, doing a change, running for a while,
changing the oil again until you can be reasonably sure you've flushed the
seen "flaky" sludge, but the typical stuff is caused by oxidation by-products of
the oil (they become insoluble in the oil and "settle out"). The oxidation rate
is increased by nitrous/sulfuric acid (exhaust blowby) combined with water
Vapor, catalyzed by (wear) metals. Once the "precursors" have formed, the oil
will slowly turn to sludge with NO further mileage. That's why it's best to
store the bike (winter or otherwise) with a fresh change of oil that still has a
full charge of anti-oxidants. The old saw about changing your oil 3 months or
3,000 miles does have a grain of truth to it (but today's oils are better). That
said, severe service (lots of short trips that don't get the bike warm enough to
vaporize condensation in the crankcase) is hard on the oil. The frequent cold
start-ups can create more wear (i.e. higher loading of metal wear particles).
Bottom line is to change the oil at least twice a year if you ride it at all.
Marty #436-Chicago-97 F650F
I take it that the frame tank was fully drained thru the frame drain hole the
previous oil change?--
A. yes, always. would be kind of messy through the frame filter hole,
don't you think? :-)
Q. What brand of oil?
A. BMW full synthetic, 15-50W, $108/case (ouch!)
Q. Is it possible that your oil was contaminated with water? Or coolant?
A. Seems unlikely, but I was thinking the same thing. But when I changed
the water pump and coolant, immediately following the oil change, the reservoir
and radiator were both full. And the water pump shaft was BARELY worn at all on
the water seal side
Q. Have you inspected the exterior of the old oil filter
A. Yes, when I changed it. Looked clean. Dark brown, but free of debris.
Q. Is it possible someone maliciously dumped crud in your frame
tank when it was parked somewhere?--
A. Possible, but again unlikely. Most of my parking is at work
(w/security) or in my garage. And I have a temp dipstick that I always have
perfectly adjusted so that the 200F mark is at 12 o'clock. If someone had
removed it and replaced it, they would have had to take care to put it back
Conclusion: In another type of engine, with major bearings being
made of babbit material, I'd WAG that the crud was babbit from a failing
bearing, which can sometimes precipitate out due to water contamination,
but I don't think so in this case. It's also possible to have the
precipitate analysed to see what it's made of. Well, I don't know about
analyzing it, but I'll at least talk to the dealer about it. But first,
I'm going to have them look at what appears to be a leaky (barely) head
gasket. I've got a bit of oil coming out the front between the head and
cylinder, close to the exhaust. I have two months of warranty left, and I
don't want to try to explain why I didn't change my oil for eight months
when they're looking at a (somewhat) oil-related problem. Once that's
taken care of, I have a paper towel that I strained some of the sludgy
stuff through, saved in a zip lock. I'll ask about it after the warranty
work, see if they've ever noticed anything like it when they've done oil
changes. Beyond that, I'll just change my oil more frequently (and ride
more). Mark #403
- I asked
about draining the tank thru the drain hole as there is quite a large space for
stuff to collect between the drain hole and the intake screen, and actually, I
DO sometimes change my oil out the top filler. Not that I'm so strong I can flip
the bike over tho! :-) I have a vacuum oil change system that I use for some
marine engines and generators where I cannot access the oil drains, so when I
want a quick messless oil refreshing, I use a special small tube to go down
inside to within 1" of the drain hole and suck out 1.5-1.75 quarts out the top.
Is the dried residue gritty? Please save it! The head gasket leak might be a
clue. Or not. Flask/Kristian, are any of the top end gasket set composite/filled
gaskets? As in, some sort of filler sandwiched between 2 sheets of metal foil?
- I'll ask
them to look at the gasket carefully when they remove it. I dropped the bike off
today at the dealer for a new VR (probably), and to replace the dash (cracked
light lens), and look at the leaky gasket. since i need the bike back today
before a short vacation, i only expect the VR to get done. when I take it back
in a couple weeks, I'll ask to see the old gasket. So far, that theory seems to
make the most sense. Mark #403