Cummins/Holset HY35 Turbocharger Disassembly

2003 - 2004 5.9L Cummins Turbocharger Disassembly Procedures

The 2003 to 2004 model year 5.9L Cummins employs a Holset HY35W type D turbocharger. This turbocharger model is often misidentified as a HE341, likely due to similarities between the two turbocharger models. Disassembling a turbocharger can be tedious task as years of heating and cooling cycles combined with the frequent presence of moisture typically causes the cast iron turbine and bearing housing flanges to corrode and adhere. While the following information and procedures are based on 2003 and 2004 model year Dodge Rams, the premise and basic techniques are applicable to a wide range of Cummins diesels.

Turbocharger Nomenclature & Assembly Indexing

A turbocharger assembly can be divided into three major sections:

Compressor housing - Cast aluminum housing that encases the compressor wheel. Ambient air is drawn in through the inlet (large diameter opening at its center) and is evacuated through the small diameter channel.

Center section - The center section can also be referred to as the bearing housing, bearing cartridge, or center cartridge. It houses the journal bearings, thrust bearing, thrust washer, and a variety of seals. Lubrication of all components occurs in the center section of the turbocharger, thus it has oil feed (inlet) and drain (outlet) provisions that allow engine oil to enter and exit. The center section is a cast iron component with various machined features. Some center sections are cooled by the engine cooling system; this particular model is not.

Turbine housing - The turbine housing is a cast iron housing that encases the turbine wheel and wastegate valve. Exhaust gases from the exhaust manifold enter the flanged inlet of the turbine housing and exit via large diameter opening in its center where the exhaust downpipe attaches.

Turbocharger Part Cleaning Techniques

The preferred methods of cleaning turbocharger parts, assuming the core components are in good, reusable condition, are media/sand blasting and degreasing with an ultrasonic cleaner. Media blasting can be used on the turbine housing and external features of the center section as these cast iron components are not dimensionally sensitive. Media blasting works well at removing carbon buildup and rust, particularly on the turbine housing. At no time should any internal nor rotating components of the turbocharger be media blasted, nor should any blast media be allowed to enter the orifices/cavities of the bearing cartridge or compressor housing. Such infiltration will compromise the machined surfaces of these components and ultimately lead to premature failure. Thus, the internal features of the bearing housing must be appropriately protected prior to media blasting.

Ultrasonic cleaning is suitable (and preferred) for cleaning of the remaining turbocharger parts that are to be reused. A mild degreaser that is safe for all metal types is necessary. Heated ultrasonic cleaning operations are more successful at removing thick grease/oil deposits. After removing parts from the degreasing solution, thoroughly clean with a solvent such as brake cleaner. Ultrasonic cleaning is extremely successful at removing buildup on turbine and compressor wheels prior to inspection. These sensitive, balanced components are better cleaned with this method than by mechanical means such as brushing. Once components are cleaned, they must be thoroughly inspected for cracks, defects, and indications of wear.

HY35W Turbocharger Disassembly Procedures

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HY35W turbocharger

• Disconnect the wastegate actuator hose from the compressor housing fitting.

• Remove the silencer ring from the compressor housing inlet by using 2 flathead screwdrivers to remove the large snap ring.

Removing wastegate actuator retainer

• Remove the wastegate actuator arm from the wastegate linkage at the turbine housing (single retaining ring).

Removing wastegate actuator

• Remove the wastegate actuator from the compressor housing. It is secured with (2) nuts requiring a 10 mm socket.

• Set the wastegate actuator aside.

Removing compressor housing snap ring

• Remove the large snap ring securing the compressor housing to the center section. This can be somewhat cumbersome, but a large set of snap ring pliers in addition to a large screwdriver typically works well.

Compressor housing snap ring removed

• You may need to "walk" the snap ring around the circumference of the compressor housing land in order to loosen it as they tend to bind during removal.

• Index the compressor housing to the center section so that it can be reassembled in the correct location. A scratch awl or engraving tool is recommended as the marks will not be washed off during cleaning.

Separating center section and compressor housing

• Carefully separate the compressor housing from the center section without allowing it to bind against the compressor wheel (remove straight up in direction parallel to compressor/turbine wheel shaft). Do NOT rotate the compressor housing during removal as it will shear the alignment pin.

• Remove and discard the compressor housing o-ring, if applicable.

• Index the compressor wheel to the tip of the compressor/turbine wheel shaft so that it can be reinstalled in the exact position it was removed (may affect compressor wheel balance if assembled in different position). Make your lines on the tip of the compressor wheel and tip of the shaft, NOT on the nut that secures the compressor wheel to the shaft.

Removing compressor wheel

• Remove the nut securing the compressor wheel using a 10 mm, 12 point socket (note - although less common, some HY35W models feature a 6 point compressor wheel locknut). The compressor wheel nut is left hand/reverse thread, thus you will rotate CLOCKWISE to loosen.

Turbine heel closeup

• Shaft movement can be prevented when removing the compressor wheel by holding the turbine wheel with a 14 mm, 12 point socket (note - required socket size may vary by application).

• Remove the compressor wheel from the shaft and set aside in a safe place.

Indexing center section and turbine housing

• Index the large Marman clamp securing the turbine housing to the center section so that it can be reassembled in the exact position it was removed (note - paint pen used for illustrative purposes only; this should be done with a scratch awl, engraving tool, or other means that won't wash off during cleaning). These three markings will also be used to index the turbine housing to the center section.

Removing turbine housing Marman clamp

• Remove the Marman clamp securing the turbine housing housing to the center section using a 10 mm deep socket.

Separating turbine housing and bearing housing/center section

• Separate the turbine housing from the center section. This is typically done by holding the assembly at an angle with one edge of the turbine housing resting on the workbench and hitting the housing with a dead blow hammer. Soaking the joint where the two parts mate in penetrating oil may help considerably. Some turbochargers will separate with ease while others can be extremely stubborn. Hit around the circumference of the turbine housing so that the turbine housing separates evenly and does not bind against the turbine wheel.

Removing turbine wheel and shaft

• With the center section and turbine housing separated, gently tap the shaft with a dead blow hammer to unseat the turbine shaft oil ring, then remove the shaft from the center section. Care should be taken not to scratch the machined finish of the shaft during removal. Excessive force is not necessary to remove the shaft.

• Looking into the center section from the turbine side, remove the small snap ring holding the rear journal bearing in place, then remove the journal bearing.

• After removing the rear journal bearing, remove the inner snap ring below it.

Removing oil cap

• From the compressor side of the center section, remove the large snap ring securing the oil cap.

Removing oil baffle and thrust washer

• Remove the oil baffle, thrust washer, and thrust collar located beneath the oil cap.

Removing journal bearing

• Remove the small snap ring securing the front journal bearing in place, then remove the journal bearing and the snap ring located directly behind it.

Removing oil cap seal

• Remove and discard the oil cap o-ring.

Removing oil ring seal from thrust bearing

• Remove the metal oil ring from the thrust bearing without scratching the machined surface.

Removing turbine shaft oil ring seal

• Remove the metal oil ring from the end of the turbine/compressor wheel shaft without scratching the machined surface of the shaft.

Thrust washer alignment pins

• Examine the thrust washer alignment pins; if damaged, they will need to be removed and replaced. If they appear in good condition, it is perfectly acceptable to leave them alone.

• The turbocharger is now completely disassembled and ready to be cleaned, then reassembled with new bearings and seals. See cleaning techniques/information above and HY35W rebuild guide for assembly procedures.