BMWMOA 162849 | BMWRA 41335 | VROC 8109-R | VBA 19
Since the problem is not yet resolved I want to go back to basics for a moment. Oil that seeps or leaks out of an engine seldom smells like "burned" oil unless one of two things happens:
1. It gets on something very hot like the exhaust header, catalytic converter, or muffler.
2. Is getting into the combustion chamber and being smelled in the exhaust.
We have nominations for leaking seals and for oil in the airbox. One would eventually appear external to the engine while the other could first appear in the combustion chamber and exhaust.
I think the next step in the process is to try to determine whether the smell is oil on hot engine parts or oil being burned in the combustion chamber.
My tried and true method for finding oil leaks is to use white antiperspirant spray powder or spray-type baby powder. I spray it on thoroughly cleaned parts where an external leak is suspect. The white powder sticks to the parts and engine oil will quickly produce a brown stain. If it is a slight leak or seep the stain spreads out from the point of origin, leaving a little arrow shaped brown spot pointing at the source of the oil.
It would be perfect except for the "thoroughly cleaned" part. I would have passed that right by, except I just happened to be looking under my bike earlier today...
Well, it's a bit cleaner on one side ... The other is a bit inaccessible until the baseboard is installed and the Las Vegas, Carmel, SF vacation is over.
I used a paper towel spot sprayed with WD-40 to clean the bottom of the sump area. What would you have used?
2011 R1200RT Thunder Gray Metallic; 2000 Triumph 900(sold)
Thanks again for all your expertise. After removing 6 oz. of engine oil the odor continues. I went over the exhaust front to back again finding no signs whatsoever of oil burning off the exhaust parts. I also went over the engine and find nothing indicating a weep/leak. I will take the steps you suggest using baby powder to help find a source.
You note in #2: (oil) Is getting into the combustion chamber and being smelled in the exhaust. This may be a silly question, how does this happen? Or can you explain how this happens?
You can loosen the clamps on the air tubes and slide them into the air box. Then take a clean cloth and rub it on the inside of the air tubes. Ditto on the air bores of the throttle bodies. Any oiliness would tell me there is oil in the air box being picked up by the intake air stream.
Beyond that we enter the realm of engine mechanical condition. The two prime spots for oil in the combustion chamber is past intake valve stems, or past rings.
I'd check the air box air stream first. Then a compression test and leakdown test could be in order.
The issues are not toally isolated. Oil in the air box accumulates from the crankcase vent. This is exaserbated when there is excessive blowby past the rings, but oil can condense in the airbox just from normal crankcase venting, and it can build up over time.
Also the amount of oil that might collect in the airbox is related to excessive oil in the crankcase air - if the engine oil level is too high.
I just went out and removed the painted plastic parts to gain access to the air "snorkel" tube, and air filter, which were removed. I examined both tubes for any obvious signs of oil using a paper towel attached to forceps and found nothing. Would one expect to see oil dampness on the paper towel or would it be more of a filming?
The bike just turned 7.5K miles and runs outstanding????
Since you have the plastic off I'd go one step further. Loosen the air tubes (black plastic) between the air box and the rear side of the throttle bodies. There is a clamp at the air box end and at the TB end. Wiggle-wiggle them rearward a bit and check the inside surfaces.
If these are essentially dry I would ride the thing until some obvious source of the odor becomes apparent.
It is entirely possible that what you smell is in fact in the exhaust from the combustion chamber. At that low mileage the bike is not fully broken in and some oiling past the rings is more likely than not.
It's not as easy to remove the intake tubes on the hexhead/camhead engines as on oilhead engines. Instead of screw clamps BMW used a type of reusable CV joint clamp that requires a special tool to remove and replace it. I found one of the tools on Amazon for about $15 or so.. it's made by Lisle (same one the BMW dealer had actually.)
The rubber tubes - unlike the oilhead tubes - do not extend into the airbox, there is a tube cast into the airbox that it connects to.
It is quite possible he has some oil in the airbox. Unlike earlier bikes, there is no oil drain in the airbox. I suspect BMW thought the crankcase vent would suffice for that purpose.. it comes off the left (port) forward corner of the airbox and goes straight down to the left side cylinder head. But - I have seen oil buildup in the airbox if the engine is overfilled. The bottom of these airboxes is molded to closely match the contours of the transmission.. meaning there are hills and valleys in the bottom. The valleys can fill with oil which won't drain back unless you lay the bike on it's side. I had what appeared to be a transmission output seal leak on my bike - that ended up being oil seeping out of the airbox and running back along the top of the transmission, dripping eventually down on the forward edge of the front swingarm boot. Sopping up the oil with a rag on a stick through the air-filter opening "cured" the leak.
It's possible his is leaking/seeping at some other airbox joint that isn't really visible and eventually ending up down on the exhaust. I'd suggest that he find someone with a borescope and take a good look at the inside/bottom of the airbox. That's how I found the oil in mine (Harbor Freight borescope works just great for this sort of thing.. bought it for the Porsche, used it for lots of other things now.. was on sale for $89.)