Car value question

[bedlamite]

I'd replace the cat last. If you can get into it, shatter the guts with a screwdriver and pour it out. Yes, it will throw a code, but It will work and allow you to diagnose any other problems without destroying your new cat.

[cassandra and sara's daddy]

i use rebar to punch through a clogged cat

[Brad Johnson]

IF it's a failed cat don't just replace it and motor down the road.  Cats fail for a reason, usually an over-rich condition that overheats them and melts the ceramic.  If it truly is a failed cat that's a symtom of something else.

Brad

[French G.]

Most simple things first. The code for the Cat is generated by your O2 sensor, I had a cat code for 50K miles with no issues. Eliminate the fuel filter as a possibility first, then move to the fuel pump, then the cat. Anything other that was major wrong with the engine would have popped a code.

[Brad Johnson]

French is right, simple things first.  Failed cats are relatively rare.  There are a lot of other more common things that could easily be causing your problem.

Brad

[never_retreat]

I've gutted a cat before.
Problem is getting to it, it is part of the front manifold.
Also I had said earlier there is a reason for the demise of the cat to start with. She drove this thing with 2 dead coils for a long time.
Practically had gas coming out the pipe. I think they might finally have had it.


I'm going to try to get a vacuum gage a try to measure the pressure.

[Brad Johnson]

Just looked up your model (both in Mazda and Ford variants).  Looks like some brilliant engineer decided it would be better if the cats and exhaust manifolds were a one piece assembly.  Oh.  Friggin.  Joy.

Best price I can find is RockAuto.  $389 for the front bank, $393 for the rear.  Sure hope for your sake that it's something else.

Brad

[Tallpine]

Just looked up your model (both in Mazda and Ford variants).  Looks like some brilliant engineer decided it would be better if the cats and exhaust manifolds were a one piece assembly.  Oh.  Friggin.  Joy.

Another Better Idea from Ford 

[Nick1911]

Eww what a mess of a design.

I wonder if a competent shop could use a generic cat and cut/weld to the existing manifold?  Exhaust work... isn't exactly percision.

[dogmush]

Another Better Idea from Ford 

It actually is better.  It's more efficient, lasts longer and develops fewer leaks.

[Tallpine]

It actually is better.  It's more efficient, lasts longer and develops fewer leaks.

Until you have to replace one or both, at $800 parts to start with plus pull the engine which means you might as well drop in a new or rebuilt motor/tranny in while you're at it ...

which leads us back to the original post. :(

[dogmush]

Pardon the thread drift, I've had my fill of curmudgeonous this week.

Nope, no engine pulling. You have to pull an alternator, and move the AC compressor to one side, and then both manifolds come right off that engine.  It's a $400 manifold because it's a tubular header and cat in one piece.  They built it that way because customers demand ever increasing power and fuel economy in smaller packaging so they need an exhaust system that is relevantly free flowing and compact.  Because modern cats routinely last 150,000 or so miles the whole header is designed and built to last that long.  It's in one piece because if it wasn't it either wouldn't fit, or the added flange or ball and socket joint would add turns (lowering the efficiency) or leak over the service life (wouldn't pass emissions).

I apologize if I sound cranky, but cars don't have points ignitions and cast iron manifolds anymore.  And that's a good thing, it makes them lighter, faster, more powerful, more fuel efficient and longer lasting.  And big surprise, better technology costs more.  It's not some conspiracy by car company's to make you pay more for parts, or only hire lazy engineers. The only conspiracy is that of shade-tree mechanics that don't want to learn new techniques for working on cars.

[/rant]

All that said, it's probably not the cat.  It's actually pretty hard to kill those things, and if it were so clogged that it was killing your power that much, the manifolds would have been cherry red, and the engine would probably have overheated due to exhaust heat staying in the heads.  Pull the plugs and post pictures to see if it's running rich or lean.

[Tallpine]

Nope, no engine pulling. You have to pull an alternator, and move the AC compressor to one side, and then both manifolds come right off that engine.

Well, then I guess you could change the back spark plugs while you're in there 

[dogmush]

Yep.  You gotta pop the upper intake. 8 bolts and 15 min.

[never_retreat]

I pop all the plugs on the front to check the compression. They were all even and  nice colored. They are at a .065 gap so well worn, I have a set of platinums here for the car I'll put them in at the same time.
I'm going to try the disassembly tomorrow.
I called a couple of shops they all are charging 3 hours of labor and between 700-1000 for the cat. No thanks I will at least try this my self to start. I have no problem paying for 3 hours of labor but not 2-3 times the price for the part.
I can get the cat for just under 400 bucks locally and I still have a NAPA to stop by and chat with. If I go in and a certain employee is there I get the shop rates on parts.

If this thing is that farged up I probably won't be able to blow through it once its off.

Its not like I don't have the tools but sometimes when I can't see the part I get a bit intimidated.

[Brad Johnson]

I'd spend $35 on a fuel pressure test guage first.  Make absolutely sure that's not the prob before throwing a bunch of time at disassembly.

Brad

[never_retreat]

Well after spending and hour removing the intake to get to the fuel rail to check the pressure, it looks like for decided to omit the test port. bastards.
I pulled the o2 sensor that is just down stream of that cat and the car runs fine, put it back in and runs like crap.

I think either the down stream cat or muffler is the cause of the problem now.
Time for a quick lunch and I'm getting the blue tipped wrench out and removing some exhaust parts.

[Nick1911]

Time for a quick lunch and I'm getting the blue tipped wrench out and removing some exhaust parts.

Mmm, exhaust; the easy way.

[CNYCacher]

Well after spending and hour removing the intake to get to the fuel rail to check the pressure, it looks like for decided to omit the test port. bastards.
I pulled the o2 sensor that is just down stream of that cat and the car runs fine, put it back in and runs like crap.

I think either the down stream cat or muffler is the cause of the problem now.
Time for a quick lunch and I'm getting the blue tipped wrench out and removing some exhaust parts.

So you need a new O2 sensor. . .

[never_retreat]

So you need a new O2 sensor. . .

No the o2 sensor was still plugged in I just removed it from the hole. Once removed the exhaust had somewhere to go.

I just tore everything out from the y pipe back, the rear cat is shot. Can't even blow air through it with the air gun.
I'm going to replace everything else since its all pretty rusted out. The whole exhaust is cheap and that cat is about 200 bucks.

[CNYCacher]

No the o2 sensor was still plugged in I just removed it from the hole. Once removed the exhaust had somewhere to go.

I just tore everything out from the y pipe back, the rear cat is shot. Can't even blow air through it with the air gun.
I'm going to replace everything else since its all pretty rusted out. The whole exhaust is cheap and that cat is about 200 bucks.

Awesome.

[Brad Johnson]

If you removed the downstream sensor, that's AFTER the cat.  That tells me your muffler has collapsed internally or there is a huge pinch in the exgaust somewhere. If it was the cat it would still run like crap because it would still be stopped up.

Brad

[never_retreat]

If you removed the downstream sensor, that's AFTER the cat.  That tells me your muffler has collapsed internally or there is a huge pinch in the exgaust somewhere. If it was the cat it would still run like crap because it would still be stopped up.

Brad

You missed that a bit. There are 3 cats, one on each manifold and one back on the pipe. The o2 sensor was after one of the manifold cats. That was the one that I thought might be bad.

[Brad Johnson]

Oh, okay.  Well, that means that the pre-sensor cat is likely okay.  If it was the pre-sensor (manifold) cat then you should have seen no change when you opened up the sensor bung located between it an the post sensor cat.

I take it to mean that there is a single cat in the exhaust somewhere after the y-pipe.  That should mean there is a single connector at the y-pipe/cat junction.  Two bolts to drop it.  If you don't have ramps you can do it the redneck way by driving both wheels on one side up onto the curb.  That should give you enough room to wiggle under and drop that connection.

(*edit to add*
Just looked it up and it is indeed a single connection after the y-pipe.  See diagram below.)

If it's the rear converter then you just caught a HUGE break.  Rock auto shows two undercar direct-fit units available - Walker ($188) and Eastern ($149).  I looked under the Ford Escape parts list.  The same Walker part number, 53389, is also listed under the Maza Tribute parts list.  The Eastern part number, 30411, isn't list under Mazda, but if the Walker part works so should the eastern as both are direct-fit replacements for the same application.

*edit to add*
Found this vehicle-specific parts breakout over on RockAuto.
(Walker part numbers)





I'd still be careful and check the muffler and resonator.  It's still somewhat more likely for one of them to have collapsed internally than it is for the cat to have failed to the point of being clogged.

Brad