Diesel help’s crystal ball
Now we’re nearing to the end of Winter, we still witness the issues covered in this article well into spring. In the automotive workshop it can be difficult to predict and plan your workload months ahead. Whether it’s servicing or off the street diagnosis, to see through a crystal ball the common faults may seem unrealistic. Not for Diesel Help Australia. With a subscription base of more than 230 members throughout Australia and New Zealand, our dedicated diesel only technical library continues to expand beyond 200 technical bulletins. Each job logged is followed up until we get a result. All the success stories are catalogued and eventually become a technical bulletin. I love it when a member says- I don’t need to call you, the bulletins have helped us immensely.
Since we began providing diagnostics assistance, Diesel Help has established several trends. One our winter faults technical bulletin TB1192-egr-cooler-restriction/ to assist the technician to pinpoint the problem before it causes major complications. A popular winter symptom is difficult starting and poor performance issues and often is related to the intake and exhaust systems.
How do I determine this?
Diesels are a thermal combustion engine therefore during the warmer months a diesel tends to operate better. We have found less carbon build up in the EGR and intake systems occur in warmer climates, whereas in colder climate several factors come into play havoc with diesels. Many operators have been known to have the vehicle remain at idle for a long period whether it is to keep warm or just for love of the engine, idling away for no apparent reason.
To operate the heater and if you have the luxury of heated seats, in many vehicles the engine must remain running. A diesel engine idling for extended periods in winter will have twice as much carbon build-up in the intake system, especially within the EGR cooler. In our experience, this has been found to be predominately worse on diesel engines that endure products down the intake. Switching off the EGR operation prevents anything passing through the cooler and results in the worse cases of blockage.
When this carbon eventually restricts the intake/EGR system of a diesel, the symptoms can feel like a fuel starvation problem. This buildup of carbon can also cause the EGR valve to stick open as mentioned in my previous articles article.
A simple system to diagnose and no need to rob the diesel of its EGR. If you’re not an EGR bandit, please skip to Passage B. If you are an EGR bandit and you’re still reading at this point, then read Passage A.
Passage A
I say this passionately as a fifth generation diesel mechanic and more than 30 years of diagnosing diesels. Please focus on the long-term gain, not the short-term band aid. If you’re not that keen to work on diesels then while you’re at it, just rip the diesel out and fit an electric engine. This way you won’t have anything to complain about other than boredom and nothing to work. OR benefit from continued diesel work and a successful outcome for you and your customer. Now please feel welcome to continue to Passage B.
Passage B
Symptoms: Low power until engine reaches between 2500 and 3000rpm. When the turbo kicks in, it throws your head back with excessive force or often referred to a similar feeling like a two-stroke motorbike hitting the powerband. Other symptoms include excessive black and white smoke, surging, engine starts and stalls, engine hunts or runs uneven idle. In most cases no fault codes are present. If any fault codes are present, they may include P0401 EGR flow insufficient. Failure/issue: Restricted EGR cooler
Diagnosis and/or early detection of the fault: Request your customer to leave their vehicle overnight for full assessment including cold engine start observation. Sometimes a restricted EGR cooler demonstrates rough running and excessive white smoke during cold start up. Confirm the design and location of the EGR and EGR cooler. Some manufacturers use an EGR bypass whereas some don’t. An EGR bypass can assist with reducing emissions at higher engine revs when the vehicle is at cruising speed and the engine is not under load. The bypass also assists with warming up of the engine when cold, thus also reducing emissions.
The EGR cooler bypass often uses a vacuum operated actuator. To assist with diagnosing, it’s possible to manually change the direction of the exhaust gas flow either via the cooling vanes section or completely