From time to time, a rattle through the front with the engine doesn’t always necessarily mean the VCT gear is worn out. The timing chain guide to the SR20 and KA24 engines is known to loosen and rattle, knocking over the valve protect since the timing chain moves beneath it. https://beaujihec.blogofchange.com/32532231/the-basic-principles-of-jdm-nissan-sr20-turbo-engine-for-sale