My car has almost 250K miles. It’s a great car and I’ve maintained it well, but it has a few quirks. One is that there is an intermittent noise coming from the dash behind the steering wheel- this started several years ago and mostly happens in cold weather, but not always. It’s sort of a scraping sound, and I’ve assumed it might mean the speedometer cable needs some grease. However, the speedometer is never erratic, the needle never jumps around when the noise is happening, and it works well. Any ideas what this could be? It doesn’t seem to have affected the running of the car at all.
if an air inlet duct flapper is a little loose (the foam on the door, where it mates to the duct deteriorates over time) it could cause this kind of noise. You need to get up under the dash and wiggle stuff up there if you can reach it while lying on you back on the floor in front of the seat, or just let it go and see what happens.
Well, you didn’t tell us the model year of your Civic, so we don’t know if it even has a speedometer cable. Cars have been using electronic devices for this function for quite a few years.
Regarding the noise:
Do you hear the noise only when turning the steering wheel, or do you hear it at all times?
Does ambient temperature have any effect on the noise?
Oh, sorry, it’s a 1988. So, yes, I am sure that things are starting to deteriorate because of age 
I didn’t know about the air inlet duct flapper! I will check that this weekend.
The noise is constant while the car is moving, but speeds up as the car accelerates (one of the reasons I thought it might be the speedometer cable. The thing that makes me question that conclusion is that the actual meter needle doesn’t vibrate during the times when I hear the noise. It moves as smoothly as it should. If the cable were binding, shouldn’t the needle hesitate or vibrate?) As I said, it does happen more often when the weather is cold, but it has happened also when the weather is hot.
Thank you for your help.