I tore apart my engine and replaced my oil pump. But when iput it back together there was a very loud noise that sounded like it was coming from the lifters. At first i thought it might be PTV but i took it all apart and timed it again. I just torn it apart yet again and can't see anything wrong. I have good oil pressure and the lifters are all full of oil. When i replaced the pump i didn't touch anything in the heads just the front of the engine. Does anybody know what the noise could be. Thanks a lot for any info.