Finally, Diesel Vehicles Problem Solved

Tierra Del Sol offers many types of auto repair services. This post is for those of us who own diesel vehicles, in particular pickups, and the problems most associated with ownership of one of these vehicles.

It is important to note that diesel engine powered trucks and cars are generally much more expensive to repair than their respective gasoline-powered brethren. The trade-off being that much more torque is usually produced in a diesel engine and at a much lower RPM than the gasoline version, generally speaking of course.

While both gasoline and diesel engines apply similar principles of combustion, there are some pretty exclusive differences in how they achieve that result. For example, gasoline engines use spark plugs to ignite fuel-air mixtures where their diesel counterpart only uses a highly compressed air-fuel mixture – the air-fuel mixture ignites without spark plugs or any external source of ignition because of the heat generated by the compression. 

Both require cooling of the exhaust stream to reduce pollutants into the atmosphere. With today’s strict EPA emission requirements, manufacturers are using EGR to reduce these temperatures in the combustion chamber to reduce out flowing excessive emissions. 

What is EGR and how does it work? 

EGR is short for “Exhaust Gas Recirculation”. Here’s a general description of what happens. Some exhaust gases are routed through a designated pipe and injected into the pre-combustion air-fuel mixture. The already burnt exhaust gases no longer contain oxygen molecules and this inert gas, once introduced into the pre-combustion air-fuel mixture, deprives the combustion process of some of the needed oxygen to burn hot. 

Most EGR Coolers are also cooled by coolant flowing around the coolers exterior passages to cool the already hot exhaust gases passing through the center of the cooler which then gets injected into the pre-combustion air-fuel mixture. The end result is cooler combustion temperatures that emit fewer emissions. 

Diesel pickups that operate on our roads daily come into our auto repair shop frequently with engine OIL & EGR Cooler problems. The rest of this article specifically addresses the OIL & EGR Cooler problems and ultimately what causes those problems.

Diagnosing the OIL & EGR Cooler Problems

Let’s say you have a check engine light on and ask Tierra Del Sol Automotive to diagnose what caused the light to come on for you. And further, let’s assume the code is a “Cylinder Contribution” code indicating one or more cylinders on your engine are contributing less to the overall workload of the engine as compared to others. 

One of our first checks is to inspect inside the intake manifold. In most cases, we see it loaded with wet black carbon buildup. This is a sign that the EGR cooler might be leaking coolant. On many of these engines, the EGR Cooler is a radiator style cooler that uses engine coolant flowing through passages around the cooler to cool the exhaust gases as they enter into the combustion chamber.

The reason for this buildup is due to coolant leaking out of the cracked EGR Cooler and mixing with the exhaust gases that are being used to dilute the pre-combustion air-fuel mixture. This creates a sludge-like coating that attaches to the intake and runners that feed the cylinders the mixture. This sludge can build so thick, it can slowly choke, or deprive the cylinders of the correct air-fuel mixture. This results in lower cylinder contribution and the other cylinders need to carry the demanded load of the engine. 

What causes the EGR Cooler to crack? 

The Engine Oil Cooler comes into play as a contributing cause to EGR Cooler cracks. The Engine Oil Cooler is similar in design and uses engine coolant to cool the engine oil as well. Generally – and typically due to lack of routine oil changes – the dirty oil passing through the engine Oil Cooler leaves deposits (caused by the excessive heat buildup in the oil) that formulate and eventually choke off the oil flowing through the cooler. This results in higher engine temperatures and a heavily taxed cooling system that is continually trying to reduce the engine oil temperature but simply cannot keep up and overheats as well. This excessive coolant temperature causes the EGR Cooler to crack thereby introducing coolant into the intake mixture and creating the sludge. 

It is important that we understand that this is only one of the causes for this scenario to play out. There are other issues that can contribute to EGR failure as well. One being electrolysis. 

What is Electrolysis?

Electrolysis occurs in the cooling system coolant whereby small amounts of electrical current builds up in the coolant and causes it to act acidic in nature. Acidity degrades the coolant and causes corrosion buildup in the cooling system. This can cause blocked passages in the EGR Cooler and cause cracks as well. 

Without going further in-depth, the main problem is normally due to a lack of required maintenance.

The Importance of Proper Maintenance

Lack of proper maintenance often leads to a very expensive repair. In the case of our scenario, this usually means the Oil Cooler, EGR Cooler, and EGR Valve requires replacement. On top of those costs, the intake manifold is usually sent out to be “Hot-Tanked” which removes all the internal buildup inside the manifold restoring it to near new condition. 

In rare cases, the removal of the cylinder heads may also be required. This is required when the cylinder head intake runners also fill with this buildup. When this happens, we must send out the cylinder heads for “Hot-Tanking” along with the manifold. 

Keep Your Diesel Vehicle on the Road and Out of the Repair Shop

We can guarantee you that our Tierra Del Sol Automotive technicians prefer that you stay on top of our recommended maintenance schedules to help prevent these problems from occurring in the first place. You can avoid many time-consuming, difficult, and expensive repairs to your diesel vehicle with proper maintenance.