the first thing to question is the blower fan. this hasd been discussed enough that almost every one has an idea how it should look. the other thing, and the thing most often the cause, is AlWAYS over looked. almost every one "thinks" that their engine is clean but most are not. open the engine up, that is to say remove all of the shields and fold the cooler over. air alonme or water alone will not get it clean. you must wash one direction and then blow then wash in the other direction and then blow. you must do this until nothing else comes out of the coolers or fins on the engine. i have seen it take an entire day and then some of washing and blowing to get clean. once it gets wet you better get it really clean or it is worse off. it will some times take a long time to get the material to loosen up and come clean. vstk