Good Ol' Red-x7 FB

Hello, just joined the club! Hopefully this post reaches the right spot.

So it all started 2 weeks after purchasing my 1984 12A GS 5 speed. It sounds amazing and drives smoothly but I've noticed a couple odd noises emitting from the car.
There are only two that I am actually concerned about at the moment...

1. When I take my foot off the accelerator pedal I can hear a "Pft.. Pft.. Pft.." noise while coasting. This sound comes from the bottom of the car and I have been thinking for awhile that it
could be caused by a hole in the exhaust system/housing? This is not a big deal, but if I can fix it I might as well.

2. The noise that bothers me most is what at first sounded like a rattling treadmill of beads being wound up faster and faster as I gained speed. The sound would be drowned out by the time I hit mid 3rd gear,
but at the time I didn't worry about it too much- thinking it was the speedometer cable. A few days ago I removed the instrument cluster and replaced all halogen lights with new LED bulbs. I disconnected the spedo cable from under the car to do this, and then screwed it back in once I was finished. I made sure to give the instrument cluster a little slack and there are no sharp bends in it.

I don't know for certain if it was this cord causing that noise but after finishing the job I could drive around town with no odd dash noises... for three days. It started again, and grew in sound gradually about 10 minutes after I start driving but it wasn't awful.
Now the dash screams at me! It's no longer a treadmill noise but more of a "EEEEE". Before I stop at red lights I need to crank up the windows so that nobody stares at me . I get dizzy from driving with it on too long. The sound only comes from inside the dash, but it is hard to retrace the source. It just sounds like it is coming from in between the radio and cluster. Maybe the spedo cable was never the problem?

No sound can be heard from the engine bay, and it does not sound like a buzzer. I have no warning lights on.

Has anyone experienced this?

AnUnusedUsername

This may be a dumb suggestion, but are you sure it's not the tape deck stuck on fast forward or rewind, or the electric fans? If I put my fans on high they do sometimes rattle or whine a bit, I could see a failing one that was stuck on full blast making some noise.

Good Ol' Red-x7 FB

Unfortunately not, I've experienced "the noise" even while listening to a cassette playing. I've also double-checked the fans to see if they are running but looks like they are fine. Definitely not a bad suggestion- but the noise seems far to consistent to be caused by a misbehaving fan...

DivinDriver

iTrader: (15)

If the sound only occurs when the car is moving, and changes pitch with road speed (as opposed to RPMs), it could be something in the speedo cable or mechanism. But if it happens when you are at a complete stop, it's not anything to do with the speedo system.

Easy way to test this would be to disconnect the speedo cable at the trans end, carefully strap it up out of the way, go for a brief drive and see if symptom changes. The cable housing connector screws on and off with hand pressure (or possibly careful application of pliers). Driver's side lower on the trans, black cable with a ~1" silver knurled ring that holds it on.

If this does change symptoms, then it it either the cable itself either being improperly inserted in the back of the cluster, needing lubrication, or having broken, or something in the speedo mechanism like a bushing binding or wearing. The system is 100% mechanical and quite simple in design.

If not, it's something else entirely.

Good Ol' Red-x7 FB

Thank you for the help, I'll try that out in the morning and see what happens.

LongDuck

I'll tell you right now, it's your speedometer cable where it enters the back of the speedo. My car makes the same noise when it's cold out, as the grease inside the speedo gets thicker and poses more resistance for the square-end of the cable where it enters the clockwork mechanism. The speedo having 233k miles on it, has seen a LOT of revolutions, and the receptacle where the square-end fits can slip out of place and get noisy. A quick fix might be to reach up under the bottom of the dash over near the gas pedal (*there's nothing much under there anyway), and try to feel for the cable where it comes though the firewall and goes to the speedo. If you're lucky, you can just push it back in a little further and hope the noise goes away. If not, you'll have to pull the gauge cluster out, and will still need to reach up there to disconnect the cable from the back of the dash gauges prior to removal.

Good luck, and report back what you find; speedo cables show as NLA via Mazdatrix or I would have replaced mine log ago...

Good Ol' Red-x7 FB

Before work today I gave the spedo a little more slack and tried greasing up the connection underneath- but it got loud again during the drive. You might be right with the connection to the cluster. I'll order some brighter bulbs for the dash (the recently installed ones are proving to be pretty cheap in brightness) and complete the operation this week sometime to kill two birds with one stone. Stay tuned for an update..

Good Ol' Red-x7 FB

Took her off and drove for a bit in silence, sounds like that cluster connection is the problem. Thank you.