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Oil in air box

3.8K views 4 replies 2 participants last post by  Footy  
#1 ·
I have recently purchased a low hour 1 owner 2007 TRX450ER. So far I like it a lot. After my first long trail ride I noticed some oil in the intake boot as well as on the filter. Upon closer inspection I determined the oil is motor oil and not air filter oil. I did see some evidence that this was coming in from the CCV. This quad seems to have plenty of power and I have not noticed any smoke from the exhaust so I do not think this is coming from worn piston rings. It starts and runs perfectly. According to the seller it still has the original chain and sprockets as well as brake pads so I tend to believe that the hours are indeed low. Very little boot wear on the frame or on the engine covers. So what issues could cause this oil in the air box? I did changed the oil before riding it and refilled with the exact amount specified by the manual (690mL).
 
Discussion starter · #4 ·
The transmission vent hose was not in the circled area but it was not attached to any other place either . It was just there but not connected to anything. The search for the oil source continues.
 
Discussion starter · #5 ·
Today I checked both engine vents and the transmission vent hose for blockages. All 3 of these are flowing freely. I also checked the hose running from the "T" to the airbox. It is clear as well. I believe the oil is traveling up the lower engine vent hose (CCV) and from there to the airbox, I was wondering if standing the quad up on the grab bar would cause oil to travel through the lower vent hose and into the airbox. I had the quad standing up while washing it.