09.10.2005: Garrett T25 Turbo Rebuild

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09.10.2005: Garrett T25 Turbo Rebuild

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This Garrett T25 turbo is found on 1991-1998 Saab 9000, 1994-1998 Saab 900 and 1999 Saab 9-3. There are certain differences between the models, but the cores are almost identical, so you might find this useful even if your unit is somehow different from those pictured. The goal of this job was to rebuild a turbocharger using new seals and bearings from a service kit.

Tools and supplies:

14 mm six-point socket (turbine end nut);
13 mm spanner wrench (exhaust housing bolts);
10 mm wrench (wastegate actuator);
8 mm twelve-point socket, did without it (compressor wheel nut);
Torx T15 screwdriver (thrust bearing);
small torque wrench with an inch-lbs scale;
large and small snap ring pliers;
gear puller;
engine oil;
degreaser and cleaning supplies.

	09.10.2005 Two turbos These are the two turbos I'm going to use. One has damaged wheels and incredibly worn seals, while another has a cracked exhaust housing but good internals. I'm hoping to combine them into one working unit.		09.10.2005 Donor No 1 A close-up of one of the turbos. This one came from a 1999 9-3. The wastegate actuator has been removed earlier.
	09.10.2005 Bolts Undo the bolts on the exhaust housing using a 13 mm spanner. The bolts are conveniently located so they can be used to press the housing off the turbo.		09.10.2005 Exhaust housing When using the bolts to force the housing off, do it very carefully, half a turn at a time. Make sure it is coming off evenly and not jamming the turbine wheel.
	09.10.2005 Snap ring The compressor housing is secured with a big snap ring, you need large pliers for that.		09.10.2005 Compressor housing The snap ring takes a few moments to wrestle, and then you can remove the compressor housing... carefully.
	09.10.2005 Shaft play This shot illustrates the enormous amount of shaft play on one of the turbos. The thrust bearing was completely destroyed, so the turbine ate into the backing plate and grind itself down over 2 mm.		09.10.2005 Nut Grab the shaft nut with vise-grips and use a six-point 14 mm wrench on the turbine end to undo the nut. Remember, the nut has a LEFT HAND thread.
	09.10.2005 Gear puller The compressor wheel might just come off, but most likely you'll have to use a gear puller to press it off.		09.10.2005 Wheels removed Before pulling the wheels off, even before touching the nut on the shaft, mark the position of the wheels relative to each other. You'll have to assemble them in the exact same position later to preserve the balance.
	09.10.2005 Sealplate The sealplate is held by another snap ring, and there's a rubber ring underneath.		09.10.2005 Thrust bearing The thrust bearing is held by three Torx T15 screws. The thrust collar is the part mainly responsible for shaft play.
	09.10.2005 Snap ring The journal bearings are held in place by small snap rings. You can remove them with tiny needle-nose pliers or just an awl.		09.10.2005 Journal bearings The intake side journal bearing has only one snap ring inside the turbo (the outer side is propped by the thrust bearing), while the exhaust side bearing has two snap rings.
	09.10.2005 Cleaning Time to clean all the grime and oil from the turbo. Check for sludge in the oil passages. Keep all parts free from contaminants from now on.		09.10.2005 Wheels Clean the wheels. Make sure you did not wipe your position marks if you used a marker or paint. Remove the old seal ring from the turbine.
	09.10.2005 The kit A typical T25 service kit from eBay would contain a full set of new bearings, seals, snap rings and fasteners.		09.10.2005 Journal bearings Prepare journal bearings and snap rings. Some kits come with bearings in two sizes to suit different trims of the turbo, so pick the right size.
	09.10.2005 Snap rings Install the inner snap rings on both sides of the central oil passage. Make sure they fully fit into their grooves.		09.10.2005 Turbine side Dip one of the journal bearings in engine oil and insert it on the exhaust side of the turbo. Fit the outer snap ring.
	09.10.2005 Compressor side Turn the turbo around, dip the second journal bearing in oil and slide it in place.		09.10.2005 Thrust bearing Fit the seal ring on the thrust collar, dip the parts in oil and screw on the thrust bearing.
	09.10.2005 Sealplate Install a fresh rubber ring under the sealplate, press the sealplate in and secure it with a snap ring.		09.10.2005 Turbine Prepare the seals that go on the turbine end of the shaft.
	09.10.2005 Turbine seals The middle retaining ring was completely missing on both turbos. Its groove was filled flush with cooked oil, so I had to dig through it. The installation of the shaft is a bit awkward since you have the back cover plate blocking the view, but sooner or later it snaps in. Just don't force it too much.		09.10.2005 Compressor wheel Slide the compressor wheel on and line up the marks carefully to restore the balance. Put on the nut. The torque varies from 20 to 40 in-lbs in various sources, plus extra 90-120°. Ideally, you need a small 12-pt socket for the nut, I just clamped it between two wooden blocks and used a torque wrench on the turbine end.
	09.10.2005 Compressor housing Fit new rubber ring, put the housing on, and secure that huge snap ring. Check the orientation: if the outlet of the housing points down, the part number plate on the cartridge body (or the stud that's left of it) should point up.		09.10.2005 Exhaust housing Fit the exhaust housing, new brackets and tighten the bolts. As usual, make sure the turbine spins free.
	09.10.2005 Wastegate actuator The wastegate actuator has been rebuilt and prepared earler, with an upgraded spring from Nordic.		09.10.2005 Finished Bolt the actuator to the housing and screw on the arm so it slides onto the wastegate arm in the closed position. Shorten the rod an extra 2-3 turns to obtain a pre-load of 2-3 mm, and tighten the lock nut.

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