Saturday, July 13, 2013

How to remove an exhaust manifold from a 5.4L Ford F150

   The problem announced itself when my truck was under load. It was coming from the lower right (passenger side) part of the engine. It sounded like the "putt..putt..putt of an exhaust leak at the rpm of engine and only when accelerating or going uphill. I took off the wheel well cover to investigate. To take it off:
1) Remove five 7/32" hex head sheet metal screws. These are reachable with a 1/4" drive ratchet or a wrench.
2) Pop off 4 panel fasteners, mostly toward the right front of the cover.
3) Pull two wiring harnesses from the engine side of the cover. They are held in by attached panel fasteners.
4) Now loose, the cover can be pulled off by bending it over a wheel mount bracket near the middle.
  There was a black sooty mark on the engine at the back of the manifold. I ran the truck with the cover off and I could feel the exhaust escaping from the rearmost exhaust port.
The left port is leaking. Note the extreme rust on the bolts/studs
     The upper four manifold nuts and studs resemble a blob of rusted metal. The challenge of this job is in removing these eight nuts and studs. On the underside, the two middle nuts and studs looked OK, but the end two were quite corroded.
     1) Jack up the right front tire using the regular jack that came with the truck. Remove the wheel and lower the frame onto substantial supports. I used a couple of railroad ties. That's my preferred material for load bearing. Don't use auto jack stands to work under the truck.
    2) Optional, remove the starter to make access to the under bolts must easier. I have a post for that.
    3) Once the starter is out, the bracket for the starter wiring harness can be removed. It's in the way of getting cutting tools in there for the bolts.
   4) Remove the flange bolts, where the exhaust pipe bolts to the manifold, with a 15mm socket and breaker bar. I had to cut them off. I used a Sawz-All (reciprocating saw) on the upper bolt and a Dremel cutting wheel on the lower one. I finished it off with a hacksaw. Here is a video of the preliminary disassembly:


   5) Time to get at the upper manifold nuts and studs. Staring at them isn't going to get it done.  I didn't even try to spin off the upper nuts. They aren't nuts anymore, just blobs of rusted metal. I decided to cut them along the length of the stud with an angle grinder or a Dremel tool with a reinforced cutting wheel.Then I turned the weakened nuts off with a channel lock pliers or found a socket that would fit. On one of them I used a hammer and chisel to get the reduced nut off. On two of the four, the nuts caught on the studs and they came out with them. All right! Two of the studs remained in the head and would have to be removed when the manifold is pulled off.


   6) Remove the under-side nuts. On my truck they weren't as badly rusted  Try using a socket and a breaker bar first. One of them turned out for completely with a 13mm deep well socket, a three inch extension bar and 3/8" to 1/2" adapter and a 1/2" breaker bar. On another the complete nut somehow came off intact without removing the stud.

Use a breaker bar to turn out the underside nuts...if possible

    The two outside ones proved to be more difficult. On the front-most one I used the Dremel with cutting wheel, holding it parallel to the manifold with me above. I was able to cut enough off to loosen it up. The stud pulled out with this one.

It was a little tricky to take a slice out of the front most under-nut

    There is always a tough nut to crack, isn't there? On this job it was the rearmost under manifold nut. This one was corroded too badly to turn off with a socket. I had to work underneath with a Dremel tool to somehow remove enough off the nut. Eventually (several hours later) I got the nut to turn off with a small vice-grip pliers. The stud stayed in. Now the manifold can come off. A straight edge showed it was warped.

   7) Remove the remaining studs. Three studs remained in the head. Two were persuaded off with vice grip pliers.


    Notice the corrosion on the head of the leaking port. This is a good reason for not putting off this job once the manifold starts to leak. I ran the truck for a couple thousand miles after the leak appeared. Exhaust gases are extremely corrosive and if left leaking too long may eat away the head. I am going to use some cold weld to fill in the fairly shallow pits in the head.

                                Here is a video of the removal of all fasteners, except the final seized stud:

    As I said, the upper rearmost stud was stubbornly seized. I found a good article online and I tried it too: seized bolt removal tips. I tried PB Blaster and vice grip pliers and then I used a Dremel tool to square it off, so a crescent wrench could be used on it. It wouldn't budge. I even fabricated a wrench to match the squared off stud. Nope. Nothing worked. It would have to be cut off, drilled out and extracted.
   This is exacting work. Get it wrong and the head may need to be repaired or replaced. I had never drilled out a broken or seized stud on a vehicle before so I took my time...and got it out cleanly.  I don't want to bore you with the details on how I managed to drill out that stud here. Every manifold removal presents different challenges, and you may not have encountered a seized or broken stud, so I made a separate post for that procedure: Drilling out a seized stud...

   Here is a video of that procedure and the concluding segment of the removal of the manifold:

      The removal of the manifold was a tough job. The installation is almost enjoyable by comparison. Here is a link to my installation post:  Installing the passenger side exhaust manifold on a 5.4L F150.

                                         Good tools for this kind of work


  1. removing mine the last few weeks...between workin OT at work and tryin to find time to work on my truck it seems to take forever....i have 3 that came right out....the other 5 are givin me fits....i have soaked them for weeks day and night in PB Blaster.....and yes it takes patience...ok tonight I actually used a sawzall to cut the mainfold into had a huge hole in it anyway.....tonight i used a tool i had bought to extract the studs..well one is to small for the tool to fit tight enuf....i tried on the same stud you drilled out and it seemed to be coming out ..but low and behold only part of it now i will be driling it it seems...the others i shall try heat and be more patient with.....I am hower having a hard time with the bottom nut 3 back from front....there is a part of the frame or a bracket blocking access to get a socket on it....any ideas? email me @ please

  2. That is really nice to hear. thank you for the update and good luck. exhaust manifold corrosion

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  4. Do you replace the header? But the other side is a bigger problem? I have both sides problem with a rust!

  5. Thanks, David. I have a similar problem and I'm debating whether to do it myself or take it to the shop. I worked on Diesel trucks and heavy equipment years ago in my 20s, and I have a technique I think you might like to know about.

    For stuck studs like the one you had, if you have oxy-acetylene, heat the stub of the stud, taking it up to cherry red for about 3-5 minutes, then let it cool. This sounds backwards but does work. The stud expands of course, and after it does so radially and gets as big as possible in that direction, it expands lengthwise. It even squashes the rust in the thread. Then as it cools, it's a bit longer and skinnier than before the heat. Do this three or four times and it is almost a matter for fingers instead of wrenches.

  6. Looks like you have a bug in your webpage. I published the above as, but it shows as Unknown

  7. After all I have read about removing the manifold,it seems to me that removing the wheel well is just as much a pain in the ass. So many things attach to it. Engine was replaced last fall so
    I don't expect a major rust issue.

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  10. Loved your video, which makes me think of this tool from Milwaukee that will blow your mind:
    Like a Dremel on steroids, plus, it will take HD wire brush tools for serious rust removal in tight places. A set of carbide die grinding bits, and you have a hand-held machine shop.