I have a '91 240SX, DOHC, A/T, 80,000 miles. Recently, it started making a mechanical whirring noise. It is synchronous with the engine speed, and I can feel it through the gas peddle as a high frequency vibration at some speeds.

Also, it seems there is a ticking sound from under the hood that has gotten louder (I have already removed the top chain guide and there was no change in the noise).

Any ideas? Any common 240 problems that could be causing this? I am thinking that it might be in the exhaust, but I wanted your opinion on things to check.

Thanks in advance for your help.

Houston 240 wrote:Also, it seems there is a ticking sound from under the hood that has gotten louder (I have already removed the top chain guide and there was no change in the noise).

.

You have removed the top chain guide?:eek:

Put it back on right away if you dont want chain slap.(or worse)

Fred...

This could be a bearing noise from possiblie the power steering adjuster pulley or alt. or a/c compressor pulley bearing or adjuster bearing for the a/c.Vibrations such as these can be transmitted through the accel. cable to the pedal. Try taking the belts off one at a time and see if the noise goes away. But don't run it long with the water pump belt off and keep an eye on the temp.