my friend just bought a 89 240sx coupe i guess u would call it, the non fast back type, and i drove the car and it drives great, engine feels like it has pep 130,000 miles.

the thing is is that when the revs get to about 2500 + rpm it has a noticable knock. but when you're above 2500rpms and u let off the gas it goes away. anyone know what this could be? thanks for any help
he bought the car for 1500, body in great shape with se alloy rims

 

i took the car over to a mechanic friend of mine and he said since it only makes the noise at a higher rpm and not at idle that it's probably the lifters. overall i think he got a good deal and the car runs great. this weekend im gonna pull off some of my lifters from my dead ka and see what happens.

 

I had a similar problem when I first got my first 240. It was the lifters and all i did was change the oil. I had just bought it and i was bringing her home. When i pulled into my garage and check the fluids, the oil was only about 1/4 the way up on the measure on the dipstick. I called my friend up and asked him what he would do, he works for a large race car chassis company and owns a 1.6 litre 1987 200sx, he just said drain the oil and add some more. Fixed the problem for me.