Tools & Tips
EGR Valves & Coolers
EGR Valves & Coolers
It doesn’t seem to matter who made the engine, Exhaust Gas Recirculation (EGR) circuits seem to be a common point of failure. EGR currently does the lion’s share of meeting the NOx emissions standards. Selective Catalytic Reduction (SCR) is the primary system to manage NOx emissions in the upcoming EPA 2010 engines.
A cooled EGR Circuit is made up of 2 basic pieces. The EGR valve diverts a determined amount of the exhaust gas through this circuit & back into the intake. The EGR Cooler is a heat exchanger box/radiator that cools recirculating exhaust gas before it passes back into the engine to be re-burned. The now cooled exhaust gas then mixes with incoming fresh air of the intake.
There are a couple of signs that will tell you if an EGR cooler is failing. A plugged cooler will make your bus lose about 1/3 of its power. Coolers that leak push white smoke through the tailpipe. A leaking cooler can drip coolant out of the exhaust pipes that enter & exit the EGR cooler. EGR Coolers will sometimes leak as heat builds up because the cooler has become plugged with soot and ash.
Sometimes the EGR valve becomes stuck with exhaust ash & no longer actuates properly. If this becomes pronounced, an ECU code will come up on the odometer display. The 3 part code will look like ECU 128, SId 146, & FMI 07. You will also see a yellow check engine light, feel the engine go into “De-Rate” mode & lose power. Stuck EGR Valves are caused by ash & soot build-up.
Suggestions to prevent ash & soot build-up:
A.) Work hard to eliminate unproductive idle time. Fuel is expensive.
B.) Use the cruise control switches or the “Lift Power” switch to rev the engine up to 1,000 or 1,100 RPM.
1. This will cut down significantly on soot & ash production.
2. Higher RPMs raise turbo boost pressures that help the engine push more air &
exhaust through the EGR circuit.
3. The result is a cleaner, fast flowing exhaust with less chance for particles to settle into the EGR system.
C.) Use the “Low Ash” (CJ-4) motor oils that newer EPA ’07 engines require.
1. These oils have less ash in them to create the build-up in the EGR circuit
2. If you have an EPA ’07 engine with a Diesel Oxidation Catalyst (DOC) & a
Diesel Particulate Filter (DPF), CJ-4 oil is required by the engine mfgs to
protect the DPF/DOC and to meet the emissions standards.
The same operating tips also ensure the smooth operation of your 2007 & newer buses equipped with DOCs & DPFs.
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