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Hi guys,
My brake booster (i.e. servo) on our 9-5 started to leak intermittently. I followed a tip described by Frans Swaalf of Amsterdam on another SAAB forum.
I did not find the WIS instructions very detailed, and I haven't seen a description of this procedure here on SAABNET that went into any detail, so here goes:
This is probably missing out a few details, but it should cover the key points and address what I found to be the harder things. My vehicle is a 1999 9-5 2.3L with the standard ATE brake booster/servo. I ordered the replacement ATE part from Eeuroparts for about $254.
My symptoms were an electric vacuum pump running too much - and upon checking multiple times I could occasionally hear a hissing leak from the booster itself, not the check valve or vacuum hoses. I did not have any CEL's.
General approach - to make more room, remove the battery cover and battery; undo the fuse clip / housing behind fuse box; remove 3 nuts (2 on top, 1 on side) from fuse box brackets, and lift box out of the way - on my car removing the 60 amp fuse block from the main fuse box was really tight and took much time/care. You need to remove the 'hood closed' switch from the main fuse box as well.
Now remove vacuum line from booster (plug pulls straight out).
The usual method of replacing the brake booster involves undoing the four backwards pointing Nylock® nuts connecting the brake booster drum to the bracket. WIS says to remove the master brake cylinder (MBC) by disconnecting the reservoir and then disconnecting the MBC from the ABS/TCS unit (the metallic object with the brake lines coming in and out). Disconnecting brake lines is a risk in itself without the proper open ring wrenches and extremely clean work area. Even after this is all removed, there's very little room to reach the 4 nuts. A socket won't reach them, and a normal box wrench hardly can be turned. Some have been successful with a gear wrench, but when I checked out the situation, it looked bad. My hands are too big
Easier approach - I read Frans Swaalf's write up, which he says came from a SAAB professional. Remove the brake booster with the bracket as a whole. This of course means undoing the bracket from the body. That bracket is a rectangular sheet metal box, with one bolt at the top and two at the bottom. The top bolt can be reached by removing the windscreen wipers, removing the plastic shield that guards the top end of the engine bay and removing a rubber plug in the base of the windscreen wiper bay, directly above the brake booster. It requires a 13mm socket with a bit of an extension. There are two bottom bolts (13mm socket) that are reached from under the car (use a lift or a high pair of stands, you will need some room - I had to add my last extension after pushing the rest with the socket up into place). With a long extension (60 cm, 2 foot) and a flashlight they came out quite easily.
Now undo the MBC from the booster (two 13mm nuts) and carefully pull and bend it (and the connecting brake lines) out and to the driver's side a bit. This leaves the fuse box flopped into the area where the battery usually resides and the MBC shifted forward and partly into the area where the fuse box usually is.
At this point, pull the brake booster forward to try to view the hollow connector that joins the brake pedal shaft to the booster. Press the brake pedal inside the car to push everything forward. There is a rectangular locking spring washer (circlip-like) that secures the brake pedal shaft to the receiving hollow rod from the brake booster. This washer is reachable (with little extra room) from the driver's side of the brake booster (right side as one works on the unit). It disengages by pushing upward — but TAKE CARE, it will jump out and could easily be lost! This part is not available from Eeuroparts. I discovered that by using my right hand and pushing this clip half way off I was able to pull the brake pedal backward from inside the car and separate the shafts without fully removing the clip.
The last thing holding the brake booster is an electric cable attachment clip at the underside of the bracket. This disconnects, starting at the passenger side (right side of car) of the bracket — I climbed onto the RF fender to reach down and undo this, and it slides to the driver's side to release.
The brake booster can then be pulled out and up, with some finessing of brake lines. Having removed the fuse box holder helps immensely here. As the ABS/TCS-module and MBC can stay in place, there's no need of bleeding brakes. It still maybe a good idea, if the fluid has been in the car a while, but the fluid in this car is only 15 months old, and I'll bleed again in the summer when it's not freezing in my garage.
Some additional snags - Windscreen wiper removal is usually a pain. I highly recommend the Lisle 'Batterey and Windshield Wiper' small puller, which is made for this job and can save you a windshield or wrecked wiper arm. Do not use a screwdriver, it will cost you the paint on the wiper, and/or the glass of the windscreen. There are probably other posts on this.
The plastic shield below it has some tricks also. It uses 5 clamps that hold the top end under the edge of the window. They will break (as I found out), but can be dislodged. Pull the screen a little bit up at the window side at the place where you can feel it clamp. You can see a little white edge of the clamp. Push this edge back with a screwdriver (down, parallel to the window - use cloth to protect the glass). After removing 2 small screws at each corner, the shield can be pulled up and out — start at the passenger side and you can twist it to avoid wrecking the hood release cable on driver side.
They always say that assembly is the reverse and a lot faster — But there are some items to watch: Compare the rod assembly on new and old boosters, adjusting the rod length accordingly. MEASURE (at least 3 X's). This will ensure your brake pedal returns all the way back to the sensor for the brakelights, and prevents you from having to undo the bottom dash to re-adjust.
Take care that all push rods line up. Replace the top bolt for the booster bracket first, but only fully tighten after starting the two bottom bolts. Before full re-assembly press the brake pedal gently to connect the pedal push rod to the booster shaft and check that they connect. Then finish re-assembly. Double check all connections — electrical and vacuum.
Would I do this job this way again - YES! The locking nuts holding my booster to the bracket turned out to be torqued on incredibly tight, and I went to my 1/2" drive socket set and big ratchet handle to loosen them. I also discovered that these 13mm nuts are very close to the bracket sides and my gear wrench wasn't small enough in outside diameter to fit onto them even out of the car.
I wasted at least half an hour deciding which way to attack this job. I wasted another half hour trying to take off the wiper arms with puller combinations that didn't quite fit before I went and bought the Lisle windshield wiper puller. It took about 4 hours, not counting my trip to the parts store to buy the puller.
Hope someone finds this useful.
Mark in Marin (MN)
posted by 74.46.228...
, Sun, 6 Mar 2011 12:08:54
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