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How To Rebuild a 7.3L GTP38 Turbo

Boost Renewal

Bruce W. Smith
Jul 6, 2017
Photographers: Bruce W. Smith
Oil leaks caused by failed O-rings and blown seals in the turbocharger are the most common maintenance concerns with 7.3L Ford Power Stroke engines that are starting to show their age. In any turbodiesel engine, time and heat are hard on these components, and when they fail, it can lead to bigger, more expensive problems if they aren’t addressed in a timely manner.
So when Gary Fadness, owner of an ’02 Super Duty with 215,000 miles on the odometer, was told by a tech at Mobile Diesel Service that his daily driver’s tired turbo is the reason behind his truck’s reduced power and the puddles of oil it leaves in the parking lot, he moved quickly to have the problem rectified.
Photo 2/26   |   Garrett Turbo Rebuild
The decision was now between swapping the Power Stroke’s stock Garrett GTP38 turbo for a remanufactured ’charger and having the shop rebuild it. Wanting to keep repair costs down and because the turbo doesn’t show any signs of internal damage, the Oregon businessman is opting for the latter.
Gary’s choice is actually a solid one for budget-minded owners of ’99½-to-’03 7.3Ls that haven’t been modded. The GTP38 is easy to rebuild, and companies such as RiffRaff Diesel Performance offer affordable kits that make doing the job yourself a good bargain.
RiffRaff’s GTP38 Bearing Rebuild Kit ($67) features everything needed to bring a worn turbo back to fine form, including an upgraded Garrett 360-degree thrust bearing to replace the stock 270-degree version. This upgrade provides better oiling and helps distribute the thrust load more evenly, extending the service life for the most critical area of a turbo. The kit also has the replacement O-rings for the turbo and pedestal.
Photo 3/26   |   RiffRaff Diesel Performance’s Garrett GTP38 Turbo Rebuild Kit ($67) comes with the 360-degree thrust bearing (top), journal bearings, seals, and O-rings. The RiffRaff billet compressor wheel (foreground)—which we’re using for this rebuild to quicken spooling, stop surge, and increase power—is a $180 option.
While the turbo is on the rebuild bench, it is also being fitted with RiffRaff’s lighter Gen2 billet compressor wheel ($195) to eliminate surging, provide considerably faster spooling, and add about 17 hp. Rebuilding a turbocharger isn’t a job everyone can tackle. But for those who are not scared to break loose a few bolts and follow well-illustrated instructions, doing the work yourself will not only improve a stock Power Stroke’s performance and longevity, it will do so for about half the cost of installing a remanufactured turbo.
We’re peeking over the shoulder of Mobile Diesel Service’s Ruben Villalobos as he rebuilds the Power Stroke’s GTP38. The photos show how easy it is to perform a turbo rebuild, which takes less than an hour from start to finish. It’ll be time well spent for a lot of 7.3L owners out there.
Photo 4/26   |   A small screwdriver works well to pop loose the E-clip holding the wastegate rod to the lever on the compressor housing; then the wastegate is removed and set aside.
Photo 5/26   |   The compressor housing will probably need to be given a few gentle taps with a soft hammer to pop it free after the five 8mm 12-point bolts are removed. If you’re going to reuse the compressor wheel, remove the housing carefully so the wheel fins aren’t damaged.
Photo 6/26   |   The seven bolts that secure the EBPV housing to the turbo are removed. We recommend dousing all the bolts with a good penetrating lubricant before disassembling to make the job easier.
Photo 7/26   |   The compressor wheel is removed by using pliers to hold the hub of the turbine wheel while turning the compressor wheel counterclockwise. A small impact driver works best to initially loosen the turbine wheel on the threaded shaft; then carefully spin it off by hand.
Photo 8/26   |   Four more bolts hold the center carrier to the turbine housing. A few taps with the soft hammer help knock it loose, exposing the turbine wheel.
Photo 9/26   |   With the backplate off, the wear on the 270-degree thrust bearing and collar is easily seen. These worn-out parts, and the O-ring, are all being upgraded. Pay close attention to the orientation of the brass thrust bearing before removing it.
Photo 10/26   |   The original Garrett 270-degree thrust bearing and collar (left) are being replaced by the 360-degree combination that provides better oiling and distributes the thrust forces more evenly for longer life.
Photo 11/26   |   If you pull the turbine wheel assembly out of the housing and see this, you can stop the rebuild part right here and replace the entire centersection.
Photo 12/26   |   If the turbine wheel comes out of the housing looking like this one, you’re good to resume the rebuilding process.
Photo 13/26   |   A light tap on the turbine shaft helps slide the assembly out of the center support, exposing the brass bearings and steel spacer between them.
Photo 14/26   |   The turbine shaft seal ring is removed. This piece wears and is a common cause for oil leaks. A small pick is used to get the ring out of its groove and off the shaft.
Photo 15/26   |   Ruben uses a small brass brush to clean off the built-up carbon from the shaft and seal-ring groove. Then, a scouring pad polishes the surfaces before reassembly.
Photo 16/26   |   We’re replacing the old seal ring with the larger of the two in the kit. Don’t spread the ring too much when putting it back on the shaft.
Photo 17/26   |   The center cartridge also needs to be thoroughly cleaned of carbon, both outside and in the recessed area the shaft and seal slide into. Scouring pads, a wire brush, and brake cleaner will do the trick.
Photo 18/26   |   Give all the bearings in the kit a nice soak in clean engine oil before installing. This ensures they will have at least some lubrication before the engine starts.
Photo 19/26   |   Reassembling a Garrett GTP38 turbocharger is just as simple as taking the unit apart. Start by placing the new journal bearings and spacer on the cleaned and polished shaft.
Photo 20/26   |   Look underneath the center cartridge to ensure the seal ring is centered, and then firmly press the cartridge down until you hear and feel a little “click” of the seal ring engaging.
Photo 21/26   |   Use the new bolts supplied in the kit to install the 360-degree thrust bearing, washer, and pre-shaped seal ring.
Photo 22/26   |   A trick Ruben uses to hold the seal and bearing in place during reassembly is to coat everything lightly with white lithium grease.
Photo 23/26   |   Fingers help keep the thrust bearing in place as the backplate is inserted and set on the center cartridge.
Photo 24/26   |   All the 8mm bolts that hold the turbo together are torqued to 15 to 17 ft-lb in a crisscross pattern, including these four that secure the backplate to the centersection.
Photo 25/26   |   This is a closer look at RiffRaff’s Second Generation performance billet compressor wheel with the 4/4-blade design. The new wheel is said to spool faster and reduce smoke, while providing 5 to 7 pounds more boost (about 17 hp and 38 lb-ft of torque).
Photo 26/26   |   After the compressor and EBPV housings are reinstalled and the bolts torqued, Ruben demonstrates how to use a little compressed air to push the wastegate actuator rod down so it can be secured to the wastegate lever with the E-clip.

Sources

Riffraff Diesel Performance
866-446-3360
http://www.riffraffdiesel.com
Mobile Diesel Service
877-421-3187
mobilediesel.co

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