Prudence, my 87 Town Car

[DerekTheGreat]

"good amount of rust." For you, perhaps :P

I'll show you a good amount of rust..

[gadget73]

Torch and make the collector nuts red hot. They will come right out afterward.

[Mainemantom]

Use PB blaster, soak, let it sit for awhile, soak again. Stuff works great of rusty nuts and bolts. You can buy at Walmart, auto parts stores.
Heat also works well.

[DerekTheGreat]

I don't have much love for PB blaster or WalFart, both suck IMO. PB blaster is better than nothing, but I have had good luck with fresh or mildly used ATF or ATF+acetone though.

[Lutrova]

Several treatments of WD-40 throughout the week did the trick and freed the cat-H pipe connection. I couldn't get the car high enough to pull manifold and downpipe out together, but the extra mobility did make it easier to get to the manifold-cat bolts and pull everything out. Boy are those old manifolds heavy. Must weigh at least twice as much as the Lincoln logs.

Do these cars have pre-cats? I looked in the first chamber on the passenger side pipe and there was nothing in there. The passenger converter had been cut out and replaced at some point. Driver's side appears to be all stock, though I can't really see inside either chamber on that one.

I also noticed that bolt-on replacement converters online don't have the upper chamber, just a single converter and pipe.

[VicCrownVic]

Good to hear you got it apart. My method is cutting and/or fire, but the amount of rust I've had to deal with here is ridiculous.

In stock form these cars had two cats per side. The direct fit replacements only have one cat per side which is supposed to be capable of doing what the two did originally thanks to technological advancement (or so I assume). The single cat direct fit replacements are much easier to work with since they free up some space. Not sure if you'll catch grief in CA during visual inspection (if the inspector is sharp enough to know the original configuration), but if the exhaust sniffer inspection is all that matters then supposedly you should be fine. No clue since there are no inspections here.

[Lutrova]

I wanted to avoid the California smog question entirely, which is why the car is titled and registered in Minnesota. It may eventually have to pass Pennsylvania inspection if we end up moving there, but for now I'm dodging that bullet.

It's interesting that a single cat could replace two when I understood aftermarket converters to be much lower in precious metal content. It's also interesting how wide the price range is for them, too. Do the cheaper ones just crap out sooner? Presumably it takes the same amount of catalyst to effect the conversion on a cheap one as on an expensive one.

Are O2 sensors something I should be replacing prophylactically?

[VicCrownVic]

Cat manufacturers recommend changing O2 sensors. This is likely because if you are replacing cats there is likely a reason which could be bad O2 sensors. They don't want to hear it if your new cats go bad because the initial problem wasn't fixed. In your case you probably don't need to buy new O2 sensors. Even though my old sensors were fine I bought new sensors anyway since I was already there and didn't want to fight the old ones out (again, lots of rust in Michigan.)

[gadget73]

yeah, converters rarely go bad on their own, its usually overly fat fuel mix, oil burning, coolant burning, something like that.

[sly]

unless you've got 300K miles on it... then they can be worn out.

[gadget73]

true, but still more likely they died because the worn out motor is huffing oil or dumping some extra un-burned fuel out the exhaust. Chicken and egg problem though.

[Lutrova]

I don't expect to have to replace any of the cats at this point, unless one of them has rusted through underneath the heat shield and is the source of my exhaust leak. I wonder whether the one that was replaced wasn't stolen, considering this car probably spent most of its life in South Tacoma, and maybe the upper cat was hollowed out when the replacement was installed.

It also seems that the part of Pennsylvania we're thinking of moving to only has a visual anti-tamper inspection, so I guess all four cats could be gutted and it wouldn't matter. Not that I plan to do so, but not having to pass a smog test is one less thing to worry about.

What does have me wondering is the pipes that run from the smog pump back to the downpipes. Both are rusting out, but the one that crosses over to the drivers side was split in two and patched with some sort of foam-like connector by the previous owner. I can find the right side pipe (E6AZ5F235A) on Amazon, but the left (E6AZ5F235B) seems to be out everywhere.

[sly]

True enough.

[Mainemantom]

FORD AIR TUBE 1986-91 (LEFT) Replaces OE E6AZ-5F235-B Ebay #22433634375

1986-1991 Ford Air Tube Left and Right Sides - OE E6AZ5F235A and OE E6AZ5F235... Ebay #323613403094

Found this for you. Hope this helps

[Lutrova]

Well, the crossover smug pump pipe may be moot. I made another inspection of the cats today while cleaning rust off, and I had misremembered which upper cat was hollowed out. Turns out the only converter that appears to be intact is the upper passenger side, while the lower passenger, which is the replacement, looks like the Tasmanian Devil went through it. Both driver side cats have been completely hollowed out.

So now I really don't know what happened. Someone was very deliberate on the driver's side, and someone, or maybe the same person, also went through the effort of putting in a new converter on the passenger side. But the bottom line is I seem to be batting 0.250 on cats right now.

Which would explain why the exhaust always smells a little rich.

But I'm amazed that this same setup passed Washington's tailpipe test a year ago. And it did it with a clogged PCV valve and non-functional EGR. It was high on hydrocarbons at idle, but it passed.

It also seems safe to say at this point that the smog pump is contributing nothing.