my lifters in my 92 cherokee 4.0l were getting pretty noisy, so a couple of weeks ago i replaced them. at the same time i replaced the pushrods, thermostat, serpintine belt and of course all the gaskets. everything runs great, but when i turn the car off, the engine proceeds to make a fast pace clicking sound, anywhere from 10 secs up to a minute long. i have no clue what it could be, but it sounds like its coming from inside the valve cover. any thoughts would be great.