This post is for your info—feel free to reply if you’d like.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

Here is my story… <o></o>

1996 F150, 4X2, 4.9L inline 6 (engine code Y), standard cab, long bed, automatic, a/c, 128,000 miles. I was having a clicking / tapping exhaust noise that was only heard while giving the engine some gas pedal (couldn’t hear noise during idle—in park). Took truck to favorite local shop, they did the ol’ “tranny fluid into the intake smoke trick” and had one guy plug the tailpipe while another looked underneath toward the exhaust manifold. Lots of smoke where he was looking. They said “exhaust leak” and proceeded to dig down to the exhaust manifolds and removed them both, sent them to a machine shop to have them ground flat. After three days they put it all back together and guess what…noise still there, no change whatsoever!!! (fortunately, they told me since they didn’t fix the problem they wouldn’t charge me) So, I decided to do a little research on this forum (you guys are awesome, by the way!). Found out that the 1 inch in diameter tube that runs the length of the engine and sits to the left of the valve cover on top the engine but under the upper intake manifold could be cracked. So, I took a little hand held mirror and shoved it back behind the engine near the firewall and put a spotlight on it. After some shoving and looking I saw that the last little down tube was pretty much sheared clean off – with just a casual look at it, it looked fine, but it was definitely broke, I really had to get the mirror up underneath and look at where the down tube connected to the main tube. After looking in this forum and learning the different names for this tube, i.e. “Secondary Air Injection Tube” and “Thermactor Tube” (started by looking under “Exhaust Leak”) one of the posts listed the following website http://www.pciinc.com/ and they had what I needed. Part number 412 is the “Ford OE replacement A.I.R. manifold tube” and it comes with the 6 ferrule nuts. Also part number 187 “Ford OE replacement exhaust/air check valve” The dealer wanted $246 for the main tube, $19 for each ferrule nut (X6 of them--$114) and $162 for the check valve…Total $522. From the website above I got the parts for: Main tube $42, ferrule nuts included free, check valve $12…Total with shipping $62. FYI, the website only lists up to 1994 model year…I called the dealer and verified the part numbers for both the tube (F5TZ-9B445-B) and the valve (E7TZ-9A487-B) and they are the same for 1996 model year. After six short hours I did it my self and now my truck is quiet again! Those ferrule nuts are fun to put in—not, and damn that EGR feeder pipe that runs in between the last two upper intake manifold ports. Everything is just peachy now, but now I have check engine light (code P0135 “O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)”) that I have to deal with, reset it and it comes back!!! Fun never ends.

 

I experienced the same problem but I still had to pay the charge for grinding down the manifold.

 

I now beleive I have the same issue on my similar truck. But I can't quite see through to the back of the engine with my mirror. Most annoying!

Dennis, did you actually remove the upper manifold to do this job? Sounds like you worked around it.

 

Same thing here, I bought 2- 1" galvanized plugs, removed the offending tubes, air pump tubing and hoses, bypased the air pump and bingo! A quiet exhaust.
And oh yeah, for all you air-pollution nuts, my CO and NOX output is still within limits, new cat installed w/OUT air injection. My state says 1994 and under is ok as long as limits are maintained.

 

BadderBrad,

I actually did remove the upper intake manifold as much as I could...That EGR tube that runs down between the last two manifold ports is a pain. I could not get that thing off or figure out how to work around it. So, I took out all of the manifold bolts and tied (with rope) the manifold up and out of the way --sort of-- was enough to work underneath it. I had to buy a new upper intake manifold gasket and some high temp sealant--only cost about $7 for the gasket and $4 for the sealant at Auto Zone. Because the manifold was only tied out of the way, it was a pain getting the old gasket scraped off the very back of the manifold (without letting any of it fall into the holes). I followed all the torque values and torque patterns as per the Chilton's manual. Also the ferrule nuts are a pain to get started. All in all, I'm not the biggest motorhead, (probably why it took me 6 hours) but not a bad job. Good luck

Dennis

 

Dennis,

You've been an immense help. Does your truck have A/C? The rear manifold bolt looks like access only from underneath the truck with a long extension, all because of the A/C evaporator box. Bummer! I see what you mean re: the EGR tube. Did you actually disconnect the EGR valve so as to free up the manifold a bit more?

I just hope when I pull this all down I actually find that the pipe is broken. I can't quite inspect the entire pipe. Why can't these things break up front where human beings can see? I can probably shove the kids' pet hamster in there but he's not articulate enough to report the tube's condition.

 

BadderBrad,

Yep, I have A/C...And yes, the rear manifold bolts needed a long-assed extension to get to them from up underneath--and of course, a nice long straight extension wouldn't do--had to use a short one and a long one to work around some things (don't remember exactly what it was, but remember something was in the way). I didn't disconnect/loosen the EGR valve-that probably would have given me some more room.
Keep the questions coming...I'll try to answer them.

Let me know how it turns out.

Later,
Dennis

 

If you didn't use sensor safe sealer then you probably poisoned the o2 sensor. They are sensitive to silcone contamination. I don't think you can clean them just replace it.

 

Dennis,

Don't hate me because I'm beautiful! You know, this happens to me occasionally. So I'm under the hood diggin around in there not able to see that stupid pipe all the way back. Then I fire the engine and goose the throttle cable underhood and sure enough I can hear that ticking when the rpm comes up. I've heard/had enough exhaust leaks on my header equipped cars to know what I'm hearing. Finally I shut it down dejected cuz I know I'm in for work. I figure maybe next month. That's all on Sunday (I do go to church though which may have paid off). Monday morning I get in to go to work - no more noise. Wha happen??!!??!!?? Tuesday - same deal - no noise.

Next chance I get I'll be looking for a loose hose in that entire system because I think all the bumping around in there sealed up a loose one.

This takes me back to my car repair mantra: Always look for the easiest fixes first.

Now I'm knocking on wood.

 

A code P0135 means the sensor heater circuit is open or shorted to ground. This would be because the wires were cut, the O2 sensor was badly damaged, the connector came loose, or the grounding of the sensor heater circuit got messed up. It does not indicate silicone poisoning.

The heater is just a chunk of wire that gets hot when current passes through it. It is intended to heat up the actual oxygen sensor so it will give accurate results as soon as possible. The heater turns on with the ignition. The element should be 2 to 5 ohms. You should find 12 volts present in the harness coming to the sensor.

 

I have a '95 that had the same leak. I had it replaced with a tube bought from LMC. It began leaking again after a couple of months. The part was complete junk as it leaks around the ferrule nuts where the tube goes in. I've tried tightening them, but to no avail. That's the second part I bought from those guys that was junk!

 

ive got that same problem that budfords got i didnt buy the new tube from lmc but my ferrule nut on the last cylinder is leaking its been doing it for a long time and i could never figure it out but i read this and went and looked at the truck, sure enough theres a bunch of carbon build up comin right up from the inside of the ferruke nut. think it would work to just replace the ferrule nuts? or seeing i got all apart just do the whole damn thing cuz apparently itll probably blow out the end eventuallly.