Volvo 240 Vibrational Frequency While Accelerating Problem

jkintner · Post by **jkintner** » 14 Jan 2013, 10:13

Hello all,

long time reader, first time poster. This one has stumped me for a while now. I have a 1987 Volvo 240dl automatic, runs great!, but there is a noise whenever I accelerate. It seems to be a vibrational frequency noise coming from the front end of the car and only seems to arise when I'm accelerating. It happens only when the gas petal is only about half engaged and I'm just about to shift up into another gear (its an auto). Most of the time it goes away when I give it more gas.
I read up on it and within the depths of cyberspace and got many possible explanations, from propeller shaft bearings to motor mounts.
If anyone out there can pinpoint this one I would be very grateful.
thanks a bunch

Post by **JDS60R** » 14 Jan 2013, 10:30

This is one of those things you have to inspect to find.

Many times the Prop shaft joints or center bearing are to blame. The front end suspension parts can also have play in them. Put the car up on a lift and check for shaft wobble. Then inspect the front end components. Also check for broken motor mounts and any failed rubber bushings in both front and rear. The torque your motor makes will try to escape in any loose area so mounts, bushings, suspension joints and bushings as well as prop shaft joints and bearings all need to be inspected.

jkintner · Post by **jkintner** » 14 Jan 2013, 22:01

ill take a look at whats mentioned above.
thanks a lot

lindy8_man · Post by **lindy8_man** » 15 Jan 2013, 02:12

I'm also wondering about a harmonic balancer issue. Any of our moderators know how those fare over time? I had to replace it on my first car (66 mustang 289ci).

More information can help to localize:
Do you have a Tachometer? Are you getting the vibration at the same RPM? If you put it in park and rev to that RPM do you have the same vibration? CAn you feel the vibration in the steering wheel or is it just something you hear? What does it sound like? Does the vibration match the "frequency" of your RPMs? How old are your tires / when was the last time you had them balanced?

Post by **JDS60R** » 15 Jan 2013, 10:09

Good point . Crankshaft harmonic balancers do fail as the rubber hardens and fails. Its symptoms would be rpm dependent as mentioned earlier.

jkintner · Post by **jkintner** » 15 Jan 2013, 12:45

Good idea on the Harmonic Balancer, I'll add that to the list for inspection
The frequency does tend to be rpm dependent. The noise is a subtle but prominent vvwrrrrrr noise (fades away when giving it more gas).
Although there is no tachometer, the frequency at which the noise arises is when it's just about to shift (mostly 1:2 and 2:3 gears) or the gas petal is depressed to a certain point (about 1/3 way to the floor). Pretty much that leads to believe it is rpm dependent
Now that I took a look at my records, I do remember getting an alignment and tires less then 5000 miles ago, and I can't feel any vibrational coordination in the steering wheel.