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unit82

engine oil in air box

8 posts in this topic

hey i have a 08 wr450f and have noticed engine oil coming out the breather hose into my air box (lots) and was wondering if any 1 else had this problem or knows what is causing it any help would be appreciated

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You overfilled your oil, common mistake.

Make sure you remove every drain plug when draining your oil as well as the dipstick and filler cap - so as not to create a vacuum.

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thats the thing i thought i had over filled it to but when i checked the dip stick it said it was perfect level so i continued riding for about 45 mins when i stopped to check again there was alot more oil in there when checked oil level it was half empty so it seems to come out even though it was not over filled. i havent lost any power other wise she is running perfectly

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Not trying to be funny...are you using an oiled foam filter? When the bike heats up some oil can drip off the foam filter. Warm it up and let the bike sit. Not sure how you cold have two different readings if you let it settle?

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no its definatly engine oil because the engine oil is red and the filter oil is green

and there was probably 100 - 200 mls of oil in the bottom of the air box

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As mentioned above, are you sure when you drained the oil that the plug by the front of the cylinder was loosened? I can't say whether if you missed this that you would show the correct level or not, but what I noticed is that if that plug is not loose (I mean real loose or better yet off) it will leave a boatload of oil in the cases. Virtually everyone that has found oil in the airbox as either skipped this or just added too much. The manual for the '08 is almost spot on as far as quantity to add. You may go over to get the correct level on the dipstick, but it won't be more than an ounce or two from what the manual says.

And I've never cared the way the manufacturers route the oil breather into the airbox. That is dirty air back there and there is no filter on the end of the hose. I have always capped those off and routed the whole works upwards from the head or crankcase (depending on model and where the breather starts from) and put a uni filter on it. Routing up, it will still breathe, but the oil has a chance to flow back to the engine rather than downhill to the airbox where it will never get back in.

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thats the thing i thought i had over filled it to but when i checked the dip stick it said it was perfect level so i continued riding for about 45 mins when i stopped to check again there was alot more oil in there when checked oil level it was half empty so it seems to come out even though it was not over filled. i havent lost any power other wise she is running perfectly

I over filled mine when I first got it. I drained it and then added a quart, but since I forgot to remove one of the drain plugs it had an extra cup or so of oil in it but the dipstick read perfectly. After I hit a few woops, oil was pouring out of my airbox via the crankcase vent hose. Just drain\change the oil exactly as per the manual and clean out the airbox\vent hose and you should be fine. Good luck :)

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