There are four key signs of a bad EGR cooler. White steam or smoke at the exhaust. Lowered coolant level with no leaks. External coolant leakage. Check engine light. If you notice any of these four problems, getting your vehicle checked out right. away is a good idea.
One or more of the following repairs can fix the P0404 code: Replacing the faulty EGR valve. Cleaning the carbon buildup in the EGR temperature sensor. Replacing the bad EGR pressure sensor. Cleaning the blocked EGR pipes. Replacing the damaged catalyst in the exhaust. Repairing the damaged vacuum lines to the EGR valve.
Jul 29, 2016. #2. Quite possibly, yes. The only way I have ever seen an EGR cooler fail is it blew coolant into the intake and it did so pretty suddenly and pretty bad, like a Batman smoke screen bad. There is no "pressure" in the exhaust of the EGR cooler that would overcome the pressure in the cooling system, just enough pressure to overcome1. This was a 140,000 mile car. 2. Its engine was destroyed because of a design defect that was unaddressed, not because of high miles or old age. The thing with old and well-known engines is you can get to know and anticipate their problems, including possible fatal ones, and address them. This is a well-known Achilles heel with these engines. Worn Valve Guides. Oil starvation is a common problem on 351 Clevelands which can cause the valve guides to receive inadequate amounts of oil and therefore wear down more quickly than they normally would. If the guides are excessively worn the valves can get off-track and close against the seat at a slight angle, eventually leading to cracked . 78 77 260 372 320 255 91 344