Intake manifolds melting

[dstaley]

Hi guys,
I'm working with my first Ford- a 2004 Taurus SES with the flex Vulcan OHV engine I bought used two weeks ago.

The original owner was not a "car guy" so he farmed out all his mechanic work. He had paid someone to change the spark plug wires, oxygen sensors, intake manifold and rear catalytic converter, however it was missing on #1 cylinder, had misfire & lean codes so I got the car cheap because it had obvious engine problems as well as cosmetic issues. The original intake manifold was in the trunk, with holes melted around the EGR tube outlet. The new aftermarket (direct fit) catalytic converter was loosely clamped in place at the rear of the converter.

Once I had the car home, I found a bad (chewed on by rodents) spark plug wire on #1 and the ignition coil pack was failing, so I took care of those and welded the rear of the catalytic converter to the rest of the stock exhaust, and also changed the O-ring seal at the bolted flange between the front Y-pipe assembly and the new cat.



It runs great now, but I'm still getting lean codes, so I took it to a dealer to help me find the rest of the problems. The IMRC O-ring and the O-ring around the PCV tube inlet were both leaking, so I ordered the IMRC O-ring and picked up a properly fitting O-ring for the PCV tube inlet. The dealer verified that my cats are not plugged- backpressure was low as it should be.

My original intake has melted pinholes around the PCV port- this is the same area where EGR gasses are released into the intake. Obviously, excessive EGR gasses are being released for some reason, resulting in excessive temperatures. I noticed tonight that inside the original intake manifold there is far more massive melting damage.



The replacement manifold appears to have the same damage. Only a couple pinholes show so far, but the interior damage appears pretty extensive from the PCV fitting hole.



You can see I patched the pinholes with RTV so that I could finish my diagnostics, but the interior melting seems bad.

Is this a common problem? The dealership insists that my cats are flowing fine- and since I have 89,000 miles on it, they really have nothing to benefit by saying they're flowing just fine (they're saturated and not really working anymore, but they are not plugged or melted).

I have ordered a new intake manifold, have replaced the EGR differential pressure sensor, the EGR valve has been blessed by the dealership, but I'm nervous that replacing the intake will just result in another melted & damaged intake- and these things are NOT cheap.

Have any of you seen this- and solved it? Have you checked the condition of your intake in this area?