Got a weird speedometer problem on my 84 Monte. the needle spins like a propeller as I accelerate instead of showing any actual speed. What would cause something like this? the trip and odometer still operate fine, just the needle is going nuts.

 

Speedometer Non Functioning or "Bounces".
The speedometer cable seems to fail frequently on these cars, I'm not sure why. A bouncing speedometer needle is a sign that the cable has a burr in it. Lubing the cable may alleviate it temporarily, but it'll come back sooner or later. Replacing the cable is the only permanent solution.
Check your cable connections on the rear of your speedometer, and also on your transmission...Good Luck

 

Its' not bouncing its spins around like a propeller, speeding up and slowing down depending on my speed. sounds more like a speedometer gauge to me, but I want to be sure before I shell out the cash on something I don't need.

 

Bad connection on cable, or worn speedo gears...
How many miles on your Monte ? Thanks : )

 

137K.... Whats the easiest way to check this? I've only had the car a week and a half, no idea if the cable or speedo has any work done to it.

 

https://montecarloforum.com/forum/sh...ad.php?t=12319

 

Its an 84, don't think that applies to my speedometer.

 

Any constellation....I have both problems....speed kinda bounces a little and I can hear some sqeaking sound (coming from speedo cable)
This is basic indications that it will probably break in due time.
Only thing is grease it.....if doesn't work, go ahead and look at speedo cable job. I think its pretty cut and dry as that im afraid.

On, but offtopic....was trying to figure out why my dash gauges weren't lit anymore....the speedo needle was sooo BRITTLE...it broke in about 3 pieces with the slightest bump.....sigh old cars can never expect the unexpected
Needless to say, the troubleshooting of getting my gauges lit again....to no avail without a needle now!!! lol
Take Your Time, Enjoy Your Ride :-D

 

On your gauge lights, had a similar problem. may sound dumb, sure you already did this, there are two fuses on the panel that affect these. My center ones don't work my other ones do, think these may operate like christmas tree lights, one bulb goes out the whole strip goes out. I have the same whining sound from my speedo, checked the trip and odometer, they are dead on, needle still spins, let's hope its a cable not gears.

 

Oh no, I had got my lights working...which is why I said, it made no progress getting them to work to see my speedo, when I end up breaking the needle anyway.....one of my bulbs are was iffy and I had to push and mess with it to come on....therefore I think they are not in series circuited
Honestly I truely didn't know out of all this time owning my Monte....you turn the **** clockwise/counterclockwise to dim your interior/dash lights........I probably could have turned my dash lights off on accident, because they worked one night and then didn't the next night......
But they work fine now....probably was just my user error (once again)