OE Exhaust Questions

[jtison]

Oh boy. I've got a hole in the muffler, time to replace it. As long as I'm back there, I'm thinking about doing an entire catback system -- I'm certain (3rd owner of this '94 XLT) this is all original exhaust. AFAICT, the system from the cat forward to the manifold doesn't leak, and it passed its last emissions inspection (January '05) with flying colors.

The muffler doesn't look like a "standard" muffler ... there appears to be a heat shield or something attached to it ... it has a bunch of latitudinal ridges. True or false? All the OEM replacement mufflers I find on the 'Net look standard: plain old flat sheet metal, normal elliptical shape. Hrmm. The Maremont replacement mufflers say to reinstall the OE heat shields ... this is gonna be quite a mess if what I'm looking at is indeed the heat shield(s): it's badly corroded. Any advice/ideas? (If there's really a requirement for a heat sheild, how/where do I go about finding it and installing it?)

The most important question I have is the OEM exhaust pipe width from the cat flange back. I put my caliper on it, and it reads 2.158" OD (outer diameter) -- that's an odd size. Would this size of pipe be considered 2"? It's quite possible that all the corrosion on that pipe might be adding to the observed diameter.

The next question I have: I'm sure there are plenty of others on this board (as usual, thanks be to you!) with experience and advice about what to do about catback systems. I'd really like to find something stainless steel and as low-backpressure as possible. Suggestions? (PS: I don't weld, but I'd like to do as much of this myself as I can)

TIA, folks. This board is great

 

[SkanlaxJMO]

the pipe is actually 2.25 inches.

 

[jtison]

Corrosion's pretty bad, huh?

Thanks! (man, that was fast!) Looks like I've lost 0.10" to rust already ... there were actually narrower unbent parts of the pipe

 

[Tony H]

No welding necessary.
Never saw a ribbed Muffler as you describe.

The pipe just after the Cat. is fairly thick, you may be able to start at that point instead of at the Bolted on Flange.

 

[LXNavajo_94]

thats exactly how mine was done just cut it off at the pipe after the cat and then added the new section on after that. of course I took it to a muffler shop didnt have time to do it my self

 

[Anime]

The OEM stock muffler on the Ex's was pretty big and clunky, and if you have a standard oval muffler with a heat shield on there, chances are it was a replacement for the stocker. I've replaced the muffler on my X quite often, since the water from the cat tends to rust out the lowest part hanging down. They stopped putting the heat shields on some of the aftermarket ones a few years ago, since the mufflers tended to rust at the spot welds holding the heat shield to the muffler. You don't need any heat shields on the muffler.

The stock pipe should be 2 inches, but there are some systems that use 2.25 inch pipe.

My best suggestion for a bolt-on OEM catback system is from Walker. You can get their systems from any Advance Auto Parts or Napa. Advance charges less. They make a Premium Quiet-Flow muffler thats about $80, but it has a lifetime warranty, so if you save your receipt, you can get a new muffler every time the old one rusts out. I've replaced the one on my X about 5 times so far, saving $$$. The muffler is quiet, but flows well and pretty much all you can ask for as a stock replacement. You can get the cat-to-muffler pipe, the gasket for the cat-to-pipe seal, and the muffler-to-rear exit pipe from Walker, too. Expect to spend about $150 on the whole thing. Get two 2 inch exhaust clamps, and perhaps new flange bolts if you need them (the Ford ones sold in the red Help! containers at Advance or Autozone work perfect, $6 each). The system bolts up pretty well, but you really need to make sure the pipes fit into the muffler when you're still at the store, since sometimes you'll get one that was made to the wrong size. You really need to raise the truck up with a jack and lower the rear axle and possibly disconnect the rear sway bar on the right side after removing the spare, in order to have the room to remove the old rear pipe (since it will be rusted to the old muffer, and still hard to slide out even if you saw it off). Once the old stuff is off, bolt on the new front pipe, slide in the rear pipe, then put the muffler up there and fit it together until its on the hangers right and nothing hits. Works great, hard to beat for the price and warranty.

Also, Walker makes a performance DynoMax muffler and rear pipe for the 93-94, if you wanted something like that. Just sub in the Dynomax muffler and Dynomax rear pipe for the OEM Walker units.

 

[EMG7895]

The one with the heat shield is the stock one, I also need a new one as mine has a broken baffle inside that makes a nice rattling noise at low rpms.