Front-end thunk

[rrevis]

I have a 1994 Caravan LE with a 3.0L automatic. I have had the trans rebuilt twice. Now I have have serious thunking noise and vibration when driving between 35-45MPH, only with accel or decel. If I press the gas pedal or let off the gas pedal the noise/vibration will stop. So it appears that it will not happen under load. Been reading all the threads here and elsewhere and trying to isolate the the problem. So far I have replace, in this order, The sway bar bushings, ball joints, struts and strut bearing/bushings. All to no avail. The problem still exists. The tie-rod ends seem to be tight, no wiggle. The wheel bearings seem to be tight, no wiggle when tire is lifted with 5' pry bar. Sunday I noticed that if I press the O/D button to stop the O/D from engaging the problem did not occur or at least very little/slight noise.
Could the problem be something in the trans/differentail ? Am I chasing a front end problem that is not in the front end? Sorry to ramble on but now I'm lost as to what to look for.
Russell

[whitebb]

Sounds like a broken motor mount. Dodge is famous for breaking the front one and having the symptoms you describe. Take a look at your van. On a positive note, the part is really cheap!

[rrevis]

I'm sorry, the first thing I replaced was the front/bottom motor mount. That is the square onr that sits upright like a diamond, right?

[whitebb]

I just re-read your thread, did you check the sway bar end links? (or are you calling these balljoints?)
Also check the cv shafts. Doesn't the right side have a 1/2 shaft with bearing then the cv shaft, or am I thinking the older cars only?

[rrevis]

I can't find the end links on this Caravan. Maybe they were on the newer models. Not sure how to check the the axels/cv joints. I have tried to move the shafts up/down and front/rear with no movement showing. Trying to turn the wheels right or left and trying to lift up with a 6' pry bar, when the van is jacked up, have no movement. But I can turn/rotate the wheels a little bit forward or reverse. Indicating some play in the trans, when in park.
Russell

[XDGT03]

The end links would be whatever is attached to the ends of the swaybar. It appears that the ones you have are different than later models. Ours are long bars with balljoints on the ends that attach to the strut and to the end of the swaybar. Yours might be very much shorter but should look similar.

You will always get a little rotation in the wheels when in park. That is normal.

My guess is the ball joints. Very dangerous to have one give way. This will cause a clunk and vibration. Possibly bad control arm bushings too.

[rrevis]

My 1994 caravan does not have sway bar links, as I have seen in the pictures. My sway bay lays across the frame, with a bushing on each side, and ends on the control arm, with a bushing at each end. These bushing were replaced as well as the control arm bushings and the ball joints and struts and strut bearings at the top of the strut.
What has not been changed are the axels and tie-rod ends. Also the wheel hubs and wheel bearings have not been changed.
Thanks,
Russell

[XDGT03]

The tierod ends definitely could be the problem but those are easy to check. Did you replace the inner swaybar bushings? Check the ball joints while you are there. Also, it's best to jack up both sides of the vehicle when checking components. the swaybar loads up the opposite side when one side is jacked up.

[rrevis]

Bump

[TomQuick]

This certainly sounds like it is more likely an issue in the drivetrain, perhaps an engine mount, or something in the exhaust system.

[rrevis]

A note to end this problem on. Saturday we took a day trip of serveral hundred miles. Sunday I checked the vans fluids, tires, etc. I noticed that the trans fluid seemed low. This is hard to read as the stick seems to get some fluid on it in the tube. So after several tries at checking I added about 3/4 of a quart trans fluid. Then I drove it to town to gas it up for my wife. I noticed that the thunking noise was gone. On the way home, still no thunking. My wife drives the van daily, so every evening I ask her if it still is making the noise. Her answer is always no. So last nite we drove to town for dinner out and I found that the thunking noise is still gone. Hard to believe that this was the cure to such an awful noise, until it comes back I can only assume that being low on fluid that the axels were bouncing in the trans housing or something like that.
Anyway, thanks for all of your responses and help with this. Maybe someone else can fixed their front end noise as I did.
Russell

[XDGT03]

That is scary. You had the trans rebuilt and they sent it back low on fluid? That is not good on the trans at all. Really really bad in fact. I hope it doesn't fail on you after a few thousand more miles.

[64_Barracuda]

Its your inner CV joints.