Mysterious thump sound - suspension?

My 1998 Windstar makes a mysterious 'thump' sound that seems to be coming from the front right suspension area and happens when going over a medium to small bump or valley in the road. What are the possible cause of this and how can I research this on my own before bringing it to the mechanic?

I will mention that the first time this happened, the transmission soon went out on us and it turned out to require a MLP switch replacement. Is it also possible that this is somehow connected with the transmission? After that incident, the van was taken to a transmission shop and they ran tests that did not show anything in particular that would require replacing or fixing the transmission, the new MLP switch seems to have taken care of that problem. Nevertheless, I can't help connecting the problems since the thump sound was first heard right before the old MLP switch went bad.

Is it also possible that something is just loose - maybe inside the door or wheel well on the front right side? Sometimes it sounds as thought that could be the cause of the thump sound.

Any help in tracking this down would be much appreciated.

Ive worked on vans that had a thumping sound when the body moves. Both times it had to do with the stabilizer bar. The first time it was the link assembly that hooks the stablizer bar to the shock assembly. It was broke and hitting the control arm. The second time it was the stablizer bar bushings. THey were stuck to the bar and wasnt allowing it to move. If your van has done this since you had it last worked on, it may be possible that the mechanic didn't get everything tightened back down. You can do the bounce test to try to find the problem. Have a person rock the body of the van somehow to try to cause the noise and have someone else listen and try to find the problem. Thats how i found my two problems.

The two problems that you should research here from the windstar front page search is broken spring and the lower strut rod. That may be listed as thump, thud sound front, etc. The tension strut passes through the front frame cross member and a washer/cup arrangement that holds the rubber bushings comes loose from the frame and that is what you are hearing. There are a couple of repairs from welding to a repair kit by Moog I think. Wiswind, the moderator actually has a collection of well documented pictures with this exact condition and repair. One other possiblity is something rubbing against something in the wheel well area often against the spring. I don't think I've heard much on the strut tower making that kind of noise, but it's possible if it's loose.

i'd be looking at the stabilizer bar bushings as well. I've replaced mine each 2 times and I've only got 130,000 km on my van. They go prematurely in my opinion.

Piper

Just another thing to consider, depending on how loud the thump is, rocks/gravel can collect in the top of the cup so that when the spring compresses, it hits the rocks and makes an awful sound. I get this every winter. The dealer told me about it b/c it is very common complaint. He said to just wash out the spring area and the debris will come out. It worked for me, but it is an ongoing thing (happens a few times a year).