2003 Grand Marquis LS Exhaust Manifold

[pcmos]

Unfortunately the rear top most stud on my driver's side exhaust manifold has rusted and sheared off for some reason. I discovered the problem because of an audible exhaust noise in the driver side footwell area. The missing bolt is causing an exhaust leak at the back of the manifold where it bolts to the engine block. I can feel that the top of the sheared stud is flush with the manifold flange which gives me hope that if I remove the manifold I'll have about 1/4" of stud left to grab back there. I might even be able to tack weld something onto it to twist it out.

I'm mostly curious to know if anyone can give me some tips on removing the EGR tube from the manifold. The location seems virtually impossible to reach with any combination of crow foot sockets, wrenches, extensions or swivels. I'm assuming I'll need to remove the steering shaft to begin with, at least that should make removing the manifold bolts easier. I'm just not sure how to get at the stupid EGR fitting. How would this be done in a dealer or workshop?

[way2old]

Do you havee a 4 valve engine? If not, the EGR tube in on the passenger exhaust. It may be easier to remove the converter assembly to give more room to loosen the nut. More than likely you will break other studs off. You might want to soak them with a good quality penetreating oil a few times before you try to remove them. Good luck.

[pcmos]

No, this is the 2V 4.6L standard engine. The EGR tube is definately located on the driver's side just rear of the manifold ports, but on the top of the manifold oriented vertically. I've successfully loosened all of the other studs without any problems. I have only to tackle the EGR fitting now. I don't see any way to get at it from underneath as the hexagonal flats are positioned above the plane of the firewall. Even with the downpipe and catalytic converter assembly removed, it doens't seem that it would provide better access.

I agree that torquing the EGR fitting could strain the manifold studs and cause the front studs in particular to be broken in tension. I intend to loosen the front studs and tighten the rears to oppose and alleviate some of the strain from torquing the EGR fitting. The manifold might tend to simply peel right off the engine given enough torque on the EGR fitting.

I was curious to know if there might be some well-known trick for undoing the EGR fitting. Perhaps I will try running the engine and getting it extremely hot before applying torque. I have a decent adjustable wrench, unfortunately the hex on the fitting is 26mm, bigger than all of my crow foot sockets. My plan is to bolt an extension bar to my adjustable wrench to get more leverage. Removing the intermediate shaft for the steering might give me more room to turn the wrench as well. The rest of the job appears to be relatively easy. My task is only made a bit more daunting given the fact that I don't have access to a lift.

At the moment I'm working on thru drilling my harbor freight adjustable wrench to attach a 1/4" flat steel bar to provide me more leverage. I'll post the results. I'm confident that if I can get the EGR fitting loosened, the rest of the job will go pretty well. There is plenty of room to allow me to get the broken stud out. I'm guessing these manifold studs are strained during heavy acceleration as the engine rotates in its mounts, I plan to make sure my engine mounts are performing adequately so as to avoid further damage.

[pcmos]

I finally completed the exhaust manifold repair tonight. Unfortunately it was a massive effort that required all sorts of improvisation and even a drill guide template fabrication. The broken stud turned out to be fractured in multiple locations inside the bore. After removing the part that was protruding from the head, there was another section remaining inside the threaded hole. I had to fabricate a drill guide template from heavy steel plate to guide a left hand drill bit straight into the hole. I decided to use a left hand drill bit to remove the broken stud because easy out tools tend to snap off. Easy outs are usually made from high carbon steel and if they break off inside the hole, they're virtually impossible to drill out. Another advantage of the left hand drill bit is that it drills forward when it is rotated counter clockwise. The counter clockwise rotation of the drill bit usually eventually causes the broken stud to rotate out of the hole on its own without having to drill all the way through it. Thankfully this is what happened, but only after I fabricated a guide plate template to guide my bit straight into the hole. When I tried to drill the broken stud out free hand, I ended up with an off-center hole and started to chew up the aluminum threads in the head. I should also mention that I had to purchase a close-quarters drill at harbor freight because a normal drill wouldn't fit between the frame rail and the head surface. A pneumatic angle drill or even a standard pneumatic drill might have worked, but the cheaper ones tend to have much higher chuck speeds that make them tough to control in a situation like this.

After getting the broken stud drilled out of the head, I chased the threads with an appropriate M8x1.25 tap. Before installing the manifold with 10 brand new studs and nuts, I scrubbed the gasket surface on both the aluminum head and the manifold with medium grit emory cloth. I used a pneumatic die grinder with 3M roloc discs to further polish and clean the gasket surface on the manifold itself. Use of the die grinder would not be appropriate on the aluminum head as you could do significant damage to the head surface by removing too much material.

Unfortunately I had to spend $30 at the dealer on the catalytic converter flange studs because none of the aftermarket stores had them in stock.

In general the removal of the down pipe which includes both catalytic converters entailed removing two nuts from the catalytic converter flange studs as well as two bolts and nuts at the rear flange. All four pieces of hardware would not budge until I brought the engine up to it's normal operating temperature. Even after heating everything up to take it apart, I ended up breaking the catalytic converter flange stud protruding from the manifold.

Literally every bolt and nut that needed to be taken apart was seized in place. In order to remove the O2 sensor and catalytic converter studs from the manifold I had to bolt the manifold to a 3/4" 2x4 sheet of plywood in my garage and use a 3 foot breaker bar with a MAPP gas torch. The O2 sensor was actually removed with an O2 sensor socket and breaker bar without the use of heat from the torch.

The EGR tube connection includes a threaded plug that is threaded into the exhaust manifold, as well as a flare nut which is tightened down onto the threaded plug. Upon disassembly, the plug came out of the manifold, the flare nut remained seized on the plug. I had to fully remove the EGR pipe by disconnecting it at the EGR valve. After I had the EGR tube off the car I used a 3 foot breaker bar with a 1" socket to separate the flare nut from the threaded plug. I then reassembled everything with anti-seize compound.

If anyone has any questions about various steps of the repair process I can post specific answers, I'd have to go on for about three pages to describe everything. I can also take pictures of my drill guide template system for anyone curious about how I fabricated the guide. I've been borrowing a MIG welder system from one of my friends for the past month or so to get some other work done on the car. Unfortunately the welder would be required to replicate my guide template fabrication, as well as a steel chop saw, drill press, angle grinder, shop press and a full set of indexed cobalt drill bits. I used 3/16" x 3" steel plate from home depot and a 1/4" x 3/4" steel spacer from lowes to build my drill guide to drill out the broken stud. I also cut my 1/4" left hand cobalt bit in half and welded on a new shank to make it shorter so that the combined length of the bit and drill would fit into the available space. Frankly, without this guide system I would have been forced to remove the head from the engine to get the broken stud out. My goal was to avoid the extreme hassle of removing the cylinder head to remove a single exhaust flange stud.

After doing a test drive of about 40 miles I feel confident that the repair worked and all of my abnormal exhaust noise is gone. I sincerely hope that I don't have to repeat the same repair for the passenger side manifold at some point in the future. I debated whether I should try to replace the studs on the other side, but decided against it fearing that I'd break one off trying to loosen them. I might as well wait for it to happen naturally, lol. After completing this repair I would certainly understand if a dealer or mechanic charged as much as 1500 bucks to get it done. I was very lucky to only have to deal with one broken stud on the driver's side. Any other location would have required significantly more work and possibly the removal of the cylinder head.

[pcmos]

Here are some pictures that I posted on webshots documenting my exhaust manifold repair project. Included in the album are a series of pictures showing the steel drill guide template that I fabricated to remove a broken stud. I've included some notes on some of the pictured labeled "annoted".

Exhaust Manifold Repair Project & Stud Removal:

http://rides.webshots.com/album/575691364aIATQX

[way2old]

Thank you pcmos. I am going to stick this so it may help another user. Good job. way2old

[30fords]

Originally Posted by pcmos

Here are some pictures that I posted on webshots documenting my exhaust manifold repair project. Included in the album are a series of pictures showing the steel drill guide template that I fabricated to remove a broken stud. I've included some notes on some of the pictured labeled "annoted".

Exhaust Manifold Repair Project & Stud Removal:

http://rides.webshots.com/album/575691364aIATQX

Great post. this will help someone i'm sure. some advice with a problem i just went through would be to check the shift cable where it attaches to the lever on the transmission. mt rusted off at the worse time. you might want to check it especially if you live where they put down salt.