Ford 7.3L Powerstroke Turbocharger Guide: TP38, E99 & GTP38 Models Explained

If you wrench on OBS and Super Duty Fords, you already know the 7.3L Powerstroke turbocharger is one of the most reliable factory units ever bolted to a light-duty diesel. But “reliable” doesn’t mean “all the same.” Between 1994 and 2003, Ford ran three distinct Garrett pedestal-mount turbos on the 7.3L: the TP38, the early-1999 E99 GTP38, and the late-1999-and-up GTP38. Bolt the wrong one to the wrong engine and you’ll fight boost lag, EBPV problems, and pedestal oil leaks all day. Here’s how to tell them apart and spec the right unit the first time.

The Three 7.3L Powerstroke Turbos at a Glance

All three share the same basic Garrett architecture: a single, fixed-geometry, oil-cooled center section mounted to a cast pedestal in the engine valley, fed by twin up-pipes. Where they differ is turbine housing sizing, wastegate setup, and the wheels inside. That’s what changes spool-up, drive pressure, and how the truck behaves towing heavy.

Spec	TP38	E99 GTP38	GTP38 (Late 99-03)
Model Years	1994.5-1997 (OBS)	Early 1999	Late 1999-2003
Wastegate	None	None	Yes (internal)
Turbine A/R	1.15	1.0	0.84
Compressor Inducer	~60mm	~60mm	~60mm
Intercooled	No (air-to-air added later)	Yes	Yes
EBPV / Exhaust Backpressure	Yes	Yes	Yes
Typical Peak Boost (stock)	~18-20 psi	~18-22 psi	~18-24 psi

TP38: The OBS Workhorse (1994.5-1997)

The TP38 came on the 7.3L Powerstroke in the “Old Body Style” trucks. It’s a non-wastegated, fixed-geometry unit with a larger 1.15 A/R turbine housing. Because there’s no wastegate to dump drive pressure, the TP38 builds boost predictably but doesn’t spool quite as quick down low as the later GTP38. These trucks were not factory intercooled, so EGTs climb faster under load, something to watch if you’re towing or tuned.

The most common TP38 complaints we see at PT Turbo aren’t the turbo itself, they’re the support hardware: worn pedestal o-rings causing oil weeping into the valley, leaking exhaust up-pipes (the dreaded donut gaskets), and a sticking exhaust backpressure valve. When you pull a TP38 for a rebuild or swap, replace every seal in the system. A fresh turbo bolted to crusty up-pipe gaskets is money wasted.

For a clean TP38 install, the Ajusa Ford Installation Kit JTC11014 covers the gaskets and seals you need and is available from PT Turbo for $46.88, view the JTC11014 kit here.

E99 GTP38: The Odd One Out (Early 1999)

When the Super Duty arrived for 1999, Ford introduced the GTP38, but early-build 1999 trucks (commonly called “E99”) got a transitional version that catches a lot of techs off guard. The E99 GTP38 is non-wastegated and uses a 1.0 A/R turbine housing, larger than the late-99 unit. It also has a different turbine wheel and pedestal oil drain arrangement than later trucks.

Here’s the critical part: you cannot freely interchange an E99 turbo with a late-99 GTP38 without addressing the pedestal, oil drain, and wastegate differences. The early trucks ran a different exhaust backpressure setup and the wastegate-style pedestal won’t bolt up the same. Always verify your build date off the door sticker before ordering. If you’re not sure which camp your 1999 truck falls into, the team at PT Turbo can cross-reference your VIN and build date, reach out here before you buy.

Because the E99 is non-wastegated with a bigger A/R, it tends to run a touch lazier off idle but holds top-end well. Owners chasing quicker spool sometimes upgrade to a wastegated late-99 setup, but that’s a parts-matching job, not a straight bolt-on.

GTP38: The Wastegated Late Model (Late 1999-2003)

Late-1999 through 2003 trucks got the refined GTP38 with an internal wastegate and a smaller 0.84 A/R turbine housing. The smaller housing spools faster, and the wastegate bleeds off excess drive pressure up top, giving a better balance of throttle response and EGT control. This is the most common 7.3L turbo on the road and the one most reman cores are built from.

The wastegate is also the part that fails most on these. The actuator diaphragm cracks, the linkage gums up, or the canister loses its reference signal, and suddenly you’ve got overboost spikes or boost that won’t build. Before condemning the whole turbo, check the wastegate actuator and the line to it. Many “bad turbo” calls on a late GTP38 are actually a $40 actuator problem.

When the center section is genuinely worn, shaft play, oil in the exhaust, or a scored compressor wheel, it’s time for a rebuild or a quality reman. PT Turbo has been rebuilding Garrett pedestal turbos for over 45 years, and our turbocharger rebuild service restores your original core to spec with new bearings, seals, and a balanced CHRA. If you need a unit on the shelf ready to go, browse our remanufactured turbochargers.

Common 7.3L Turbo Failure Symptoms and What They Mean

The 7.3L Powerstroke turbo is tough, but nothing lasts forever behind 200,000-plus miles of towing. Here’s how symptoms typically progress so you can catch a failing unit before it grenades the engine.

Severity	Symptom	Likely Cause
Early	Slight oil weep in valley, minor smoke on startup	Pedestal o-rings, worn seals
Early	Boost slow to build, lazy throttle	Wastegate actuator (GTP38), EBPV sticking, intake leak
Moderate	Whistle or siren noise that changes with RPM	Air leak or early bearing wear
Moderate	Blue/gray smoke under load, oil in intake tract	Failed turbo seals, excessive shaft play
Severe	Metallic grinding, sudden boost loss, visible wheel damage	Bearing failure, wheel contact
Severe	Overboost spikes, codes	Stuck wastegate, failed actuator

If you’re cross-shopping turbos across the Powerstroke lineup, our deeper dives on the later engines are worth a read, including the 6.0L Powerstroke turbocharger guide, the 8 warning signs of 6.0L turbo failure, and the 6.4L Powerstroke twin turbo guide. The

Cross-Reference & Superseded Part Numbers

The turbochargers covered in this article match or supersede the following OEM and manufacturer part numbers. If you are searching by part number, these are the units stocked by PT Turbo for this application:

12709901039  •  172-025-1045  •  172-784-0084  •  172-784-0092  •  172-784-0105  •  172-784-0106  •  172-784-0107  •  172-784-0147  •  172-784-0528  •  172-784-0529  •  172-784-0530  •  172-784-0532  •  172-784-0533  •  172-784-0534  •  172-784-0558  •  172-784-0561  •  172-784-0576  •  172-784-0583  •  172-784-0595  •  172-784-0600  •  172-784-0607  •  179618  •  466746-9001S  •  466746-9003S  •  478473  •  479514  •  479515  •  479519  •  479523  •  479526  •  481782  •  482990  •  49S3105502  •  53039880462  •  53039880469  •  53039880470  •  53039880505  •  53039881004  •  53039881005  •  53039887227  •  53039887230  •  53039887231  •  53039900469  •  53039900470  •  53039901004  •  53039901005  •  54359880009  •  54399880081  •  57739900001  •  57769900000  •  59001107387  •  702012-5012S  •  725390-5006S  •  725390-9006S  •  734852-5009S  •  739619-5004S  •  743250-5024S  •  743250-5025S  •  743250-9024S  •  743250-9025S  •  772441-5002S  •  777469-5002S  •  786880-5021S  •  798128-5009S  •  851824-5001S  •  851824-9001S  •  853333-5001W  •  854572-5001S  •  854572-9001S  •  854800-5001W  •  855562-5001S  •  855562-5002S  •  855563-5001S  •  855563-5002S  •  857260-5001S  •  880862-5001W  •  881027-5001S  •  881027-5002S  •  881028-5001S  •  881028-5002S  •  886195-5001S  •  888142-5001S  •  888142-9001S  •  888143-5001S  •  888143-9001S  •  889938-5001W  •  889939-5001W  •  892147-5001S  •  925330-5001S  •  925351-5001S  •  926432-5001S  •  JTC11014  •  JTC11094  •  JTC11175  •  JTC11274  •  JTC11285  •  JTC11328  •  JTC11472  •  JTC11537  •  JTC11787  •  JTC12835  •  RMN-BRG-V2S-TWN  •  RMN-BRG-V2S-TWN-GR-TO  •  RMN-BRG-V2S-TWN-NO  •  RMN-GRR-GT3-TRB1  •  RMN-HLS-H53-TRB1  •  RMN-HLS-H53-TRB2

Can’t find your number above? Contact PT Turbo — our team has been matching part numbers since 1978.

Further reading: Learn more about turbocharger technology.