Komatsu Diesel Turbocharger Guide: SA6D, PC200 & Excavator Applications

This Komatsu Diesel Turbocharger Guide is built for the mechanics and equipment owners who open a hood, find a hard-to-read data plate, and need to know exactly what turbo is bolted to their excavator or dozer. Komatsu is unusual among the big iron builders: some of its engines are Cummins blocks wearing a Komatsu badge, and some are Komatsu’s own designs with Komatsu turbos. If you buy the turbo the engine model suggests instead of the turbo on the tag, you can end up with the wrong housing, the wrong actuator, or no fit at all.

PT Turbo has been rebuilding turbochargers since 1978, and we stock both new and remanufactured units for the Holset and BorgWarner turbos used on many Komatsu machines. The goal here is to help you identify the right one before you order.

How to read a Komatsu engine model before you touch the turbo

The first thing to understand is that Komatsu engine names tell you the family, and the family tells you who likely built the turbo. Several of Komatsu’s small and mid-size engines are license-built or rebadged Cummins B-series and L-series blocks, which means they ride on Holset turbos. Komatsu’s larger own-design engines use Komatsu’s KTR-series turbos.

Here is the practical map you need in the field:

Komatsu engine	Actually a	Typical turbo family
S4D102 / S6D102 (SA6D102)	Cummins 4BT / 6BT	Holset HX30 / HX35
SAA6D107 (SAA6D107E)	Cummins QSB6.7	Holset HX35W (Tier 3); Komatsu KVGT (Tier 4)
SAA6D114 (SAA6D114E)	Cummins QSL9 (8.3 / 8.9 family)	Holset (Tier 4: Komatsu KVGT)
108-series	Komatsu (PC300 class)	BorgWarner S2-series replacements on older units
SAA6D125 (125-series)	Komatsu (PC400 class)	Komatsu KTR90
SAA6D140 (140-series)	Komatsu	Komatsu KTR110

Whatever the engine family suggests, the final word is the part number on the turbo’s data plate on the compressor housing. Casting numbers on the housings only narrow the search; one casting serves many turbos. Match the tag number, then confirm wheel sizes and A/R.

SA6D102 and the PC200 class: the Cummins 6BT turbo

The 6D102 and SA6D102 are the Cummins 6BT, the same 5.9L block that powered a generation of trucks and equipment. Many PC200-class excavators and matching loaders and dozers ran this engine, and on the mid-weight ratings it carries a Holset HX35. The four-cylinder 4BT (S4D102) uses the smaller Holset HX30.

Both are fixed-geometry Holset turbos, oil-cooled, with no vanes and no electronic actuator to calibrate. That makes them some of the most straightforward turbos in the Komatsu lineup to service. The HX35 shares its bones with the truck turbos many diesel techs already know, so parts and rebuild knowledge are deep.

Because this is a Cummins engine under the Komatsu paint, the same diagnostic and rebuild logic from the on-highway world applies. If you want the background on the HX35 and its wastegated cousins, our Cummins ISB 5.9L turbocharger guide breaks down the differences in detail.

One caution on the PC200 family: Komatsu moved through several generations and emissions tiers, and the turbo changed with them. Confirm your machine’s exact turbo by the tag before ordering, because a late Tier 4 PC200 does not use the same turbo as an early one.

Tier 4 Komatsu machines: variable geometry arrives

As emissions rules tightened, the Cummins-based Komatsu engines moved to variable-geometry turbochargers. The SAA6D107E is the Cummins QSB6.7: Tier 3 versions run a wastegated Holset HX35W. Tier 4 Komatsu machines use a Komatsu variable-geometry turbo (KVGT), while the industrial Cummins QSB6.7 is listed with a single sliding-nozzle Holset, an HE300VG or an HE341VE depending on the rating, so go by the tag on your unit.

A variable-geometry turbocharger uses a moving nozzle to change effective flow across the engine’s speed range, improving low-speed response and spool. On the Holset units the nozzle is moved by an electronic actuator that must be calibrated to the turbo it is fitted to, not to the ECM. Komatsu, by contrast, moves its own Tier 4 variable-geometry turbos hydraulically, which is a different system entirely.

The SAA6D114E is the Cummins QSL9, Komatsu’s name for the 8.3 / 8.9L family, and it follows the same story: earlier ratings on a wastegated Holset HX40W, later Cummins ratings on a Holset variable-geometry turbo such as the HE431VE, and Tier 4 Komatsu machines on the Komatsu KVGT. Our Cummins ISL turbocharger guide and Cummins QSB turbocharger guide map these engine-version splits so you can confirm which one you have.

Larger Komatsu engines: 108, 125 and 140 series

Move up into the big machines and you leave the Cummins family. The 108-series sits in the PC300 class, and the older units of that size are commonly rebuilt with BorgWarner S-series replacements such as the S2B, S2D and S3A. These are rugged fixed-geometry turbos that have proven themselves across construction and ag engines.

The SAA6D125 (PC400 class) and the SAA6D140 are Komatsu’s own engines, and they use Komatsu’s KTR-series turbos: the KTR90 on the SAA6D125E-5 and the KTR110 on the SAA6D140E-5. Do not expect a Holset or an off-the-shelf Cummins turbo to fit these. The right replacement is defined by the number on the unit, not by the engine badge.

Common turbo failures on Komatsu machines and how to read them

Construction and mining turbos live a hard life: dust, long idle periods, heavy load cycles, and oil that works overtime. Most turbo failures trace back to the oil supply or to debris, not to a turbo that simply wore out. A turbocharger rides on an oil film (or on bearings fed by that same oil), so anything that interrupts clean, pressurized oil ends the unit quickly.

Use these symptoms to point your diagnosis in the right direction before you condemn the turbo:

Symptom	Likely cause	Check first
Low boost, slow spool, black smoke	Boost leak, up-pipe/manifold leak, or stuck-open vanes/wastegate	Charge piping, boots and clamps, exhaust joints ahead of the turbine
Overboost, high drive pressure	Variable-geometry nozzle stuck closed	Actuator function and calibration on VGT units
Blue-gray smoke, oil in charge pipes	Often crankcase ventilation, not always the seal	Breather, air filter, oil level, oil drain condition
Noise and shaft wear	Imbalance or bearing wear	In-and-out shaft play you can feel, wheel contact with housing

A couple of field notes that save turbos. Some side-to-side rock at the wheel is normal on a journal-bearing turbo with no oil pressure; condemn it for in-and-out play you can feel or for wheel contact with the housing, not for any movement at all. And if a compressor wheel has shed metal, the intercooler must be replaced, because debris in the fins cannot be reliably flushed out and will travel on into the engine.

On the variable-geometry units, resist the urge to move an electronic actuator’s arm by hand. The gears are self-locking and break. Unbolt the actuator and move the vane lever instead, and calibrate the actuator to the turbo with the proper service tool after fitting.

New versus remanufactured turbos for Komatsu equipment

For most Komatsu applications you have a choice between a new replacement and a remanufactured turbocharger, or sending your own core in for our in-house rebuild service. Here is how they compare.

Factor	New	Remanufactured / rebuilt
Availability	Depends on model; some supplied from warehouse	Broad; most rebuilds ship in 3 days or less
Core	None required	Core return within 30 days on reman units
Fit	Exact to the part number	Your exact unit back, balanced on a VSR
Warranty	12 months, unlimited mileage	12 months, unlimited mileage

Because current pricing is model-specific, we keep it on each product page and on our turbo rebuild price list. If you cannot find your exact Komatsu turbo number, send it to us and we will match it or quote a rebuild; our contact page and (909) 824-1020 get you a real answer. Fleet customers can call or send a list of their tag numbers.

Frequently Asked Questions

Which turbo does a Komatsu PC200 excavator use?

Many PC200-class machines run the 6D102 / SA6D102 engine, which is the Cummins 6BT, and on the common mid-weight ratings that carries a Holset HX35; the four-cylinder 4BT uses an HX30. Later emissions-tier PC200 machines moved to different and sometimes variable-geometry turbos, so always confirm by the part number on the turbo’s data plate rather than the machine name.

Is a Komatsu turbocharger the same as a Cummins turbo?

On the Cummins-based Komatsu engines, yes: the S6D102 is a 6BT, the SAA6D107 is a QSB6.7, and the SAA6D114 is a QSL9, so before Tier 4 they ride on the same Holset turbos as those Cummins engines; Tier 4 machines use a Komatsu variable-geometry turbo. Komatsu’s own larger engines, such as the SAA6D125 and SAA6D140, use Komatsu KTR-series turbos instead, so the engine family decides it.

How long does a Komatsu turbo rebuild take at PT Turbo?

Most rebuilds ship in 3 days or less, and we confirm the rebuild price after inspection and before any work starts. Send us the number off the turbo’s tag so we can match the right bearings, seals and thrust parts before your core arrives.