hey my names gutchi and i have a 1989 240sx coupe. my 240sx has 50k miles on it, my car recently has been giving me problems. i was racing a honda integra typeR when going 65 miles and droped the clutch into third gear i red lined evey gear to fifth going 115mph and slowed down when i heard a tappin noise in motor. i think its a valve thats stuck. i have used sea foam and made it worse. if anybody could give me some info on it that be tite.....................

 

hey man the tappin noise you here is it always there or like only areound 3000and if it is only there rev it up to 4500-5000 does it still make it??? if its only around 3 your paoblem may be you lifters the 240s have hydrolic valve lifters sometimes they blow a leak pull your valve cover of pull off the rocker arms and squeez each lifter if one moves then thats your problem they about 50 bucks a piece. they went on my car i had to replace them. tell me what you find out i will try and help out...my cars motor is sitting on a bench right now with some big problems lol so i can look at anything for ya lol.

 

could be a rod bearing.

 

Does it make the tapping noise at all when you stop and idle?

 

Its your valves for sure, your probably floated it and one got a litttle bent. Take care of it now before it breaks off and goes into your cylinder and messes everything up.

 

If a valve was bent the motor would run like **** if it even started.

 

I had a bent valve for 1 month before it even broke off. It started fine sometimes it ticked real bad and sometimes it was real quite. Its his valves. If it was his "rod bearings" it would knock istead of tic.

 

what it is i can't say for sure.

what i can tell you is that most if not all nissan engines are interference engines. so a bent valve can cause major damage, get it fixed asap.

to find out if it's a valve do a leak down test.