Experience with ticking under load problem

[idoticsoigpa]

This is on a 1998 5.0 V8 with the external EGR tube. I bought the X in June with 109,200 miles on it. The seller stated it had an exhaust leak, and that is what I thought it was for a long time, until I figured out it had something to do with the EGR system. It had the check engine light on when I bought it, and after purchasing a scanner, it was constantly code P0401 low EGR flow. The ticking sound would come and go, having nothing to do with engine temperature or how far I was into the drive. I took it in to a Ford dealer who replaced the EVR which regulates the EGR valve. The code went away and has stayed away, but the ticking sound was louder and was much more predictable as to when it came and went. It would always be gone when starting and driving away, whether the engine was cold or hot. Then it would appear after driving about a half mile. It also would lower in pitch if I gave it more throttle and raise in pitch backing off of the throttle. I disconnected the vacuum line from the EVR to the EGR valve and the noise went away completly. The P0401 code of course came back. I then replaced the original EGR valve with a new one from Ford, and bought a Dorman EGR tube because it had the flex feature. When installing the new parts, the Dorman EGR tube was about 1/4" to 3/8" too short. I reused the original Ford tube, inspecting it closely for leaks, and it was not carboned up inside. After assembly, the ticking noise went away on the 3 mile test drive but then came back the next day. I drove it 23 miles the next day with the vacuum line disconnected and did not throw a P0401 code. I connected the vacuum line back and decided that the ticking sound just SOUNDED like it was coming from the EGR tube. I tried an experiment and wrapped the EGR tube with 10 layers of header wrap to see if that dampened the sound any. It did, but the ticking sound is still there enough that it still bothers me. So the ticking sound is coming from the EGR tube itself, but the question is why? The only part of the tube I couldn't inspect is the orifice or restriction inside the tube between the two side tubes coming off the EGR tube that both go to the DPFE sensor. I'm wondering if a new EGR tube would fix the noise, or is something else going on that just makes the EGR tube loud. I have checked all over for exhaust leaks, even removing the heat shields on the passenger side so I could get a good look at the exhaust header. I know this noise is not normal, because I drove an identical X for 135,000 miles without the ticking noise ever happening. Does anyone have any ideas on what is going on here? Thanks.

 

[swetrid]

It is probably the egr tube, they break at the flex areas and sometimes it is hard to see. The only other issues i have seen are manifold cracks or gasket leaks.

 

[Turdle]

THe header is cracked under the heat shield area between ports 2-3. The leak will cause low egr flow.

 

[idoticsoigpa]

I think I found the cause of the ticking sound.

Cause for ticking sound finally discovered! The flaired connection point on the exhaust header is about 3/16" too short, and the tube is not making contact with the connector. The nut is just holding the tube in place above the header connector, so there IS an exhaust leak, coming out around the threads and between the nut and tube. I bought a new Ford EGR tube, hoping this would fix the ticking sound and noticed this. This explains why the Dorman tube was too short. I can tell from looking at the original tube that it wasn't making contact with the connection point like it should. It has probably been this way since the X was new and the previous owners just put up with the sound. The first owners had it about a year, and the second owner had it until 2011. I am going to see if I can get a custom EGR tube made from the two tubes I have now, making one 3/16" longer than normal. I am really hopeful that this will fix it. We'll see.