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"Mourning" sound on ´68 DeVille...

1122 Views 10 Replies 7 Participants Last post by  drmenard
Hello everyone,

I drive a ´68 DeVille and I have a problem that I thought someone
may have some advice on...
When driving the car at speeds above 50 mph and taking my foot OFF the gas pedal a sort of "mourning" sound appears.
As soon as I step on the gas again the sound disappears.
Also I can feel slight vibrations at speeds between like 30-50 mph.

I´d be very happy for any advice I can get from you guys.

Kind regards from Stockholm, Sweden.

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I'm usually in "mourning" after filling up the gas tank. :ill:

Is the sound you hear coming from under the hood, or rear of the car? Probably would be a good idea to check the fluids in your transmission and rear axle just to play it safe.
Torque converter maybe? I'm trying to envision a "mourning" sound, something like a prolonged deep groan? I agree with Highway Star, we need more info, please.
If it's a kind of whir sound, that changes pitch when the car changes gears, the tranny bands might need adjustment or rebuilt, if the pitch stays the same, by all means, drain and refill the gear oil in the pumkin!! (differential)

Watch the magnet on the inside of the filler plug though, that'll gauge how worn or not worn the Ring and pinion are...........
Hi guys,

Well, first of all - pardon my "Swenglish" regarding the word "mourning" !
What I meant to write was "moaning" !!
It´s hard to tell if that´s the exact word for´s like a deep buzzing sound
from underneath the car.
I had the u-joints replaced like two weeks ago and the mechanic who helped me noticed 2 dents on the propeller shaft. I guess these can be the reason I´m noticing the vibrations at like 30-50 mph.
Do you think that these dents also can cause the sound that occurs when taking my foot off the gas pedal at higher speeds ?

Thanx for your help !

Stefan from Stockholm, Sweden
Hi Stefan,

Did you purchase your Cadillac in Seattle Washington? I sold a 68 coup to a couple of Swedes a few years ago. I would love to see any pictures of any restoration work that you have done... if you are the same guy.

If not... well... good luck with the moaning and higher speeds. :bigroll:

If I was to take a guess, I would say it sounds like your pump in the transmission is making the noise.. if so it will need to be rebuilt...
Hello again,

Bubbalac - I´m afraid this is not your old Caddy. This beauty came from California like 3 months ago.

About my problem...The transmission works very well and shifts smoothly.
My guess is this noise is coming from the either the propeller shaft or the differantial. I´ve been trying with all sorts of tools to loosen the filler plug back there but it is stuck like !#¤!*¤#!
Like I mentioned the sound only appears at speeds above 50 mph and with no throttle...

I´m now thinking of trying to find a new propeller shaft which is without any dents and see what happens.

Still very grateful for new advice on this matter.

Take care / Stefan from Stockholm, Sweden.
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Well, a dented "propeller" shaft wouldn't really throw off the balance, unless it got slightly bent in the process, like if it bottomed out, and hit the shaft, which is rare..........Check the undercarriage for any visible dents/scratches, and it might reveal a history as to why your Caddy is acting the way it is....

And a crescent wrench is the best tool for that filler plug...........
Dents in the drive shaft? It WILL be out of balance and probably cannot be balanced.
maybe the best way to get your plug out is to use heat ..heat all around the plug, trying not to put heat right on the plug after what you are saying , if it is the driveshaft and is out off balance because of a dent, the only way to fix that is by a drive shaft shop... but if it is a bad u joint, that can be fixed by you but is a little tricky.. they a a type of CV joint with 2 u joints together..the trick is when you are putting it together, put both the joints together at the same time..if you put one joint in all the way with the snap rings , you can not get the second joint in.. If you have a bad pinion bearing, just hope the race did not spin and damage the case...
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