EGR Cooler Failures Nissan YD25

Nissan YD25 EGR Unit Failures

IDENTIFICATION OF ISSUES

Increasingly there has been seen a number of issues regarding cylinder head failure and overheating with the Nissan YD25 Engine. 

Upon inspection of these engines, it is often seen that the EGR cooler is either cracked or corroded. Much like the EGR coolers in Ford Ranger and Mazda BT50 Engines, EGR cooler failure often goes unnoticed until it is too late.

An Important Part

Exhaust Gas Recirculation (EGR) coolers are an important part of the exhaust system. The are used to cool the exhaust gasses before they re-enter the intake manifold. This is to ensure reduced combustion temperatures which in turn reduces the creation of nitrogen oxide. 

This is particularly pertinent in turbo diesel engines where exhaust gasses are often very high, so the EGR helps to remove the heat from the gasses and transfers it ot the engine coolant. It can reduce temperature from 800C to 200C or similar. When considering the size of the unit (roughly 30cm long) that's an awful lot of heat to be removed. 

YD25 EGR Failures

It's often the case that the YD25 EGR coolers split or corrode around the flanges that are each side of the coolant fittings. Given the high temperatures of that area, the coolant tends to evaporate before showing any visible signs of leaking. Also they can fail internally which means you'll never see any sign of coolant leak. 

Testing for Failures

Testing the part for failure can be done a few different ways. Technicians may remove the EGR and pressure test it. That may show some signs of failure but is not guaranteed. Another method is to fit the part to the vehicle then run it. Steam may be seen coming out of the exhaust after engine warm up, this can mean the EGR is leaking coolant into the combustion chamber. A method for testing this is then to remove the coolant pipes and plumb them together, thus bypassing the EGR. If the steam stop, this may mean the EGR is faulty. 

The fitment of a new EGR will almost always solve the issue. 

For vehicles with active EGRs it's imperative to continually check the coolant levels regularly. If there is a coolant drop, it may be the EGR cooler. Test it along with the rest of the coolant system to ensure no futher damage.