Noise at 20 mph

1988 740 Volvo Estate.

At around 20 mph I get a strange rumble noise.
I have tried the car downhill with the engine off, ( no other traffic
around ) and the noise is there so the noise must be in the transmission or
wheels.
The noise does not appear to be coming from either of the rear wheels.

I note that the Speedo works off the back axle, could it be this making a
noise if not ay suggestions on what the noise may be.

 

It could not be the back axle noise being transmitted to the speedo as the
connection is purely electrical. Possible culprits are - exhaust system touching
chassis or underside (could be due to engine mounting or gearbox mounting
failing), centre bearing on propshaft failing, wheel bearings, gearbox tailshaft
bearing, and there are a few more!! Start by eliminating the ones I have listed.
If you do not find it then come back and we will look up the others.

Cheers, Peter.

: 1988 740 Volvo Estate.
:
: At around 20 mph I get a strange rumble noise.
: I have tried the car downhill with the engine off, ( no other traffic
: around ) and the noise is there so the noise must be in the transmission or
: wheels.
: The noise does not appear to be coming from either of the rear wheels.
:
: I note that the Speedo works off the back axle, could it be this making a
: noise if not ay suggestions on what the noise may be.
:
:

 

[ ... ]

In addition to the other suggestions, check your universal joints.


Gary