I drive a 2000 F250 5.4L. Currently has about 168,000 miles on it. I changed the oil the other day and cleaned the air filter. I used what I usually use on the oil change which has never been a problem. But this is first time to clean the K&N filter. A day or so later my engine is making a loud air rushing noise. Under throttle the engine compartment sounds like a wind tunnel. At 3500ish rpms it makes a harsh whistle noise. The air rushing noise doesn't go away once its warmed up or after the engine has been cool. Noise didn't go away with the filter being taken off either.

Could all of this be caused by cleaning and not using k&n air filter oil (but rather WD40 upon Dad's suggestion)? Or is there something else going on?

Any help is greatly appreciated.

 

WD40 is not equivalent to air filter oil. Air filter oil is thicker and stickier. Do you still have the OEM airbox? The K&N setup is really of no benefit IMO. It doesn't filter as well as a stock setup either.

Dare I ask what you used to clean it with and how long did you let it dry before reinstalling it?

It doesn't matter anyway, get the correct oil or return it to stock condition. That filter isn't filtering much of anything at this point.

 

I cleaned it with dawn and water. Let it sit in the Texas 100 degree sun for a few hours to dry. I still have the OEM airbox somewhere. Do you know of any common local places that stock the oil without having to order it?

 

Autozone, advance, oreilys? Not sure what you have in Texas.

 

I'd put a stock filter back in before the K&N however.

 

I found an advance that has some oil in stock. If that doesn't work I'll try putting in the stock Ford setup.

 

Cleaned the K&N air filter with the right cleaner and oiled using the right oil. No difference.

On a hunch I popped the hood of our f150 (same size engine) and spun the fan..moved pretty well..went to spin mine...the fan clutch is so tight that I could turn over the engine when trying to move it.

So I shall start on the fan clutch tonight.

 

You are probably hearing the fan, but regardless I would put the stock filter back on. I had the K&N and ditched it after it fouled up my MAF sensor the first time. I see no noticeable power increase or fuel mileage difference with the K&N.

Clean the MAF as well cause it could be covered in oil as well. Only use a MAF cleaner or electrical cleaner on the sensor because it can be damaged easily. If you checked the fan clutch on your truck while it was hot the clutch may have been locked up so there may not be a problem there.

I am not sure what a fouled MAF sensor will do other than make my truck run like a bucket of turds, but it could be that your truck is running rich and getting hot quick since the MAF is fouled. If that is the case the fan clutch will lock up and try and cool the radiator down. Just a thought.

 

The K&N has never caused me problems and I noticed an increase in power and gas mileage (Verified with numbers). I cleaned the MAF the other day with electric cleaner but it really wasn't dirty so no change. Today I changed the fan clutch and that was the problem. Turns out the bearing noise I heard a week ago (and forgot about) was a fan clutch bearing that came loose and then lodged in the clutch somewhere and locked it up. Swapped out the old clutch for a new one and the noise is gone. Thanks for the help though.