01 t/c front clunking sound

[Cntrysthbst]

I only hear it going over a bump that both tires ride over, at a slow speed. When the tires drop down from a paved road to dirt road for example this is when I hear it. Everything is tight suspension wise. Sway bar bushings and end links are new. Rims are tight. Lower ball joints are greased. Struts are good, brakes are new. It's like something is loose, I had the engine/transmission mounts checked are was told they are good. Any ideas? Thanks

[KManiac]

I am not that big of a gambling man, but I would bet money your van is "All Wheel Drive" (AWD). Correct me if I'm wrong, but if I'm right, I know exactly what is happening!

The answer is.......

[Cntrysthbst]

Don't have the all wheel drive, it still does it. It's in the front end, I only hear it when going over a slight drop off to dirt at 5 mph or so. I have to go back to the dealer Friday to get the PCM re-replaced again and they said they'd check it. I do have a metal clapping sound in the right rear, like a loose brake shield but its not loose. Don't know what that is either, I took the tire off and checked but found nothing, everything is tight.

[hkmorgan87]

A front clunking noise is very common on both caravans and t/c's. Depending on mileage you could have a few concerns. Links and bushings are the most common problem. Not a serious problem, but annoying to listen to. Depending on use and mileage, you could also have loose tie rods, or loose balljoints, which are both serious problems. Just keep in mind, appearances can be deceiving, just bc a part looks new doesn't mean its working right.

[RIP]

In the front - upper strut mounts? In the rear - tire jack, spare tire, exhaust, loose metal fuel/brake/a/c/heater line? I had a clunk in the rear once. Turned out to be the wheel well liner coming loose on the drivers side.

[Cntrysthbst]

Hmmm, probably all of the above! I am going to replace the control arms because of ply I noticed when checking. Now I was thinking of replacing the strut mounts to but ify about the struts. They seem fine from what I've been told. I do hear a swishes of air every time I go over bumps at 15 mph on dirt roads, is this a normal sound? Both front sides do it. Has about 90 on it. Thanks

[MdPhoenix]

Originally Posted by KManiac

I am not that big of a gambling man, but I would bet money your van is "All Wheel Drive" (AWD). Correct me if I'm wrong, but if I'm right, I know exactly what is happening!

The answer is.......

I have an AWD '98 GC. Could you tell me what the noise is, please?

[stewart443]

I have the exact same symptoms. What did you end up doing to fix it?

[KManiac]

This message is for all AWD owners who experience a cluncking noice upon application of the throttle. This applies only when the engine is under load and with the tires on an unstable surface.

The AWD system is NOT a full-time system that splits driving force equally between all four wheels continuously. It is a standby system that works in similar fashion to the old "limited slip" differentials used in RWD cars. The front wheels are the primary driving wheels in these vehicles with the left front receiving more driving force than the right front. When either one or both of the front wheels begin to loose traction, the PTU engages and transmits driving force to the rear wheels.


Now, I and other AWD owners have reported a condition with these beasts that I call the "AWD Clunk". This is a very rare condition that baffles most owners and mechanics, including the dealer mechanics. This has happened many times to my wife (the primary driver of our van). It usually occurs when she puts the van in reverse and starts to back up out of the driveway or a parking space. As soon as the van starts to move, you will hear and feel a clunk and have the sensation that you just ran over something. Then, when you try to reproduce it, either yourself or at the repair shop, it won't happen.

My theory on this condition is that the van suffers a momentary loss of traction of both front wheels simultaneously either from unstable ground, dirt, mud, ice, wet leaves or parking space paint stripes. When both front wheels spin simultaneously, full drive power is suddenly diverted to the rear wheels, causing sudden engagement of the clutches in the PTU. This would account for the sensation similar to dumping the clutch in a stick shift car. AWD owners are more familiar with this condition in snow country where icy roads can cause this condition on a regular basis. But here in sunny California, well below the snow line, a loss of traction is a rare occurance. Our van has never seen snow in seven years. This condition is not a symptom of pending failure, it is an inherent reaction to specific conditions that proves the system is working as designed.

Think about the times your AWD van has suffered a mysterious clunck and most likely it will be under similar conditions as I described above. Let me know if you have any questions or comments.

[stewart443]

I'm not AWD. I haven't visited this forum in a while but thought of htis old post and wnated to see what was the fix. I now notice a more recent post that sounds similar ragarding bad strut mounts.

http://www.automotiveforums.com/vbul...d.php?t=908660

this one as well

http://www.automotiveforums.com/vbul...d.php?t=909313