1989 240sx Rattle??

[Krazy91]

Ok I just purchased a 89 240sx it's in good shape well maintained its Auto :thumbd. Has 200K on it but it's Canada so thats Kilometers but the engine looks good and doesn't shake or run rough. Anyways it starts and idles perfect but when its rev'd up the engine makes a rattling noise higher it's rev'd the worse it gets. I know this is a pretty vague description. But any ideas?

Thanks (got this site from buud off another site)

[projectsr]

the best thing I can tell ya is the sohc ka24e timing chain gets loose at times. Many people have had problems with that including me. Or Valves could be tapping pistons. Get rid of that motor.

[drjohn]

Timing chain could be the problem but this usually goes away when you add RPM to the engine because the oil pressure controls the chain tension. It doesn't sound as if the valves are damaged {bent} do to the good idle. I'd check the oil pressure first. This can be done at the oil sending unit. With the engine hot it should be 10 psi at idle and at 2800-3200 rpm it should be around 60-70 psi. If the pressure is good you can remove 1 plug wire at a time when it's running, US INSULATED pliers, and try to see which cyl. is the quitest. This can tell you if you have a bad piston or a worn bearing in the cyl. with the least noise. As always when in doubt take it to a good shop to be checked.

[Nismo1182]

I recently purchased my 90 Coupe. Yesterday i noticed a strange ticking sound, like metal against metal. I drove around a bit (15 minutes) and the noise got louder with rpm. Then i went back home and went out again 15 minutes later and the noise was gone. The noise is loud enough that i can hear it inside the car with the windows up and i can hear it a bit with my radio on. Would this also be the timing chain or something else? The guy i bought the car from said he had the timing chain replaced not too long ago.

[drjohn]

That type of noise is more to be a lifter that is loosing it's prime. That is the reason that it comes and goes. You can try running a qt. of Amsoil atf in the oil for about 20-30 min. at idle before your next oil change and it might flush it out. I've had pretty good luck with it. It cleans the lifters out. Do it before the next oil change so you don't leave it in.

[Nismo1182]

That type of noise is more to be a lifter that is loosing it's prime. That is the reason that it comes and goes. You can try running a qt. of Amsoil atf in the oil for about 20-30 min. at idle before your next oil change and it might flush it out. I've had pretty good luck with it. It cleans the lifters out. Do it before the next oil change so you don't leave it in.

Automatic transmission fluid? Would that work better than a motor flush someone else recomended or would it be about the same?

[drjohn]

Amsoil has additives that help to loosen up rubber seals and clean and ludricate at the same time. Sometimes if you use a engine flush it will remove large amounts of trash in the engine which go in the pan and can clog the oil pickup and starve the engine for oil and damage bearings.

[Nismo1182]

Doh, I went ahead and did the engine flush before i saw your reply. But the engine is coming out soon anyway for a clutch install and to replace hoses and other little things. I'll do the amsoil thing before i remove the engine.