Exhaust Downpipe

Has anyone tried to remove the exhaust downpipe from a 1990 Transport SE 3.1 V6 engine. The pipe appears to be held in place on the manifold by springs?

I'm afraid to try and remove anything in case the bolts/nut snap/break.

The exhaust is throaty/roars under hard accelleration, but there are no leaks on the system at ground level. The noise is worse when reversing up a hill for example.
:)

Are you referring to the flex section as the "spring"? If the 90 3.1 is anything like my 98 3.4, there is a flex section on the rear of the engine on the downpipe after the O2 sensor mount. This provides some flexability from engine movement/rolling forward. If it was rigid, something would break over time due to vibration or over flexing.

Exhaust bolts are always a tricky thing. After any amount of time, they usualyl become very rusty. Luckily, they should be hardened bolts and a impact wrench typically can loosen them. WIth a regular socket wrench or breaker bar, you run a higher risk of twisting them off. You can still remove them, but it becomes more difficult.

I'd jack the vehicle up and let it cool down completely. Then have someone start it while you feel around the flex section. I've had a few exhaust pipes rust out around the flex section and it was difficult to see but easy to hear and feel the leak. Another area would be where the downpipe attaches to the manifold, where the crossover pipe attaches, or at the manifold/head itself.

The 3.1 and 3.8 of that vintage are similarly arranged. THe springs maintain pressure on the DONUT (www.avigex.ca/xport/donut.jpg ) shaped seal that allows for some swivel, and this donut is a limited time component that then leaks with a disgraceful sound...that varies with torquing conditions (reverse, acceleration...)
I am about to install the fourth..the 2nd was on warranty, and I changed the third like 5 years ago. I do not remember for sure if the manifold is threaded or if there are separate nuts..I think separate nuts, then no danger.....I should have written this down...I"ll do it this time.....but I remember I had no real difficulty removing the bolts that stress the springs..
The bolts and springs come as a separate kit ...I'll see if I keep the old or start fresh with new items.
..I should have centered the DONUT (www.avigex.ca/xport/donut.jpg ) so all equivalent part numbers are readable...in addidion to those visible there are GOERLICH 9221, IMCO 124675 MAREMONT G229