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Diesel Emission Systems and the Future! Part 1- EGR Systems

Hey guys! It’s been over a year since I did an informative blog since we’ve been so busy at work but I’m back!! If you’ve purchased a new diesel since 2003 (Duramax 2004.5, Cummins 2007) then your engine is equipped with an emission control system. Today I’m gonna be looking at diesel emission systems in Powerstroke, Duramax, and Cummins engines but many if not most other manufacturers use very similar emission control systems. Emission control systems reduce emissions that exit the exhaust in order to prevent environmental damage from NOX, soot particulates, CO2, sulfur dioxide, and other emissions related to diesel fuel combustion. I do not claim to be a legal professional or an expert on governmental regulations but before 2003 the only state that had diesel emission regulations was California but for simplification let’s start looking at 2003 model year vehicles. The EPA passed regulations starting 2004 model year requiring diesel vehicles to reduce their emissions. There had been previous alterations to the diesel fuel itself to lower sulfur in order to cut down on sulfur dioxide emissions but the 2004 changes required making changes to the engine itself. The answer to these new regulations in 2003 for Ford/Navistar was an EGR cooler and valve in combination with an oxidation catalyst (a type of catalytic converter). An EGR cooler is a device that has coolant flowing through it and exhaust from the engine (before turbo) flowing through it. The coolant cools the exhaust to where it is cool enough to be mixed with fresh air from the turbo and reintroduced back through the intake. An “intake throttle” was also used in conjunction in order to cut off some of the fresh air so more of the exhaust can be introduced. This “recycles” a portion of the exhaust causing the emissions to be greatly reduced.

This is a picture of the EGR system flow.

This is a picture of the EGR system on a 6.0 Powerstroke engine.

Duramax engines also introduced EGR around the same time with early LB7s gettting EGR for California emissions but all Duramax engines received EGR systems beginning in 2005 with the LLY. The Duramax has the same style system with an EGR cooler and an EGR valve but the Duramax did not use a fresh air throttle assembly.

This is blown-up pic of an LLY system. Very similar to 6.0 Powerstroke but proven to be more reliable.

Common EGR failure points 2003-2007:

  1. EGR valve- Powerstroke and Duramax. EGR systems tend to be very dirty since soot from the engine is constantly flowing through the EGR cooler and when the valve opens this soot enters the intake manifold and will come into contact with oil residue from the crankcase ventilation system and create a black sludge that develops. This causes clogged sensors, clogged coolers, and eventually will cause the EGR valve to stick. When an EGR valve sticks it basically opens the floodgates for your exhaust which now flows straight into the engine and is no longer utilized to spool the turbo. This causes loss of boost pressure and LOTS of black smoke. EGR valve failures are VERY common in these and all EGR engines.

  2. EGR cooler- Powerstroke-common Duramax-uncommon. EGR cooler failures are very common in Powerstroke engines and are one of the 2 major causes of headgasket failures in 6.0 Powerstrokes. The Powerstroke system is unique in that the EGR cooler gets the coolant it needs from the oil cooler in the 6.0 engine. The problem with this is that the 6.0 oil cooler is very prone to getting clogged and causing the EGR cooler to be deprived of correct coolant flow. This causes the EGR cooler to overheat and rupture. When the EGR cooler ruptures coolant will flow into the exhaust and may damage the turbo. If the EGR cooler leak is very intense then coolant can flow up to the EGR valve and when the valve opens, coolant can flow into the intake causing a hydro-lock condition (which can damage engine/headgaskets). Blown EGR coolers on 6.0 Powerstrokes normally cause LOTS of white smoke and steam coming from the exhaust pipe. Duramax EGR cooler failures are pretty rare but can occur and will cause lots of white smoke and coolant loss as well.

Heres a pic of a 2004 6.0 Powerstroke with a blown EGR cooler. There was about a gallon of coolant in both exhaust manifolds!!

Fixes for common failures:

  1. EGR valve. There are no upgrades to available EGR valves in the Duramax and Powerstroke. Ford does sell an EGR “shield” that installs below the EGR valve and helps prevent oil vapors from soaking the valve.

  2. EGR cooler- There are multiple solutions for EGR cooler failures in both the Duramax and Powerstroke. The early 6.0 EGR coolers used large rows internally and are very rare to rupture. The 2004 and up coolers used a radiator row style design (see below pic) and are very common to fail around 100k miles. A common practice is to install an EGR delete kit which bypasses the cooler and valve and requires programming to the ECM to tell the engine to stop looking for these emission devices. The problem with this solution is that it is ILLEGAL. Bottom line. Another option is to replace the cooler with a cooler from These guys modify these coolers and beef them up and also throw in a LIFETIME warranty. Very good product and will last.

Below is a pic of a stock EGR cooler vs a Bulletproof diesel cooler. Pic property of Pawlik Automotive

You may be wondering how Cummins got by without an EGR system and the answer is…they didn’t. Cummins achieved their goals with “in-cylinder EGR”. Cummins changed the camshafts in 2004 to have a profile that would actually close the exhaust valve earlier than before and this would hold in exhaust longer causing an EGR effect. They also introduced a 3rd injection with the fuel system as well. They were no longer able to achieve this after the 2007 EPA regulations and thus EGR was introduced in 2008 with the 6.7l Cummins.

Thanks for reading guys stay tuned for Part 2!!

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