I got my motor back into my car and running last week. Everything seems to be working nicely other than a strange whistle/whine I seem to be hearing when the motor idles that I did not have while on the dyno. The noise seems to be a whistle or a whine not a grinding, scraping, or growling noise. I made a post last week thinking it was the alternator. Well that ended up not being the source of the noise at all. So far I have disconnected my power steering pump, water pump, and alternator, taken off the air cleaner, removed the breathers, removed my tach drive cable, pushed in and out on the clutch pedal, listened underneath the car, plugged all vacuum lines, and still no clue as to where this strange whistle/whine is coming from!!! The noise just does not seem to be coming from one particular area or spot and you hear it mainly at idle. If I give it a little gas to get the motor off idle the noise slowly fades away. Today I pulled the oil filter off and cut it open and the filter is nice and clean. Motor holds great oil pressure when idling and when running and temp stays right around 190. The only things that are different now that the motor is back in the car are I have a new clutch, pressure plate, throw out bearing, and pilot bearing installed. I did also rebuild my tranny while the motor was out but the noise occurs with the car sitting in neutral with or without the clutch engaged. Anyone have any ideas of what I might look for or a better way to trouble shoot something like this?

 

Run it with the air cleaner off , if its a whistle it could be that.

Todd

 

Sounds like it could be a vacuum leak, perhaps around the base of the carb or intake manifold.

 

Check your pcv, remove it plug vacuum hose. I had a whistling pcv valve once took me 3 months to find it. I just happened to replace it because it was old but was working ok, whistling noise went away i was shocked that it was the pcv, good luck i hope that's it. Oh buy the way i have a noise also with my 69 350/350 running at idle hood closed standing in front of the car i here this lightly sounding whine, you can barely hear it, but that's all you can here. Yes its the delco alternator and no you cant hear the motor just the alt how cool is that 68000 miles darn delco alternator.

 

Thanks for the ideas! I disconnected and plugged the vacuum port on the intake and also removed the PCV and beather. Still same noise. I'm going to have to get out in the garage again once it cools down!!!! 95 degrees today with 108 heat index!!!!! To nasty for me right now!!!!

 

Did you use an aftermarket all-metal timing chain set, particularly a double-roller one? They can be noisier than the standard factory set. Sometimes a high volume oil pump can transmit noise back through the distributor shaft, especially if the shaft bearings are not in good shape. Use a mechanic's stethoscope (cheap but effective ones available at local auto parts stores) and try to determine the source of the sound. Cam bearings installed incorrectly can result in a dry cam journal and noise. Lots of things to check. Good luck!

 

I did use a Manley steel double roller timing chain set and I'm using a Melling oil pump. The thing that has me wondering where this noise is coming from is that I did not hear the noise when the motor was on the dyno. I started hearing the noise once I had the motor back in the car and got it running. I will try to track down a automotive stethoscope and see if I can track it down. Thanks for the help and ideas!!

 

The worst noise I ever heard in my Vette came from the passenger seat... I replaced her and the problem went away.