The downpipe installation procedure for a 1996 Saab 900 (also applies to the 1999-2002 9-3 models). The pipe is supplied by Jak Stoll. It is a 3" aluminized steel downpipe with a Magnaflow high flow catalitic converter.

Tools:

  • ramps or jack stands;
  • 13 mm socket or wrench: downpipe to turbo nuts, exhaust clamp bolts (a 1/2" worked better in my case due to a tighter fit);
  • 7/8" open end wrench: O2 sensors;
  • flat screwdriver: to release the tab on the O2 sensor connector;
  • a heavy tool or a length of pipe to bend exhaust hangers;
  • wire brush: to clean the joint between the flex pipe and the cat;
  • exhaust sealant: to seal the joint between the flex pipe and the cat;
  • torque wrench.
19.01.2005
Downpipe

The pipe and the box it arrived in. It was carefully cushioned by an immense amount of cardboard and other packing material ;).
19.01.2005
Downpipe

Surprisingly, the pipe weights less than you would expect from such a large piece of metal. It's actually lighter than the stock part, despite the bigger size.
19.01.2005
Front O2 sensor

You need to raise the front of the car to do the job (I used ramps). First, unscrew the front O2 sensor using an open ended 7/8" wrench. A bit of solvent would not hurt first. You might try to attempt the rear O2 sensor too, but there's very little clearance around it, so it's easier to take care of it later.
19.01.2005
Exhaust clamp

Undo the bolts on the clamp that connects the intermediate flex pipe to the catalitic converter. The bolts are 13 mm or 1/2". The joint would likely be sealed, so you will have use a hammer to break the bond after the clamp is off. Be careful not to put too much strain on the flex pipe.
19.01.2005
Front pipe

Unbolt the front section of the downpipe from the turbo. Two nuts are accessible from the top, and one from below. A 13 mm socket was a loose fit, so I used a 1/2" to escape rounding the nuts off. Two were OK, one was very tight, but a bit of solvent did the job.
19.01.2005
O2 sensor wire

Before lowering the pipe to the floor, unplug the rear O2 sensor (the middle connector on this picture). Remove the lower part of the connector from the housing and pull it down to let it hang free.
19.01.2005
Rear O2 sensor

Lower the downpipe with the cat to the floor (the length of the rear O2 sensor wire will allow that) and remove the sensor using an open ended socket or a 7/8" spanner. The pipe is free now.
19.01.2005
Old and new

The old downpipe compared to the new one. The flex joint on the old pipe rusted so much that it almost separated from the lower section (no wonder I had such a leak), and it only took me a slight pull to tear it off completely.
19.01.2005
Hangers

The hangers were made too wide and took some time to adjust. This was the biggest hassle: you need to put the pipe back on the car after each adjustment to check if everything fits properly.
19.01.2005
Fitting

Once you're happy with the position of the pipe, you can start putting everything back together. This is a good time to clean the O2 sensor heads with carb cleaner and check if the holes in the sensors are clogged with soot. Fit the rear O2 sensor before putting the hangers on. Put some antiseize on the threads to make the future removal easier. Tightening torque for the sensor: 41 ft-lbs.
19.01.2005
Front pipe

Once the hangers are on, fit the front end of the downpipe to the turbo.
19.01.2005
Front pipe

Make sure the the nuts are screwed on evenly, tighten at 18.5 ft-lbs.
19.01.2005
Exhaust joint

Clean the end of the flex pipe with a wire brush and fit it to the pipe from the catalitic converter.
19.01.2005
Sealant

Apply some exhaust sealant on the joint.
19.01.2005
Exhaust clamp

Put the clamp on and tighten the bolts to 15 ft-lbs.
19.01.2005
Front O2 sensor

Fit the front O2 sensor (also 41 ft-lbs, and don't forget the anti-seize), clean up and take the car for a test drive.

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