Oil in Airbox- is this a common problem?

wera688

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How many people have found oil in their airbox? I have found oil regularly in my airbox over the miles (199,000) of my 2014. Sometimes just a little, other times quite a bit. Longhaul Paul showed me a picture once of a small lake of oil in his airbox. I have heard of others also. Is this a 'common issue' on the Super Tenere? I ask because my engine has stopped running due to low/no engine compression and we believe it is because of extremely dirty valves. fyi- I make sure the oil level is correct when I perform oil/filter changes.

Curious, maybe there is a slight engineering design problem allowing or contributing to excessive engine oil blow by? I'm thinking of routing the breather tube out of the airbox with a filter attached to the end...if I can get it running again.

Kith
 

Boris

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My bike has only done about 35k miles and each time I’ve opened the air box (5 or 6), there has been oil in there. Not a lot, but it’s certainly there. Not a puddle, but more than a film.
 

RCinNC

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Same experience for me. Mine has a bit over 76,000 miles on it, and I've found oil in the airbox when I've done filter changes. I wouldn't characterize it as a lot, but it was there.
 

Longdog Cymru

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I think you may find that the engine breather may exhaust into the inlet/air box area to burn off oil vapour and it is inevitable that some oil mist will condense producing the oily puddle.
 

EricV

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Gen I bikes were more prone to this than Gen II bikes. After I saw the oil/carbon build up on my valves at 83k when my '12 had it's CCT failure, I started using Yamaha Ring Free with most fill ups and while the oil in the air box continued, the valves were cleaner. On both Gens, prolonged high rpm running tends to create more oil blow by and that type of rider will more likely find oil in the air box. In Paul's case, he never had the valves checked/adjusted and likely that was a factor on his as well.

You put on the miles. Have you been doing the maintenance? I had some contact with another ~200k Gen II rider a couple of months ago who's bike stopped running and wouldn't start. I don't know the outcome, but after some conversations, he had never had the valves checked/re-shimmed and in his case, I strongly suspected a CCT failure since he also never replaced the original CCT. Even on the improved Gen II design, the CCT should be replaced every 100k or so as a preventative measure. It's a LOOOONG cam chain. It does not tolerate excess play as well as a shorter one on an inline four. Add that it's oil pressure assisted and it's most common for it to fail on the first start up after an oil change when you don't have full oil pressure for a few moments longer than on a normal start up.

Good luck, I hope it proves to be a more basic repair.
 

wera688

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I had some contact with another ~200k Gen II rider a couple of months ago who's bike stopped running and wouldn't start.
yes, that was me. The exhaust valves were only a little tight. CCT is ok, timing is ok, valves move freely and have been adjusted and still little to no compression. There is no fuel or metal materiel in the oil sample, thus normal compared to past samples. Nothing has been found to be broke.
I believe the oil/vapor buildup after many miles affects the head and valves. There is 'goop' / blowby oil? in the cylinders at the top. I believe the compression isn't building because of the dirty valves caused by breather oil.

I dont think its a basic repair so I just purchased a lightly used 2016 and will use the 2014 as a parts bike.
 

elricfate

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I had a mix of oil in my airbox - a little from the engine, a little from the oiled filter the previous owner installed and slightly over-oiled (easy mistake to make). I'm at 27k miles (I think? I'd have to doublecheck) and I expected it. It shouldn't become an issue if you're cleaning your airbox/checking your filter at every oil change from everything I have ever read on the phenomena
 

lund

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Motor oil collection in an air intake is completely normal. ALL combustion engine do it right from new.
The reason you will see it on a motorcycle such as your S10 is because of the close proximity the air filter is to the throttle bodies and the engine block vent tube.
Even your car does it and the reason you don't see it is because today 99.99% of vehicles have their air filter mounted remotely away from the throttle body or bodies.

The oil comes from the engine block pressure build and it is routed back to the intake circuit of the motor and burned through combustion. This is called a closed loop system.
In the early days motors vented into the atmosphere via a hose and pipe hanging low but times have changed.

You should not be concern unless you start collecting more then a couple cap full of oil between oil changes.
 

Sierra1

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. . . . On both Gens, prolonged high rpm running tends to create more oil blow by and that type of rider will more likely find oil in the air box. . . .
The KLR gets t-h-i-r-s-t-y when the rpms stay on the high side, and the airbox did get a little nasty.


Motor oil collection in an air intake is completely normal. ALL combustion engine do it right from new.
The reason you will see it on a motorcycle such as your S10 is because of the close proximity the air filter is to the throttle bodies and the engine block vent tube.
Even your car does it and the reason you don't see it is because today 99.99% of vehicles have their air filter mounted remotely away from the throttle body or bodies. . . . .
My Jeep's 242ci I-6 would have a drop or two of oil in the air box, every-so-often, which was close to the TB. But, I also tended to get the rpms higher than the motor liked.
 

WJBertrand

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The oil comes from the engine block pressure build and it is routed back to the intake circuit of the motor and burned through combustion. This is called a closed loop system.
In the early days motors vented into the atmosphere via a hose and pipe hanging low but times have changed.

You should not be concern unless you start collecting more then a couple cap full of oil between oil changes.
My old Norton used to have a hose that ran from the crankcase up under the seat and then all the way to the back of the bike following the fender. not unusual to see a couple drops of oil drip there after a high speed (freeway) run. The crankcase pressure is caused by the movement of the pistons displacing air and from blow by gas that bypasses the piston rings. There is oil aerosol suspended in the displaced air and blow by gas. A really worn out engine can have a lot of blow by and really pump oil out the breather to the point you have to add oil to compensate. The Norton didn't really have an air box, just a pleated filter in a perforated metal can basically. No PCV requirements for bikes back then so that was the easy solution for them.
 

Niterunnr

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Just checked my filter and was shocked to find this much oil. Admittedly, the filter change is overdue. I noticed the capped drain hole is the left rear airbox; thinking of installing a longer tube for inspection/collection.
And why oh why, ten screws for the cover!!?? Two would honestly do, considering how stiff the cover is.
 

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thughes317

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Just checked my filter and was shocked to find this much oil. Admittedly, the filter change is overdue. I noticed the capped drain hole is the left rear airbox; thinking of installing a longer tube for inspection/collection.
And why oh why, ten screws for the cover!!?? Two would honestly do, considering how stiff the cover is.
Looks about right, especially if filter hasn't been serviced in quite a while.....don't lose any sleep over it.
 

lund

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Stripped the thread on about half of them and i am thinking of repairing them with helicoils.
Mayby using an electric screwdriver is not such a good idea after all.
Anyone caught in my shop using a power tool on plastic on customers unit will be canned. There is even a big sign in the shop saying so, those are the rules.
We have had to replace a lot of parts in the past because of power tools used on plastics at our cost.
The best way to fix the stripped holes is filling them using a glue gun, once harden predrill the hole to reuse the screw. The screws used on plastics are not regular screws but are specifically designed for plastics and DO NOT require any type of torque to hold, they will not unscrew and no excuse for stripping the hole. Your more likely to cause your self more head aches by trying to use helicoils.
 

Checkswrecks

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Just checked my filter and was shocked to find this much oil. Admittedly, the filter change is overdue. I noticed the capped drain hole is the left rear airbox; thinking of installing a longer tube for inspection/collection.
And why oh why, ten screws for the cover!!?? Two would honestly do, considering how stiff the cover is.
Installing a longer tube is an old mod. Put a plug in the bottom with a hose clamp or other way to drain it without having to lift the tank.
 

Niterunnr

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Anyone caught in my shop using a power tool on plastic on customers unit will be canned.
Can’t understand why they didn’t go with clips, cams, or at least machined screws for something that comes off this much. The other problem with electric screwdrivers is if you don’t start it by hand; you end up making new threads each time, weakening the hole. Maybe this is why they used ten!
 
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