I have a strange noise coming from the back end of my 92 C4 (non turbo).
The noise started yesterday.
This car had been in storage for about 15 years and I recently got it running. The noise appears to have started after the following service work I performed:
Replacement of distributor belt/installation of vent kit.
Change of oil/filter
New spark plugs
Setting valves (none were excessively loose or excessively tight)
Purge of fuel system and installed new fuel pump
Removed CAT and installed a gutted CAT.
Additional info:
Car has only 25,000 miles on it.
Previous owner had significantly overfilled the sump with oil. But now has the correct amount. Car was run briefly in the over-filled condition.
Car has never been driven since I purchased it.
Car has never been revved high since I got it running after its 15 year hibernation.
The car sat for several months after I got all the maintenance done and was then started up just yesterday and the noise was there almost immediately.
It is possible the noise has been there all along and was masked by the exhaust noises. As of yesterday when I first noticed the noise, there is no exhaust noise to mask engine noises because I have piped the exhaust out of my garage.
The noise sounded like it was coming from the AC pump so I removed the belt, but the noise is still there. I have included a video of the noise which was taken today, after the removal of the AC pump belt.
I checked for any interference between the fan and fan housing. I could not see any rub marks and an 0.008" feeler gage easily fit between all of the blades and the housing
I hope someone can give me some guidance.
https://youtu.be/nNM8E5zEwL4