Oil in Airbox- is this a common problem?

wera688

Active Member
Joined
Aug 29, 2016
Messages
64
Location
Newnan GA
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

Well-Known Member
Joined
Dec 21, 2013
Messages
831
Location
midlands. UK
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

Well-Known Member
Joined
Aug 30, 2014
Messages
1,759
Location
North Carolina
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

Well-Known Member
Joined
Jul 21, 2018
Messages
755
Location
Swansea, Wales, UK
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

Riding, farkling, riding...
2011 Site Supporter
2012 Site Supporter
2013 Site Supporter
2014 Site Supporter
Joined
May 22, 2011
Messages
7,869
Location
Tupelo, MS
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

Active Member
Joined
Aug 29, 2016
Messages
64
Location
Newnan GA
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

Well-Known Member
Joined
Aug 29, 2019
Messages
279
Location
Ohio
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

Member
Joined
Jul 8, 2019
Messages
66
Location
Okanagan Valley, Canada.
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

Well-Known Member
Joined
Nov 7, 2016
Messages
6,174
Location
DFW-TEXAS
. . . . 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

Ventura Highway
Joined
Jun 20, 2015
Messages
3,143
Location
Ventura, CA
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.
 
Top