trans rattle only in D while braking

Today my wife called and said that the van (2000 3.8) was making a rattle/metal sound. I met up with her and sure enough, there was a rattle sound (kind of like when the catalytic cover rattles but quieter). The funny thing was, it only did it when the trans was in drive, with your foot on the brake. Put the van in R, N, P it wouldn't make the noise; put it in 2 or 1 with your foot on the brake again it would rattle. Immediately shift out of D and the rattle would stop.

So, I really scratched my head and wondered. I topped up the trans fluid, which seemed to make a small improvement. Fortunately I have a lift so I decided to put the van up and look underneath. The other thing that was interesting was that when the van RPM sat around 750-800 the rattle wasn't apparent; at ~500 it was.

Anyway, long story short, I found that an exhaust clamp that joins the flex pipe to the following section had become loose, and thus the rattle. It seems that the lower RPM led to the rattle and when the van was in drive with your foot on the brake, the RPMs dropped, causing the exhaust to vibrate...

I post this because it reminds me again that we need to really be open to "what ifs" when we're looking to find the cause of all the various issues we have to deal with on these vans.

For me, a 2 inch $2 clamp solved the problem. Good thing too... I can't afford the time or money to replace the trans right now :rofl:

Same thing happened to me. That exact same clamp practically disintegrated off of ours. The flex pipe was pretty well rusted to the muffler and it was driven that way (sans clamp) for a few weeks, but eventually I put on a new clamp anyway just because, like you said, it's $2.

Nice find.