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Trouble separating cat from muffler


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mbdd
New User

Jun 9, 2015, 10:43 AM

Post #1 of 6 (793 views)
Trouble separating cat from muffler Sign In

Hey all,

I'm repairing my 2003 Benz S430. The right-rear cat is busted and I'm trying to replace it myself. I have everything unbolted. Problem is, I can't get the flange separated. It's not a standard flange as most cars have, as one pipe inserts into another. I've tried PB Blaster, heat, nothing makes it budge. The bolts came off fine, it's just the joint itself that is stuck.

I'm thinking of going as far as using a come along to pull it out. Any advice?

Thanks


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 9, 2015, 11:04 AM

Post #2 of 6 (783 views)
Re: Trouble separating cat from muffler Sign In

Help nail down EXACTLY what this car is please - lots of choices to go thru to see what you are dealing with but think I have it. For Federal emissions and 2 WD shows this pipe I think you are fighting with........

Are you talking about the connection shown wth a clamp ("U" bolt and saddle type?)
If that's the type for love nor money will you get that apart without a torch meaning at least MAPP/OXY but better Oxy/Acet such that outside pipe will glow fast (not melt) and twist the inside one right out. This is child's play with torches if standard as shown.


OK: What to do as I know you don't have torches. I would probably try the small tank (never have as have real stuff) MAPP/Oxy set sold actually at hardware and home centers - about $60 bucks. Says they can cut steel so only needs that temp just fast but not cutting anything ---- practice on something not involved.


Other untested by me: Those chain type wrenches you wrap around assorted round things. Maybe with two and some force you could get the pipes to twist and come apart.


If I'm right at what I think that isn't a "flange" at all. It's a pipe inside a pipe so close that clamped they are like one. Heat to wild temps and fast has always been my answer for those or replace every dang thing involved. Looks basic, not DIY friendly without the tools or torches,


T



mbdd
New User

Jun 9, 2015, 11:52 AM

Post #3 of 6 (779 views)
Re: Trouble separating cat from muffler Sign In

Thanks for the quick reply Tom. This picture is close.

The joint pictured in the middle is actually a solid pipe(or welded, don't remember off the top of my head). In fact, the entirety of that picture is one solid welded piece.

The issue is at the very rear of this assembly, downstream from the rear cat. It's a pipe inside another pipe. The lip is only about 3/8-1/2" deep. There's also a graphite donut gasket inside of it.

Picture of gasket:
http://contentinfo.autozone.com/...S/wkr/31399/image/4/

The manifold is unbolted, the support bracket is unbolted(seen as the rectangular bump in the middle), and the "flange" is unbolted in the very rear. Picture of what that kinda looks like:
http://contentinfo.autozone.com/...S/wkr/31964/image/4/

It's the very rear that is stuck inside of the other pipe that I can't get out for the life of me. I do have a MAPP/OXY torch that I attempted to use around the edge of it to expand it, and it didn't seem to do much. I tried to twist it with a pipe wrench but couldn't get the leverage to really get at it.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 9, 2015, 12:27 PM

Post #4 of 6 (776 views)
Re: Trouble separating cat from muffler Sign In

OK - I see what's giving you fits. True - Original systems can be totally welded such that you need funky crap (some hack type muffler shops live on that crap - some excellent) you just cut and fake it really.


No - you can get that apart. Just keep in mind a couple things for this as it's not really "squished" into each other just tight and meant to be. Outside heated (has to be fast, meaning so fast inside part(s) don't have time to be same temp) expands and maybe with this one a careful and precise wrap with a hammer would make it let go?


Seriously, haven't tried the little (size doesn't matter in this the gas does) MAPP/OXY stuff yet so can't say how fast it is. Oxy/Acet w assorted tips is lightening fast and when I could see worth a shat could just cut out exactly what I didn't want and so on.


Principle would be the same (not tested by me) with cold like dry-ice on the inside and a whack.


There are some specific chisels that may just cut just what you want with a plain hammer that doesn't hurt what you are keeping.


Assorted tricks if you cut (even w a hacksaw if need be) off the spent pipe parts so you can get closer to mess with the tough area. More funky tools like a chisel that you can hammer to PULL with -- done that on some bearing races here and there.


If this just never ends with frustration for you and with a VERY careful look at what's there down to just this if the car can be driven to a close shop just to knock that apart it might be a choice? AYOR with that totally.


So far with the pics and what I'm guessing you have for tools you can do this. Just more fighting with it.


Do yourself a favor with exhaust stuff especially when not tossing everything in sight out use that aluminum "Anti-Seize" brush in cap stuff as the new part soon and old stuff may not be bad again at the same time and save all this grief.


Keep fighting. You just haven't hit the right spot with whatever yet and will be done with this fast after that,


T



mbdd
New User

Jun 9, 2015, 1:50 PM

Post #5 of 6 (766 views)
Re: Trouble separating cat from muffler Sign In

Thanks for the encouragement. I like the ice idea, might be able to combine that with fast heat on the outside. I just wanted to make sure I wasn't missing anything obvious before I got rough with it.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 10, 2015, 6:09 AM

Post #6 of 6 (755 views)
Re: Trouble separating cat from muffler Sign In

IMO that's a normal fuss for that type connection. It's meant to be real tight. Those bolt thru holes are pulling new stuff in tight not squishing or bending the connection of pipe over a pipe" type. Essentially if all new and tightened it would stay there without the bolts. Could be some off-norm difficulty if it's been fussed with before for any reason.


Again, just know the heat differences must be fast. If too slow both items become the same temp and just as stuck. Many a few seconds of help with a helper speeds it up like quick hold this lit torch out of harm's way so I can do this next thing instantly no fuss with putting torch out and out of the way losing time.


One more warning when new stuff ready. Make dang sure parts are in line perfectly as when tightened again and if wrong twisting that so bolt holes like up and parts are fixed where they belong is critical. They can't be left bumping other items of the car or too close to anything fuel involved.


Think I said a tap/whack with the right hammer could be the last trick at the right time or twist with tools that do that. Careful with hammer types not to bend or break anything. Use wood if need be in between or what works.


Note: When you are all done with this if another exact same thing was next to do you'd do it in minutes then knowing the exact approach that worked best.


Good luck. Silly stuff like that can be a total pest,


T







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