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How to Replace a 7.3L GTP38 Turbo Center Cartridge

Split Time

Bruce W. Smith
Aug 14, 2017
Photographers: Bruce W. Smith
When the turbo of a 16-year-old F-350 service truck at Mobile Diesel Service went south, the owner of the Oregon repair shop had the same decision to make as many of his Ford Super Duty customers who face similar situations: order a remanufactured turbo or repair the old one.
A remanufactured replacement would take at least a couple of days to arrive, cost about $800 for the turbo, and take the truck out of service for three to four days, costing the company more money. The other alternative, replacing the center cartridge between the turbo’s inlet and outlet, would cost less than $500, and it’d be back on the truck by the end of the day. It was an easy call.
Fortunately for owners of the venerable 7.3L turbodiesels, the Garrett GTP38 is a simple turbo to repair, and companies such as RiffRaff Diesel Performance offer a new center assembly, perfectly balanced, that makes such a job a breeze for any shop’s diesel tech.
Photo 2/15   |   RiffRaff Diesel Performance’s Garrett GTP38 center cartridge comes as a complete assembly, balanced and ready for installation. RiffRaff offers an optional billet compressor wheel for $180 that quickens spool-up, stops surge, and increases power.
RiffRaff’s turbo center cartridge is factory drop-in for ’99-to-’03 model years (the company offers a similar kit for the earlier models as well.) The kit also has the replacement O-rings for both the turbo and pedestal, along with new turbo mounting bolts.
While the turbo is on the rebuild bench, those who want to eliminate surging, add a little more power, and get faster spool-up might consider swapping out the stock compressor wheel for RiffRaff’s Gen2 billet compressor wheel ($179). RiffRaff says the new 4/4 fin wheel design, and its lighter mass, add about 17 hp to a stock 7.3L, and the crew will swap the wheels for free.
Mobile Diesel Service’s Ruben Villalobos swapped out the centersection of the bad GTP-38 in less than 45 minutes—and left the stock wheel in place. The photos show the ease of this rebuild.
Photo 3/15   |   A small pick works well to pop loose the E-clip that secures the wastegate actuating rod to the lever on the EBPV housing. No need to remove the wastegate or the EBPV housing.
Photo 4/15   |   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.
Photo 5/15   |   The new Garrett GTP38 center cartridge (left) is a factory replacement from Garrett with new seals, bearings, and rotating parts—all balanced for simple drop-in replacement.
Photo 6/15   |   We remove the 8mm 12-point bolts that hold the centersection to the turbine housing. To make the job easier, it’s highly recommend to squirt all the bolts with a good penetrating lubricant, such as PB Blaster, and let them soak for an hour before disassembling.
Photo 7/15   |   A light tap with a soft hammer will probably be needed to separate the center cartridge (left) from the turbine housing. The old centersection can be set on a shelf to collect cobwebs, because it’s being completely replaced.
Photo 8/15   |   Use a piece of fine emery cloth to lightly sand and thoroughly clean the mating surface where the new center cartridge will attach to the turbine housing. Hit it with brake cleaner and compressed air when done.
Photo 9/15   |   Ruben spread a very light coating of RTV sealant around the inner mating surface of the turbine housing to ensure a tight seal when the two pieces are slid back together.
Photo 10/15   |   Drop the new center cartridge into place and torque the four 8mm 12-point bolts to 15 to 17 ft-lb per RiffRaff’s specifications. The housing and center cartridge only fit together one way.
Photo 11/15   |   Ruben installs a new compressor housing O-ring, which doesn’t come with the center cartridge kit. It’s a $6.50 option worth having on hand when you do this job.
Photo 12/15   |   The old compressor housing is reinstalled and the 8mm 12-point bolts are torqued to 15 to 17 ft-lb, just like all the other 12-point bolts. Then the wastegate rod is reconnected to the lever on the EBPV housing.
Photo 13/15   |   The next-to-last step is installing the O-ring for the compressor housing inlet, which comes with the new center cartridge.
Photo 14/15   |   The last item of the cartridge replacement is installing both the upper and lower pedestal O-rings that come with the kit. These old O-rings are a common source of pesky oil leaks on the 7.3L diesels.
Photo 15/15   |   Better than new and ready to go back on the 7.3L. A 45-minute turbo “rebuild” that’s as simple as they come.

Sources

Riffraff Diesel Performance
866-446-3360
http://www.riffraffdiesel.com
Mobile Diesel Service
541-459-8939
mobilediesel.co

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