Egr valve stuck open on mp8

[Roger Naeger]

The egr valve stuck open on my 2014 Mack with an MP8 engine. The engine sounded like it was ready to explode from exhaust pressure. Did this do any damage to the engine? I’ve never heard an engine sound like this!!

[41chevy]

With the engine is cruising, the EGR valve is supposed to open to allow the carbon dioxide in the exhaust to cool the combustion chamber. If the EGR valve jams open, exhaust fumes are being fed into the engine at all times. This will cause poor acceleration and rough running, because the excess exhaust fumes are depriving the engine of oxygen. Because there is insufficient oxygen, there’s too much fuel, so the unburnt fuel starts spewing out of the exhaust as black smoke, especially when the engine is at idle. THe excess fuel will also "wash" the cylinders and can cause major wear issues. Fuel consumption  wlll rise substantially.  Due to a lack of oxygen , the engine sometimes starts to misfire, sometimes seriously and might produce an unusual metallic rattle or knocking when the engine is under load.

If the engine is left in this condition for too long, the engine life will be shortened considerably. In the worst case this problem may cause melted pistons and therefore engine failure. The valves in the cylinder head may also begin to stick due to being heavily coated with carbon.  So free it or replace it ASAP.  Paul

[Roger Naeger]

Thank you, Paul

The engine was only at an idle when it did this, i’ve Just never heard an engine have so much pressure in it like that. 

[mp8_macky]

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