'96 LHS cats

I have a 96 Chrys LHS. Its catalytic converters are 3, one for each exhaust manifold/bank and one central behind those.

The rear/central has been replaced with an aftermarket replacement about a year and a half ago. The two front ones are 'weird' in their configuration and there isn't any aftermarket version available in the sources I've checked. Currently the information obtained from a dealer by a mechanic friend of mine indicated that -1- the dealer didn't have any/either in stock and he would have to 'dig them up' somewhere if necessary and -2- the cost of the two totaled about $1300 retail, with one of them priced almost $200 more than the other. They look about the same to simple inspection.

If I should come to need one or both of those cats, how does the common man solve such a problem?

I've heard that once upon a time there was such a thing as removing a cat and having it rebuilt with certified cat biscuits/interiors. What is the story on that?

Reply to
Mike Easter
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I would have thought that the third unit that you speak of is just a combiner and not another cat unit, but I see that indeed the combiner (that takes the left and right-side exhaust manifolds and combines them into a single pipe that runs to the back of the car) is acually also a cat converter.

I have no idea why that combiner unit also needs to be a cat convertor. My '00 300m (with the same engine as your '96 LHS) does not have a cat converter in that position. Oh well.

Last year I had to replace that combiner unit (with an aftermarkt stainless steel unit) and one of the flexible couplings on the driver's side manifold pipes (this on a '00 300m). The combiner unit (in my case) is really just another muffler (2-inputs, one output).

I've been told that the catalytic convertor units (left and right) are very expensive. Are you sure that your's is defective? It's relatively common for the flexible joints to go bad, and (as in my case) it is possible to replace them without touching the convertors.

How about this:

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I'm surprised that these are mostly listed for under $200 each.

I would think that as long as you can obtain one cat (or two, if you need both) and not necessarily a unit that is specific to either Chrysler or to the LHS, that if you find a competent custom exhaust shop that they can fabricate the pipes and weld the cat units into place.

I'm pretty sure that you probably have stainless steel pipes and components (at least originally from the factory) but given the car's age, you probably don't expect to keep the car for more than another 5 years, so replacing any pipes with stainless steel (instead of aluminized steel) is probably not useful from a cost/benefit POV.

Even if you obtain any of these parts yourself, you should have no problems handing them over to your exhaust shop for installation. Although, if you're located in California, things might get tricky for you.

As I've not yet ever had to deal with a cat replacement, I've never heard of such a thing, but others here might have.

My gut feeling is that as long as your exhaust shop can obtain a generic cat (with the correctly inlet and outlet pipe-opening size) that you should be able to weld the replacement cat's into place with a minimal amount of modification / replacement of the existing pipes and (especially) the front coupler.

If the coupler is still good, you don't want to mess with it because you'll be looking at an extra $100 just to replace it if it can't be taken apart without dammaging it.

Reply to
MoPar Man

Thanks for your input.

It passed CA smog check 1 year ago. Recently the check engine light came on which 'suggested' the R cat's function. A friend with some experience had a computer that allowed us/him (I was confused by the dynamic readout) to look at the upstream and downstream O2 levels comparing one side to the other. If people like to think of cats as getting 'tired', I suppose that was the idea he was trying to get across. He turned off the check engine light and I'm waiting to see if it comes back on now.

Good point.

The sources an exhaust welder friend checked for me were for parts about CA aftermarket jobs he does.

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A wonderful term '49 state' (everywhere but CA) appeared in two of those links.

I understand the 'tricky' concept.

Thanks again. I just got my CA registration renewal for this car and it doesn't require smogcheck this year, so I'm good for at least June 2010 minimum.

Reply to
Mike Easter

If you're not to far away, come to visit a neighboring state, (NV, AZ, OR), rent a box at one of the shipping & mailboxes stores (eg UPS Store), go home and order a CC and have it shipped to the box. If they won't ship via credit card to a non-home address, use mail order and pay with a money order. Track the shipment online, once it's delivered, go back and pick up the CC, and close the box. Install. Problem solved. $$$ saved.

Reply to
Zaphod Beeblebrox

Indeed. I grew up in TX, I have family there, and in fact the car was originally a family member's TX car.

So, I could 'work it out' with getting parts to TX and thence to CA and solve that 'tricky' part. The tricky part about the installation I'll ask a few questions next week to see what those guys are comfortable with.

Reply to
Mike Easter

... but all of that is a far-fetched plan B for the future if 2010 Jun has me with the car and a smog problem.

Plan A is currently doing nothing and wondering if that check engine light alert is even going to come back on.

I'm thinking that if the same engine didn't even have a 3rd cat, with my brand new rear cat taking care of a little weakness in one of the front cats, I'll probably be OK anyway.

Reply to
Mike Easter

You sure about that - they're both 3.5L, but I don't think they're the same design. I could be wrong.

Reply to
Bill Putney

Even if they're different, why should the '96 3.5L require a third cat in addition to the left and right side cat's ?

Also, are there any sensors in the exhaust stream? If so, where? Before, or after, the cats ?

Reply to
MoPar Man

There are sensors before and after both L & R cats. Then later comes the middle/rear cat.

The before L&R cat sensors are best seen/found from the engine compartment not far past the manifolds, the after L&R cats from underneath not far forward of the mid/rear cat.

I had occasion to see all of those sensor connxns Friday.

Reply to
Mike Easter

Its much more probable that what is getting "tired" is either the upstream or downstream O2 sensor that is then giving false erroneous readings to the engine management system. Either that or another engine management problem like a leaky injector causing an excessively low O2 reading on one bank but not the other, or an intake leak causing a high O2 reading on one bank but not the other. Those upstream cats very rarely fail on LH cars, unless there's a catastrophic problem like a badly leaking fuel injector or an un-treated misfire that causes a severe overheat.

Reply to
Steve

Not if the front cats are reduction catalysts and the rear cat is the oxidation catalyst.... if so then all 3 need to work. I'm not sure how the 96 LH is set up in that regard.

But you're still HEAVILY speculating. Cats rarely fail, CELs are almost always set by some other problem throwing the O2 readings out of balance.

Reply to
Steve

Ah, so. Perhaps it needs more accurate diagnostics than he was using. Those O2 levels upstream and downstream were all over the map on both sides to my untrained eye.

Reply to
Mike Easter

This is 3 days later and I'm still waiting for the light to come back on.

Reply to
Mike Easter

Mike,

If it does, make sure it isn't just the O2 sensor... A much simpler and cheaper fix.

Bob

Reply to
Bob Shuman

Reply to
Phillip Mcracken

If you do replace O2 sensors, do *not* use Bosch sensors - they do not work on the LH cars.

Reply to
Bill Putney

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