Knocking Noise

[mo89300zx]

Hey guys I have a really bad knocking noise coming from my engine. I have not done anything yet to it. Going to ask all of you what kind of test or what I need to look for. My first guess is that one of the rods is knocking coming from a loose rocker arm. But I will take all the advice I can get. Thank you all again!!!

[evildky]

The Z31 has hydraulic lifters which when collapsed make a lot of racket and can sound a lot like a rod knock, which is a completely different problem form an actual rod knock which would be from the rod, usually they develop a knock on the bottom end of the rod not the top so if the noise sounds high in the motor it's likely a lifter, if it sounds low in the motor it's likely a bad rod bearing and is in danger of coming apart and making an exit hole. How is your oil pressure? might want to get with a mechanic that has a mechanical gauge to check the actual pressure as the stock gauge is a bit vague. a rod knock will almost always show low oil pressure. If that's the case you can rebuild or look for a donor.