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

Introduction
What are the Most Common Sources of Oil leaks?
Unknown Sources of Oil Leaks
Whitish Sludgy Material Under the Oil Filler Cap?

Introduction

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 are:

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 Sensor FAQ.
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 Weeping Head Gasket. See the Head Gasket Replacement FAQ.
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 serious? Dave
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.

Short Answer:

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

Feedback:

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). Richard #230
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 system. Pete
Never 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
Q. 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 exactly right.

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? Todd#389
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