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Garrett T3 Rebuilding
By Brian Leavitt
Rebuilding your own turbocharger is really not nearly as difficult as you might think. It can in fact be accomplished in an hour or two once it has been removed from your vehicle.
What you will need:
1. Turbo rebuild kit – I got mine from G-Pop Shop (www.gpopshop.com). They are an authorized Garrett distributor. Others have gotten them elsewhere such as Evergreen Turbo and some other places, but I like personally like the G-Pop shop. They are extremely helpful and courteous. If your budget allows, you should opt for the 360-degree thrust bearing and step-gap piston ring (more on that later).
2. Assembly Lube – Very important when re-assembling your turbocharger.
3. Snap Ring Pliers – I like the Craftsman version of these because you can switch them from internal to external mode with the flip of a switch on the fly.
4. Caliper – I prefer a digital caliper myself, but a good old dial caliper will work just fine.
5. 3/8” - 12-point socket – For compressor wheel nut.
6. 13mm Wrench – For turbine & compressor housing bolts.
7. 10mm Socket – For backing plate bolts.
8. Pick – a 90-degree pick will suit this purpose the best, but any will do.
9. Five-gallon bucket.
10. Automotive Touch-Up Paint – For marking the compressor wheel, center section, turbine wheel, etc.
11. Rubber mallet.
12. PB Blaster or similar product.
13. Bench vise (preferred) or vise grips if you do not have access to a vise.
14. 1-lb. Dead-blow hammer (possibly).
15. Some type of cleaning solvent to clean the entire turbo before re-assembly.
16. Paper towels, shop rags, etc.
17. CLEAN-CLEAN-CLEAN Work Area!
Note 1: Before you really dive into this, please realize that it may actually take a few days from start to finish. Mainly because you will probably have to soak your turbo in PB Blaster in order for the turbine housing to come off. All that heating, cooling, and rusting can get it lodged on there pretty darn tight. If after a few days of soaking the housing will still not come off then break out the Dead Blow Hammer. PLEASE NOTE: DO NOT repeatedly hit the same part of the housing with the hammer! Doing so can SERIOUSLY DAMAGE THE TURBINE! Work your way around the entire housing with the hammer and don't whack the crud out of it. Just moderate tapping should do the trick. It may take a while, but it will come off.
Note 2: From personal experience I would recommend disassembling the turbo before ordering your rebuild kit. There are 2 reasons for this. First, if your turbo has been rebuilt in the past, the bearing journals may have had to be machined in which case the standard bearings that come with the rebuild kit will not work for you. Oversize bearings are available from your rebuild kit supplier in several sizes to suit your needs if this is the case. Second, you may find that your turbine shaft or bearing journals are damaged in which case you will need to send it out to be machined anyways and at that point you might as well just have them do the entire rebuild.
Note 3: If you turbo is needing a rebuild because it has seized I would suggest you just send it out to get it done by professionals. Chances are there is going to be some machine work involved as the bearing bore or turbine shaft is most likely damaged.
The Procedure (Assuming you have not ordered your rebuild kit yet)
Exploded View of Garrett T3
Disassembly of Major Components
1: Remove your T3 from the car and place in your 5 Gallon Bucket. Soak with the PB Blaster, paying special attention to the area where the turbine housing mates with the center section. Re-Soak every few hours or when time allows for a couple of days.
2: Dry off the outside of the turbo where you plan on making your marks with the paint. Mark the Compressor Housing, Turbine Housing, Backing Plate, & Center Section with the Touch-Up Paint so that you can re-assemble it as it was when you pulled it off the car.
3: Remove the 13mm Turbine Housing Bolts & Remove the Turbine Housing. You will notice that they will not all come out without hitting something. You are going to have to remove the ones that come all the way out. Then the ones that will not come all the way out will have to be removed by alternating between loosening the bolts and pulling the Turbine Housing off in steps. If your Turbine Housing will still not budge after soaking with PB Blaster for a couple of days, please refer to Note 1 above.
You will notice that the Turbine Nut is an odd shape. The Turbo is balanced at the factory by removing material from various sides of the nut, giving it its shape. There is nothing wrong with the turbo if you see this (and you most likely will).
4: Remove the Compressor Housing Bolts & Remove the Compressor Housing. This one is simple compared to the Turbine Housing. Make a note of where the Wastegate is bolted to the Compressor Housing. You can mark it if you like. I just made a mental note.
STOP:
At this point you should inspect both your compressor wheel and turbine for any damage to the fins. If you find that either one is damaged you will probably want to stop here and either send it to a reputable shop to be rebuilt or start looking for a new turbocharger. Also check the inside and outside of your turbine and compressor housings for cracks.
5: Mark the Turbine Wheel in relation to the Center Section & the Compressor Wheel in relation to the Backing Plate. This is a VITAL STEP to make sure the Turbocharger remains balanced when you re-assemble it.
6: Secure the Turbine Nut firmly in the Vice. If you don't have a vice available, Vice Grips will work, but you'll be making the process more difficult on yourself, especially during reassembly.
7: With your 3/8” - 12-point socket remove the Compressor Wheel Nut and remove the Compressor Wheel.
8: Use the rubber mallet to gently tap on the Compressor Wheel end of the Turbine Shaft to remove it from the center section. It should not take much force to pop the turbine out of the center section.
9: Remove the Backing Plate Bolts and remove the Backing Plate. You may need to tap it lightly with the rubber mallet to remove it.
This is what you should be looking at now: (See photo below)
View of the journal bearings (gold color) held in by 2 snap rings (front & rear)
Bearing Center Section – This one still has the 270-degree Thrust Bearing Installed.
Removing the Bearings
10: Use your pick to simply pull the thrust bearing off of the anti-rotation pins. This shouldn't take much effort at all to do.
11: Using the snap-ring pliers, remove the small snap-ring that holds in the journal bearing from the front of the center section.
12: Use your pick to remove the journal bearing, being careful not to scratch the bearing bore of the center section.
13: Remove the rear snap ring. Be very careful with this one as it could potentially fly off of your pliers and get lost in the center section. If this happens it will be very difficult, if not impossible to get out! I don't mean to scare you. Just take your time and be very careful.
14: Repeat this process on the back of the center section
15: Remove the Piston Ring from the turbine shaft. It is at the back of the shaft near the turbine. You will need to use the ring pliers for this. (This is why it is good to have the “convertible” snap-ring pliers)
STOP:
At this point your bearing center section should be completely disassembled. Now it is time to check some things. First do a visual check of the of the bearing bore and turbine shaft. You are looking for scratches or other damage. If you see any scratches, run your finger nail over them. If you can feel them you will have to have your turbocharger machined back smooth or the rest of this rebuild is pointless. This is why you don't necessarily want to buy your rebuild kit ahead of time. Another set of oversize bearings will set you back another $20 if you end up needing them.
You will also want to use your caliper to check the following: (Refer to Chart Below)
Specifications:*
Part Minimum Maximum
Bearing Bore Diameter 0.6220 0.6223
Compressor Wheel Bore Diameter 0.2498 0.2501
Journal Diameter (on Turbine Shaft) 0.3997 0.4000
Piston Ring Groove Diameter 0.567 0.572
Piston Ring Groove Width 0.0645 0.0685
If there is no visible damage to turbocharger, but any of these specifications are out of spec, send your measurements to whomever you are ordering your rebuild kit from so they can send the correct parts. The most likely of all these to be out of spec is going to be either the Bearing Bore Diameter or the Journal Diameter. Don't freak out immediately if this is the case as you may just need oversize bearings which any reputable shop will swap out at no extra charge.
Lastly, check for coking in the center section. This is a common problem which can be caused by not letting the car idle to cool down the turbo after a hard run or going too long between oil changes. If the coking is severe enough, your newly rebuild turbo can fail almost instantly upon startup. Look for black carbon deposits inside on the center section, especially around the area at the rear where the turbine shaft goes in. If you find ANY buildup, it MUST be removed prior to re-assembling the turbocharger or it WILL FAIL PREMATURELY!
Replacing the Compressor Seal
Backing Plate with 4-piece carbon seal installed
T3's have 3 different types of compressor seal. The one-piece carbon seal, the four-piece carbon seal, and the dynamic seal. Don't worry about the one-piece seal and the dynamic seal. '83-'86 Turbo Coupes with the Garrett T3 will all have the four-piece carbon seal. You need to know this when you are ordering your rebuild kit. The four-piece carbon seal consists of the carbon seal, o-ring, an eared washer, and a spring. Get your pick out for this part.
16: Pick the carbon seal out of the backing plate, then the o-ring
17: Turn the Eared Washer until the ears line up with the tabs on the backing plate to remove it and the spring
Reinstallation
18: First install the spring with the smaller end down
19: Install the eared washer. Remember to turn it once it's in so it doesn't pop back out
20: Apply some assembly lube to the o-ring before installing it
21: install the o-ring and carbon seal
Putting it all Back Together
Before starting re-assembly of the turbo, clean it VERY thoroughly. You want to be able to eat off of it. Any contaminants left behind could cause your newly rebuilt turbo to fail prematurely. Clean Clean Clean...
22: Re-assembly is essentially the reverse of disassembly with a few precautions...
1. Use a high quality engine assembly lube on ALL bearings and sealing surfaces
2. Use Lock-Tite on all of the nuts & bolts if they don't already come with it applied. This includes the compressor wheel nut. The last thing you want is for the compressor wheel to come off and explode inside your turbo!
3. When installing the new piston ring, especially if you opted for the step-gap piston ring, be extremely careful not to bend it. Open it up just enough to slip over the turbine shaft and into the piston ring groove.
4. If you are not careful, you could bend the piston ring when installing the turbine into the center section. If this happens you can probably bend it back, but I would recommend buying a new ring as there is a good chance that it will leak. It should only take light tapping to get the turbine shaft to snap back into the center section. Just make sure everything is lined up correctly before gently tapping the turbine back into the center section with the rubber mallet. If it does not go back in easy then something is probably miss-aligned. Take it back out, check it over, make sure the piston ring is seated properly, and try again.
5. The 360-degree thrust bearing consists of 3 pieces rather than 2 with the 270-degree thrust bearing.
1. First install the beveled washer with the bevel facing down toward the journal bearing
2. Next slide the thrust bearing over the locating pins
3. Lastly insert the thrust collar into the thrust bearing
4. The Thrust bearing will only go back on one way. If you find that it will not slip over the anti-rotation pins you probably have it either upside down or rotated.
6. To properly torque the compressor nut
1. Once again clamp the turbine nut in your vice
2. First make absolutely sure all of the marks you made earlier when disassembling the turbo are all lined up!
3. Hand tighten the compressor wheel nut until it touches the top of the compressor wheel (assuming the wheel is fully seated).
4. Using your wrench, turn the nut approximately ¼ of a turn
5. The nut is now properly torqued
6. OR if you have an in/lbs torque wrench, torque the nut to 28 inch pounds. Then turn the nut with your wrench another 1/8th of a turn.
7. Either way works. Just do it whichever way you feel most comfortable with.
8. If after torquing the nut you notice that your marks are no longer lined up, remove it and try again. An unbalanced turbocharger is a bad thing!
23: Once everything is back together check it for radial clearance and axial end play. If you can scrape the side of either housing with either wheel (turbine or compressor) AT ALL, something is not right. Take the turbo back apart and double check your bore/shaft diameters and the journal bearing diameters. Neither wheel should ever be able to touch it's housing. End play should be no less than .0005 and no more than .0040.
24: If everything checks out re-install the turbo on the car and your done! (But keep reading anyways!)
Make sure the before starting up the car for the first time you get some oil flowing through the turbocharger! Failure to do so could cause premature failure! Crank the engine for 15 seconds without starting it to “prime” the turbo before starting the car. This can be done simply holding the gas pedal all the way to the floor while cranking.
*Specification information for Garrett T3 provided by G-Pop Shop (www.gpopshop.com)
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