Replacing the cats

My 96 Windstar has several codes regarding the cats . P04020 and P04030. I was wondering how hard it is to replace these yourself The car has 168k miles and they have never been replaced. Also,
what is a good source for the parts?

HI
a DIY'ers choice is to change the whole Y pipe. I've attached a link to Wiswinds photos from when he did the job. I believe others have too. The main problems are lack of work space and old rusted, cooked on fasteners. As to where to buy, I'd look at rockauto.com.

Good luck



http://rides.webshots.com/photo/1291096027011220610mzvEni

I have had my Walker "direct fit" unit on for several years.
It was not a fun job.......as no exhaust work is fun.
I soaked the threads of the nuts that go onto the exhaust manifold studs for a good while before doing the job.
I still ended up wrecking one stud.......about $4-5 at the dealer.
Use a wire to hold up the front end of the flex unit...that connects to the back end of the "Y" pipe assembly.......it goes from the "Y" pipe to the muffler.
If you let the flex pipe dangle....it will damage the brading.
I had to buy 2 bolds and nuts for the flex pipe to "Y" pipe connection......as my original "Y" pipe had studs....but the replacement did not.....had holes to put bolts in.
That is no big deal to do.
I was able to move my oxygen sensors from the old to new.
Use extreme care in keeping the wires on the vehcile labeled as to which sensor that they connect to.
It can be a real rat race to figure it out if you connect the sensors up to the wrong connector.

The "Y" pipe is all 1 unit......including both catalytic converters.
That takes you from each exhaust manifold.....to the cat's and back to the front end of the flex pipe.

The BEST replacement is a OEM unit from FORD.
For the '96 3.8L, they list at about $1600.
You can get them for just over $1200.
The Walker direct fit unit is much less expensive.
I got mine through Rockauto.
I have been told that Walker is about the best of the aftermarket units.

I rememer a post by another member who bought the walker unit and took it to a shop that charged him $100 to install it.
I would have been happy to have paid $100 to have mine installed.

Thank you for the info. I am goung to look into it. What did you use to remove the sensors. Any special wrench?

Mike

Thank you for the info. I am goung to look into it. What did you use to remove the sensors. Any special wrench?

Mike

I have on a few occasions "rented" from Autozone an O2 sensor tool kit. It has a few different types of sockets to make it easier to R&R the sensor. As you will have the pipe out of the vehicle it will be easier to remove them, but you may find that having the correct tool even then will be more convenient. The kit I get at Autozone looks like this:

http://www.tooltopia.com/index.asp?PageAction=VIEWPROD&ProdID=8228

You may have to heat them up with a torch until red hot,sometimes might not come out.If the threads come out crappy,you can use a spark plug tap,18mm x 1.5.Snap On has the best oxygen sensor wrench out there and is is $85.00 if you want to buy one.It has a breaker bar handle with the oxygen sensor wrench on it.The aftermarket cats are junk on Ford products.The factory ones are better.If the nuts do not come off the manifolds,heat them up with a torch red hot too and should come out.A 15mm universal socket,deepwell needs to be used and the impact version is the best because the impact version does not bind up and chrome one does.One more thing,do not throw the old cat away.There are people that buy them and give you money for them.The metals inside the cat are what they are going for.

I tried to loosen the bolts going to the exhaust manifold an was able to but the ones leading to the flex pipe were rounding off. I may have to cut them off. Any suggestions a to ho to get them off. I tries soaking with wd40.


Thanks

If you have the luxury of having the van sit, something I never get, I'd suggest a different penetrating oil. I use PB Blaster with great success. It has a capillary action which wicks its way into the threads. Spray liberally and let sit, maybe for a day or so. Every once in a while if you can give it another shot of PB and wiggle the bolt a bit. If it's rounded off, vice grips may be your only way to grip it.

Another method if you have oxy-acetelyene is to heat the area red hot and then quench with cold water. This causes the physical bond to snap between the 2 parts. A propane torch doesn't provide enough heat to do this.

Good luck!

Piper

If you have an acetylene torch, then just burn the bolt end or nut end off. I don't have one so I've used an angle grinder ( a cutoff disc is better than a grinding disc), a sawsall, and a hacksaw. When I had to remove the bolts to the two hole flange, I slotted one of the two flanges. I can't remember if I had to or decided it was a good idea and it made it easier to remove the seized bolts. It was nice to have them for bolting things back together.

I would cut them off.....maintain the integrity of the flex pipe flange as best you can.
Remember to support the flex pipe (don't let it dangle) before you disconnect it from the "Y" pipe.

To remove the oxygen sensors, I used a "oxygen sensor socket"....
I soaked the threads with PB BLaster and let them soak first.
DO NOT get the spray up over the body of the sensor......as that can damage them.
The oxygen sensor generates a voltage from a chemical reaction.
The chemical reaction is caused by a difference in oxygen in the tail pipe (exhaust), as compared to the outside (atmosphere).
So you don't want to seal the sensor material from the atmosphere.
I would also advise against using a torch to heat up the threads of the oxygen sensor, if you don't have to.