'87 911 3.2 Targa (engine noise?)

[newjerseydave]

My '87 911 Targa has 95k miles and has run great to this point. Still running great (starting fine, pulling strong, etc...) but a weird engine noise has developed after it's been running for 5-10 minutes. The underlying engine noise is the same (again, sounds good, very smooth) but it now sounds like a "compressor" is also running. Hard to describe though....... like a whirring noise.

Any ideas? thanks, Dave

[CCM911]

Alternator bearings going bad? Hard to tell from your description.

[JRSIII]

Is this at idle or running down road? If at idle in garage, is it possible it's warming up to the point that the engine compartment heater blower, which also provides supplemental engine cooling at a certain temp, is kicking on?

[Franks89-911]

Any way to record the sound and post it? Video or WAV file?

[newjerseydave]

Running down the road. I don't let the car idle for more than 20-30 seconds then start driving.

[newjerseydave]

link to video

https://youtu.be/qS9t-P_lK_A

[Franks89-911]

I didn't hear anything that unusual, actually sounded good, but maybe that's just my untrained ear. Could be your a/c compressor? Maybe take off the a/c belt, run the engine again and see if sound replicates?

[dyerkes]

Likewise, it certainly sounds normal, so following Frank's suggestion you could test unplugging the blower motor that JRSIII referred to and see if there is any noticeable change. Good luck!

[newjerseydave]

Is there an easy way to unplug/disconnect the blower motor?

And even thought AC compressor is relatively new, I've never used the AC.

[Uncle Enzo]

To isolate the alternator run it for just a brief moment with the belt off.

[wrxnofx]

Originally Posted by newjerseydave

Is there an easy way to unplug/disconnect the blower motor?

And even thought AC compressor is relatively new, I've never used the AC.

Just put your hand on it. You'll feel it if it's running. That being said, it's a single 2 pole connector in the back of the heater blower motor if you want to disconnect it.

[dyerkes]

Yes, there is a white 2-prong connector that runs into the electrical motor. You just need to get a flashlight and look at wires running into the back left hand side of the motor. I suppose there might be a fuse you could pull, but I am not sure what else is depending on that fuse.

[DRACO A5OG]

Originally Posted by Uncle Enzo

To isolate the alternator run it for just a brief moment with the belt off.

+1.

I do hear what sounds like a bearing when you shifted to the side.

[newjerseydave]

meaning like an alternator bearing?

[darrin]

another question, does the noise change/dissipate if you depress the clutch? I.e. is the noise engine or transmission-related?

[newjerseydave]

no, once it begins (and again not very loud but continuous), it is steady at a stop or moving