"howling" noise when not accelerating
Thread Starter
Cruising
Joined: Oct 2019
Posts: 10
Likes: 2
From: Freehold, NJ
"howling" noise when not accelerating
Hi,
When i hit about 45 MPH and take my foot off the accelerator, i hear this low "howling" noise (no idea where it's coming from though likely underneath the car). If I just tap the gas, no noise. take the foot off the gas, the noise comes back. Only happens when I get up to 45MPH and disappears after 60MPH. I ruled out any type of "wind" or air noise as it only happens when i accelerate (even the slightest touch of gas peddle). One mechanic thought it may be the differential, but given it only happens in this small range and otherwise the car is driving OK, that it's likely not a big deal. Thoughts?
Thanks Johnny76
When i hit about 45 MPH and take my foot off the accelerator, i hear this low "howling" noise (no idea where it's coming from though likely underneath the car). If I just tap the gas, no noise. take the foot off the gas, the noise comes back. Only happens when I get up to 45MPH and disappears after 60MPH. I ruled out any type of "wind" or air noise as it only happens when i accelerate (even the slightest touch of gas peddle). One mechanic thought it may be the differential, but given it only happens in this small range and otherwise the car is driving OK, that it's likely not a big deal. Thoughts?
Thanks Johnny76
Tech Contributor
Joined: Aug 1999
Posts: 15,188
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From: Connecticut, USA
Could be pinion bearings but as mentioned new gears, even US gear will make a noise in the 45-60 mph range once letting off acceleration. US Gear now prints this out in the spec sheet with new gears.
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I agree on checking the lube. Check the tranny level as well. If you cant identify where it is and you want to, I would fill the diff and then drive it. Then fill the trany and again, drive it. Then check all the u joints for grinding or stiffness but you have to get the rear half shafts to a level relative to the diff that wont let them bind. And grease them if they have zerk fittings then drive it again. If that doesnt do it you can check bearing play but you have to jack up the rear again and have a helper. You need to determine bearing play and not confuse it with the half shaft movement. I agree with the others that if its a small mph range and not an RPM range then i wouldnt worry about it until it gets to a point you can identify it to rectify it. To check rpm, if you can hear it, get the car up to that speed in a different gear and/ or check the rpm in the given gear when the noise appears and get the car up to that rpm in a differnt gear and see if it appears. If its just speed related in that gear at that speed it still could be a tranny gear but the chances get lower.
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
In my 77 I had a 3.08 to 1 which had a distinct whine at 60 km/h , not 59 not 61 ! ! ! ! apart from that it went ok. I sold the diff to a guy during my car rebuild as I got a 3.36 to 1 to use . I told him there's a problem with it before I sold it but he wanted to change gear ratio anyway so it was ok. Anyway he opened it up and the pinion gear was in 2 pieces !!!
