How to Clean 6.7 Cummins Turbo Without Removing [Effortlessly]

Over time, carbon and other deposits will accumulate on the turbo’s compressor wheels and in the housing, reducing efficiency and causing a loss of power. Cleaning the turbocharger is an important maintenance task that can help extend the life of your 6.7 Cummins diesel engine. 

But how do you clean 6.7 Cummins Turbo without removing it? Here are the steps to follow when cleaning a turbo without removing it:

  • Warm up the engine
  • Cautiously disconnect the inlet pipe to access the turbo
  • Spray the turbo cleaner while revving the engine
  • Idle for 5 minutes
  • Perform short revs to sling out loosened particles
  • Reconnect the pipe and take a test drive

Ready to optimize your 6.7 Cummins Turbo again? Read on for an elaborate process of cleaning it while still mounted. 

How to Clean 6.7 Cummins Turbo Without Removing?

Cleaning the turbo on a 6.7 Cummins diesel engine is an important maintenance task that can help improve performance and longevity. Over time, carbon and soot buildup inside the turbo can cause reduced power and efficiency

While removing the turbo gives the best access for a thorough cleaning, it is possible to clean it to some degree without complete removal. Doing an in-frame cleaning avoids the time and labor of disconnecting exhaust piping and other components. This method allows for the basic cleaning of carbon buildup inside the housing and wheels. 

Of course, removal will always allow for deeper cleaning, but an in-frame method can help in a pinch or for less extensive cleaning needs. If you want to clean 6.7 Cummins Turbo without removing it, here are the steps to follow:

Park your vehicle outside

It’s best to clean the turbo outside rather than inside a garage. When spraying cleaner and revving the engine, particles will be expelled from the exhaust. Parking outside minimizes cleaning needed later and allows debris to be blown away rather than accumulating inside. Outside also provides better ventilation, which is important when working around an operating engine.

Gather supplies (turbo cleaner, gloves)

Ensure you have the proper supplies to clean safely and effectively. Use a purpose-made turbo cleaner chemical designed for the job. Wear protective gloves as the engine will be hot, and contact with discharged particles or fumes should be avoided. The turbo cleaner spray penetrates the internals to dissolve deposits, while gloves prevent burns and excessive soiling.

Warm up the engine

Before starting cleaning, driving the vehicle for 10-15 minutes is necessary to warm up the 6.7 Cummins engine and turbocharger fully. This annealing process helps the chemicals penetrate more deeply once spraying begins. It also prevents condensation that could form if spraying a cold unit. Be sure both are up to operating temperature for maximum cleaning ability.

Disconnect the inlet pipe

Locate and disconnect the turbo inlet pipe after the MAF sensor with tools. Do not disturb other components, and cover openings to prevent debris entry. Disconnecting here allows the direct introduction of cleaner into the compressor side of the turbo during spraying. Be ready to reconnect securely once cleaning is complete.

Spray the turbo cleaner

Liberally coat all accessible internals of the turbo housing with the cleaner through the open inlet pipe. Short sprays are best to avoid flooding. Revving may cause briefly increased smoke, but let the engine return to idle between applications. Fully saturating with cleaner is critical for fully dissolving deposits.

Idle the engine for 5 minutes

Once the turbo is coated internally with cleaner, let the engine idle undisturbed for 5 minutes. This allows the chemicals time to break down carbon deposits with the turbo at operating temperature. Resist the urge to rev prematurely so the cleaner can dwell and work on the internals. The idle also helps circulate cleaner throughout before driving.

Rev the engine

After idling, perform 8-10 quick revs to 3000 RPM and release abruptly. This agitates the turbo and helps sling loosened particles out of the turbine and compressor housings. Smoke may increase briefly but subside as the process is repeated. Revving energizes the cleaning action. Avoid extended high RPMs that could damage components.

Reconnect the inlet pipe

Double-check the inlet pipe O-ring or gasket and mating surfaces for leaks. Firmly reconnect the pipe to its pre-cleaning position and secure it with any necessary fasteners. Covering openings is no longer needed once cleaning is complete. Reconnection restores the turbo system to normal operating configuration.

Take a test drive

With all connections intact, take the vehicle on a 20-30 minute test drive to evaluate results. Drives at varying RPMs and loads will fully exercise the newly cleaned turbo. Watch for any new smoke or noises that could indicate a remaining blockage. Pull over immediately if any issues arise before driving further.

VIDEO: How To Clean A Turbo On A Diesel Without Removing

The video below shows you the above 6.7 cummins turbo cleaning steps in action. Keep in mind, the turbo getting cleaning is not a 6.7 Cummins Turbo. However, the steps are quite similar. You should be able to follow along.

What Are Most Common Signs 6.7 Cummins Turbo Needs Cleaning?

The 6.7 Cummins turbo is known for its power and durability, but like any engine component, the turbo can diminish in performance over time if not cared for properly. So, how will you know it is time to clean your 6.7 Cummins Turbo? 

Loss Power

One of the earliest signs that a 6.7 Cummins turbo needs cleaning is a noticeable loss of power or decrease in vehicle performance. As the turbocharger becomes clogged with carbon buildup, it is less able to compress and deliver air to the engine efficiently. This lack of airflow hinders combustion and causes the engine to produce less power. The truck may feel as if it has lost a cylinder or more. Acceleration decreases, and the vehicle is less responsive when passing or merging.

Low boost pressure

The turbocharger produces boost pressure, which is the elevated air pressure delivered to the engine. As a turbo becomes dirty and inefficient, it cannot generate the optimal amount of boost pressure. This may be detected by monitoring an OBD-II scanner for boost pressure readings outside the normal/specified range. 

Alternatively, the lack of boost may be felt through slower acceleration and decreased power. Over time, consistently low boost suggests cleaning is needed to restore full turbocharger functionality.

Excessive black or blue smoke from the exhaust

When carbon and other deposits restrict airflow and insulate heat inside the turbo, it can cause increased exhaust gas temperatures and fuel residuals. This leads to an imbalanced air-fuel ratio that produces thick black or bluish-grey smoke pouring from the tailpipe. Heavy smoke is a clear sign the turbo is becoming clogged and in need of cleaning before further damage occurs.

Higher exhaust gas temperatures

As carbon collects inside the turbo, it hinders the efficient mixing of exhaust gasses with intake air. The poor flow and insulation effects cause exhaust gas temperatures to rise above healthy levels. Elevated exhaust temperatures place undue stress on turbo components and engines. Continued driving with excessive exhaust heat may accelerate turbo degradation or lead to other issues like melted hoses/wires if left unchecked.

Engine runs roughly or misfires

As carbon deposits accumulate inside the turbocharger, air and fuel delivery precision can be affected. The imbalances this causes often result in a noticeably rough engine idle or misfires under load. The engine may develop a mild knock or shake as boost pressure and air flows become inconsistent. Over time, the rough running gets worse, and the dirtier the turbo gets. Cleaning is needed to restore smooth combustion.

Strange noises are coming from the turbo area

A telltale sign that often can’t be ignored is odd noises emanating from the turbocharger. Carbon buildup can interfere with turbine movement, causing a distracting droning or whistling sound. Worn bearings might produce a grating or scraping noise. Loose or damaged parts may even knock. Since turbochargers normally operate silently, any unfamiliar noise warrants inspection. The source is usually debris that cleaning can remedy.

Oil leaks from the turbocharger

Over time, carbon and sludge can inhibit proper lubrication in the turbo-bearing housing. They may also erode seals faster than normal. The first evidence is usually oil leaks appearing around the turbo. Cleaning helps remove contaminants, allowing seals to function as intended again. However, leaks could also mean damaged seals requiring repair to prevent loss of oil pressure.

Check the engine/service engine light on

The engine computer relies on proper turbo function for emission controls and performance. Issues like fluctuating boost or exhaust back pressure trigger diagnostic trouble codes (DTCs). Commonly, codes related to air system faults will illuminate the malfunction indicator lamp on the dashboard. Scanning tools can identify which DTCs point towards turbo cleaning needs to clear codes.

Also read:

Why Do Turbochargers Accumulate Deposits?

Most drivers might not know this, but the 6.7 Cummins Turbocharger requires maintenance just like any part of the engine. But why? After all, it is not exposed to much dirt or debris. How does it get dirty? How does it accumulate deposits? Well, there are several ways, including:

Insufficient Lubrication

Lack of sufficient lubrication to the turbocharger’s moving parts is a major cause of failure. The turbo relies on a constant supply of clean engine oil to lubricate and cool the bearings and shafts. If this oil supply is interrupted, restricted, or insufficient, metal-on-metal contact can occur within seconds, leading to rapid wear and damage. Ensuring adequate oil pressure and flow to the turbo at all times is critical for its longevity.

Foreign Material In Oil

Debris entering the engine oil can also negatively impact the turbo. Items like dust, dirt, or unburnt fuel can act as abrasive contaminants in the oil supply system. Over time, these foreign particles will score away at bearing and shaft surfaces, undermining their integrity. Maintaining clean oil and an effective filtration system is important to prevent foreign objects from reaching the turbocharger and causing wear issues.

Diluted Oil

When engine oil becomes diluted, its important lubricating properties are reduced. Contamination from coolant, fuel, or water thinning out the oil compromises its ability to properly adhere to moving parts and form an effective boundary film. Running on diluted oil leaves components with less protection, increasing wear as metal surfaces interact during operation. Proper oil changes and maintenance ensure oil quality and viscosity remain ideal.

Operational Temperature Extremes

Erratic or prolonged operating temperatures outside optimal ranges can damage turbocharger components. Exposure to excessively high temperatures, such as during extended high engine rpm operation, quickens the wear of bearings and other parts. Sudden thermal cycling from very high to very low can also induce stress. Maintaining consistent, moderate operating temperatures optimizes turbocharger component longevity.

Over speeding

Allowing a turbo to spin far above its maximum intended rpm, such as during an acceleration where wastegate/boost pressure control fails, puts tremendous stress on the unit. Bearings and shafting are most at risk, as over-revving increases centrifugal forces that the components are not engineered to withstand. Routine inspection and maintenance help prevent issues that lead to overspeed scenarios.

Excessive Boost Pressure

The turbocharger produces positive air pressure to boost engine performance. Too much boost pressure strains components and degrades their life. Issues leading to abnormal spikes in boost include wastegate or compressor failures. It’s important to monitor boost levels and address any concerns before pressures become dangerously high. Keeping the system operating within its boost pressure thresholds prevents accelerated wear.

Leaks Into The System

Any leaks that allow unmetered air or exhaust gasses into the turbocharger housing upset the delicate internal dynamics. Compressor or exhaust leaks degrade turbo efficiency and potentially allow debris entry. They also introduce thermal and pressure variances the system is not engineered to withstand. Identifying the root cause of any leaks and making prompt repairs is essential to maintaining structural integrity.

Exhaust Gas Recirculation System Issues

Issues like clogged coolers or leaking piping disrupt proper exhaust gas recirculation into the engine intake with an EGR system. This causes the turbo to perform outside ideal operating parameters and thermal loads, potentially inducing premature failure. Regular EGR system maintenance and monitoring for faults helps the turbocharger function as designed.


Maintaining a clean and efficient 6.7 Cummins turbocharger is essential for optimal performance. Signs that cleaning needs to be done include loss of power, low boost pressure, excessive smoke, higher than normal exhaust gas temperatures, engine running roughly or misfiring, strange noises, oil leaks, check engine/service engine light on. Cleaning with a turbocharger cleaner can dissolve deposits, restore power and prevent undue stresses. Properly lubricated parts, blocking foreign materials in oil, correct pressure and temperatures, avoiding overspeed and leaks, and maintaining oil quality are all important for keeping the turbocharger clean.

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