Cummins ISC Diesel Engine Turbocharger Failure

Cummins ISC Turbocharger Replacement from John Whelan on Vimeo.

This failure occurred without any notice. In the video you can see the nut that loosened off and backed right off of the turbo shaft. Once this happened it caused seizure and a large amount of oil started pumping through the intake system. The turbo bearings are lubricated with pressure engine oil so there's a big mess when this type of failure happens.

The oil did help in a way flowing into the charge air cooler and leaking out a crack in the cooler core. So replacing the charge air cooler was added to the list. Once the turbocharger was replaced with a re-manufactured unit along with the charge air cooler this engine was back in business. It's important to flush out the air piping in case debris got trapped. The steam cleaner does wonders for this type of task.

Preventing this failure would be hard to do since normal preventive maintenance does not involve removing air intake and boost piping for inspection during a service. This would take too much time so the only other clue would be poor boost performance or turbocharger noise audible to the mechanic or driver.

I hope you find this video informative as food for thought. A failure of this kind will happen again undoubtedly somewhere...somehow. It falls under the "how the hell did that happen" category. If you have a comment please state it below. I like to get feedback form readers who have gone through something similar.

 

How Diesel Engine Turbochargers Work

How Diesel Engine Turbochargers Work

Mechanic Notes:  A diesel engine is 'dead in the water' without the turbocharger. High pressure atomized diesel injection needs maximum air intake boost to operate efficiently. You'll know when the turbo is not working up to speed, the smoke show out the tail pipe will be the obvious sign.

 Mechanic Checks for A Turbocharger Problem
If you suspect a turbocharger problem and the diesel engine you're working on is a mechanical model you can check the boost pressure which should be around 20 p.s.i.

Take the reading off of the intake manifold with the engine at full throttle and full load. Hook up a line and go for a road test and make sure you get a nice heavy pull on the engine. The next step is to remove the intake side of the turbo (easier than the exhaust side) and check the compressor wheel and shaft for any movement and wear or signs of engine oil in the piping.

The air induction system includes the air filter and piping which must not be overlooked. Simple steps include checking for a restriction in the air filter and visually checking out the piping for loose clamps and perforations. The first sign of a hole in the piping or a loose clamp will be a high pitched whistle, not to be confused with the characteristic whine that comes from a turbocharger under load.

 This is a common problem and can be checked by setting the park brake (set wheel chocks as an extra precaution), foot brake on, transmission in gear and throttling up the engine RPM enough to feel a load. You'll need assistance with this test so you can look and feel for leaks.

Electronically controlled diesel engines will most likely flash a trouble code on the dash which requires diagnosis with a laptop / software. The modern day Mechanic needs software and a laptop...if you don't have these tools you're going to go down fighting.

Here's an excellent video tutorial on how the turbocharger works. Check it out!

Diesel EngineTurbochargers Need TLC

Cummins C Model Diesel Engine Turbocharger

The turbo on a diesel engine is an amazing piece of equipment that puts out thousands of rpms and gives us the boost we need to get into that perfect torque curve we need to power up a grade. You will know right away when the turbocharger is faulty. Without that charge air flowing into the intake the ratio between air and fuel will go south and heavy plumes of exhaust will pump out of your tail pipe getting some unexpected onlookers staring you down along with a huge loss of power.

This Holset Model pictured here comes with  a waste gate (the round housing top left). A boost line is connected to a diaphragm and when the pressure hits a pre-calibrated level the excess boost pressure is exhausted out at around 20 psi or higher. The compressor wheel seen here as well is driven by the exhaust turbine wheel on the opposite side, so it's a self driven unit.

This is pure genius and gives the engine the extra air intake volume to keep up with the fuel injection system. Both the compressor and turbine wheels should be checked periodically for wear on the shaft and if there is any scuffing on the turbo housing caused the blades making contact. You don't want one of these guys blowing up and debris getting into the intake.

Yamaha Bikes Going TurboDiesel!

Source: hellforleathermagazine

I guess nothing is impossible and Yamaha has filed for a patent for a turbodiesel motorcycle engine. It will be an inline 4 with an intercooler and turbocharger added on which will place the fuel tank under the seat.

I would love to see the prototype once it comes out of the factory. Listening to a diesel engine in a street bike would tempt me to buy one. I love the knock of a diesel, coming from a much smaller vehicle would be surreal. The power and torque would be unbelievable with possibly a slow take off?

Who knows, with the much lighter chassis with a bike it might take off like a rocket. Check out the link above where you can view the patent information and some interesting ideas and concepts. This is very interesting providing mechanics information that you can bite your teeth into!

HOMEPAGE

Cummins Engine Repair - ISB Model

Cummins Engine Repair on a 2002 Thomas Freightliner School Bus. The head gasket was leaking coolant from the right front corner. The first step is to unhook the battery and drain the coolant.
The Turbocharger [pictured] can be removed as a complete assembly attached to the exhaust manifold. The fuel lines are removed from the opposite side.


The Cummins 24 valve turbo diesel has 2 intake valves and 2 exhaust valves for each cylinder. The parts displayed here have been cleaned and inspected for pitting, hard surface wear and corrosion [head bolts]. Head bolts are measured for length, with a special guage provided by Cummins [usually comes with the head gasket kit].


The cylinder head itself weighs approxiamately 80 lbs. [3 Mechanics removed the head off the block manually and it's a clumsy operation!]
Here I'm using the hydraulic hoist to install the head, the only problem we encountered was the reach was not long enough on the hoist boom so I removed the front wheel to enable rolling the hoist into the engine compartment further. [An overhead hoist would be perfect for this job!]

Cummins Engine Repair involves cleaning and inspecting, especially when it comes to the block surface. Look for any cylinder scoring and cracks then run a straight edge on the block surface where only a few thousands of an inch wear is allowed. Use a .003 in. feeler guage to check the block wear.




Removing the injectors is easy once the fuel connector tubes inside the head are removed [Below]. The injectors have hold downs on top that have 2 fasteners, when removed the injector has a threaded hole on top that can be used to pull the injector out which is held in by an o-ring.
NOTE: Remove injectors before removing cylinder head, the injector tips protrude past the head surface.


The fuel connectors in the Cummins 24 valve turbo diesel have an o-ring seal and connect the fuel between the fuel injector lines and the injectors. They are tapered and have a machine fit into the injector body. The injector hold downs only install one way and index the injector in the head bore so the connector tube aligns with the injector.



I hope this basic overview has helped you get more aquainted with Cummins Engine Repair

More To Come!

Recommended: Diesel Engine Repair Manuals

Cummins Diesel Engine Turbo Failure

Cummins Diesel 'C' Models come with a Holset brand Turbocharger. The operator noticed a noise coming for the engine, it was the turbocharger compressor and turbine wheels making contact with the turbo housing.

When a turbocharger fails it's hard to guess how much damage has occurred and how much debris has gone through the system.
In this case on one of our "C" Cummins Engines the turbo shaft bearings failed and the oil which is fed from the engine under pressure entered the exhaust and intake system.





Once you get oil in the system and various particulates or even chunks from the failed turbocharger it is recommended to replace the air charge cooler as well.
This one was saturated with engine oil, we always have a rebuilt air charge cooler on hand since there has been problems with the aluminum core deteriorating causing turbo boost leakage and loss of power.

The turbocharger was sent out for repair and all the piping checked and cleaned out as required. This problem was caught in time by the operator who heard the noise from the engine as it happened.
If undetected there would have been much more damage. Once we replaced the turbo and the air charge cooler this bus was ready to go once again.

This is what could happen and most times cannot be avoided on a Cummins Diesel Engine.