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YOUR RESEARCHCatalytic Converters
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Replace wrong cat
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Leading evidence: 'Replace wrong cat' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'larger issue' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check these parts' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Use autohausaz as they were cheaper than warehouse33
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Performed · outcome unconfirmed
Those part numbers were super helpful--I ended up using autohausAZ as they were cheaper than Warehouse33 after shipping.
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Performed · outcome unconfirmed · Original poster
Its why I bought a cheap pair of used cats, we'll see how long it lasts.
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Performed · outcome unconfirmed
Also I just used good quality 8.8 grade M8 x 35 bolts for the manifold to catalytic converter - I'd use genuine bolts for the manifold to block though.
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I use PB B'laster (or PB Blaster) whenever I need to remove O2 sensors (or anything corroded).
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Suggestion · Original poster
Maybe its possible I disconnect the the downpipe and move it around to get a better angle, but the wife was nice enough to run to HD while I'm working today.
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Suggestion
Remember to turn the crowsfoot on a 90 degree angle and don't ratchet it from that position - also do not put it on the wrench inline as your torque spec will be off (force will be increased from what you've set).
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Rennlist: 1 discussions
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Had never tried that trick before, but it worked quite well and was a lifesaver.
The driver's side is rattling. I've seen OEM for ~$1600 after $800 core charge. I'm in CA, what are my options?
My indy tells me the OEM will last longer than the aftermarket. Given the cost of this part, it's going to be DIY. I imagine it's pretty straight forward. Do I just replace both or wait until the other craps out? Any issues with running one stock and one aftermarket?
Thanks in advance.
You may want to search for "porsche 996 down pipe" on ebay and find a good used one for your model. Best are listings that include the info of the scrapped car with mileage.
What yr is your 996? Usually lots of listings for the 3.4
LOL.....just learned that "down pipe" is code for "Cat that can't be legally sold as a cat".....thanks for the education!
I would definitely go with a used OEM unit.
It's 3.6L. My indy told me that brick depletion is a function of mileage not age. My car only has 36K on it. Is that normal?
Ahsai, are your Carnewal cats still holding up?
I PM'd you strathconaman, I'm definitely interested.
At 36K something killed it off.
I'd worry about leaking fuel injectors on the opposite side or something causing a rich condition.
Fix that before replacing the Cat.
My 996 has 64K and still has the stock Cats...and THAT is low mileage.
I'll sell you mine and get 200cel Fabspeed cats for myself.
Yes, my 200 cell sport cats from Carnewal are still holding up well. The cats for 3.6 come up from time to time on ebay.
Yes, the element basically dislodge from the can and that can happen at any mileage.
I've looked into this as I'm also in need of a driver's side cat for 3.6. Aren't the 3.4 and the 3.6 cats interchangeable? Planning on getting a used OEM for the time being, but going catless eventually. And for reference, mine went at 49k.
I put the Topgear 200 cell cats on my 2004 AE. They have been great with no codes thrown. My wife even commented on how much better the car sounds then a newer 997 sounded when it went by. Surprised by that.
And a pair of them are less than $600 shipped.
In CA, we cannot use any aftermarket cat unless it's carb certified. Certified cats will have a carb number stamped onto the housing. It's part of what they look for during visual inspection. Magnaflow is located in CA, so they're probably the only company (for our vehicle) that offers replacement cats and understand the CARB requirements. Every other company will just sell you something that's "for off road use only"...
I don't know enough about the matter to answer that definitively if we're comparing apples to apples. Magnaflow doesn't list cell count or any details other than its carb compliant.
https://www.magnaflow.com/products?partNumber=444066
My service manual says I can remove the O2 sensors with a 22 mm open ended wrench or special tool 4681-3. It would be nice to use my torque wrench when putting the sensor back in, but the specified 40lbs is just about snug tight. Any reason I should fork out the $100 for the tool (or borrow from autozone if available)?
I have some sort of low cost offset O2 sensor socket that I got years ago from a local auto parts store that goes on a ratchet wrench. It works great, and has a slot for the wires. I've used it on many cars. Well worth the couple of bucks it cost.
Something like this:
Amazon
Amazon
Just get a 22mm crowsfoot and a short extension and you can then use your torque wrench.
Remember to turn the crowsfoot on a 90 degree angle and don't ratchet it from that position - also do not put it on the wrench inline as your torque spec will be off (force will be increased from what you've set).
I think I picked mine like that one up at Autozone years ago.
I use it, the one at the bottom, or a 22mm (7/8") open end wrench.
One or the other usually works on just about any car.
If you're pulling the downpipe/exhaust manifold on most cars, the socket above, or one like the one below works great.
Amazon
Amazon
+1 This can also be used with a torque wrench (with the socket and the torque wrench forming a 90 degree "L").
Also, probably obvious but install the sensors before you put the new cats on the car. If reusing old sensors, make sure you apply anti-seize on the threads of the sensors.
Note you won't be able to use this one in the amazon link due to limited space around the 3.6 O2 sensors (if you need to remove the sensors when the cats are still on the car).
Yeah, sorry, I meant it is good for when the exhaust manifold/downpipe/cat is off the car.
Sometimes it will fit while they're still on some cars, but not all the time.
The crowsfoot one almost always fits when they're still on the car.
On customer cars I usually give it a try without any penetrating oil first.
I rarely need to use any.
Of course I live way down south in a non-rust area.
I’m currently working on a 2003 Buick from OH, and it is super rusty!
I imaging the O2 sensors would be a pain to remove like everything else on this car.
I use PB B'laster (or PB Blaster) whenever I need to remove O2 sensors (or anything corroded).
It is an excellent penetrating catalyst. My understanding is that it does more than lubricates, that it actually breaks down the corrosion. I do not understand the science, only that it works better than any other penetrating fluid I've tried.
Sometimes it requires multiple applications over the course of several days for really rusted on stuff. For those projects, I try to plan ahead.
It is also nasty, stinky, messy stuff, and burns like hell if you ever get it in your eyes.
http://blastercorp.com/PB-Blaster-Pe...ck-parts-spray
A couple of applications of PB Blaster was enough for me, but I removed the CATs prior to trying to remove the O2 sensors. Careful of the 02 sensors...apparently they can be fouled quite easily.
The crowsfoot is requisite for the driver's side post catalyst sensor on mine. Maybe its possible I disconnect the the downpipe and move it around to get a better angle, but the wife was nice enough to run to HD while I'm working today.
Can anyone recommend a good source for new gaskets/hardware to install along with a new catalytic converter? I'm about to replace mine and figured it would be best to replace the hardware at the same time. I'd rather not shell out $157, which is what FVD wants:
https://www.fvd.net/us-en/FVDMK99630...onverters.html
Check with Warehouse33.
They can get you all the hardware cheaper.
Just $105 unless you want Genuine Porsche clamp, then it is $162.
(Use the coupon code RENNLIST for an additional 10% off)
Gaskets
https://www.warehouse33auto.com/cata...anifold.Gasket
Clamps
https://www.warehouse33auto.com/cata...-Exhaust.Clamp
Bolts
https://www.warehouse33auto.com/cata....Manifold.Bolt
Nuts
https://www.warehouse33auto.com/cata...st-Exhaust.Nut
You might also check for these parts on Pelican and Suncoast/Sunset RockAuto websites:
I know it might be a little late, but I was able to get high quality, full stainless steel M8x40mm, locking washers and nuts for less than $10 at the local hardware store.
I just getting around to working on this. 2 questions:
1. Can I reuse the gasket?
2. The used down pipe I got needs to have the bolts replaced. Is there a trick to getting these bolts off other penetrating oil? I don't really want to tap it out for fear of dislodging the catalyst element.
Thanks in advance.
I would highly recommend using new gaskets and make sure all the mating surfaces to the gasket are clean and smooth. The reason is if you have any leak here, it would give you CEL issues.
You can try kroil on the bolts but if they are too rusted, you may need to cut them off.
my 3,4 had 140,000 miles with the original cats and passed California emissions without any problems this pas year so I would just offer that as a comparison. I am very handy and I was always reinforced by auto mechanics that a cat SHOULD last the life of the car unless it was physically damaged or the engine had a problem with air/fuel or temperature. Because the cats hang so low on the tail, it�s conceivable that it was damaged by a hit or drag on the road.
I tried using my multitool to saw it off, I just don't have the level of control that I need to saw it off without damaging the surface that lines up with the exhaust manifold. I'm going to get some cobalt drill bits today and tried to drill it out.
You could try a dremel with a reinforced cut off wheel - would give you more control
Also I just used good quality 8.8 grade M8 x 35 bolts for the manifold to catalytic converter - I'd use genuine bolts for the manifold to block though.
Thanks Dan. I'm going to take them in to a local muffler shop tomorrow. I've been messing around with these too long. In case any gets and ideas, you'll be drilling for days with a hand held drill and cobalt bits. Also forget about the Fein oscillating Multitool. The Dremel might work, but I'm done. Time to hand it off to the pros.
Well, I've replaced the wrong cat. The mechanic said driver side cat and I didn't bother to verify. Good thing I got a pair.
I had to remove both cats to swap out the drivers side. So the passenger side also got a new gasket. I assume I still have to replace that brand new gasket?
By the way, if anyone gets downpipes with broken bolts, they can be pressed out after applying some heat. I don't have equipment to do either, the local machine shop did it for $40.
Cool, I reused the "new" gasket. No issues on the brief shake down run. We'll see how this cat holds up. If it goes bad soon, I'll know there's probably a larger issue that needs to be addressed.
Well, I finally got a decent drive in. I was saddened to notice a lot of previous growly exhaust note was in fact, a bad cat. She runs silky smooth now, but too smooth and quiet for my tastes. Will be looking at alternatives...
For the next person: You probably don�t need heat, I was able to remove the pressed in studs on both of my cars with a 3lb hand sledgehammer and bench vise.
Same experience here, except no vise. Just some penetrating oil and a few whacks with the sledgehammer and the old bolts pop right out. I also had to use the sledgehammer in conjunction with a chisel to remove a stuck/stripped nut when removing the bad cat. Had never tried that trick before, but it worked quite well and was a lifesaver.
This is a source reference. Confirm exact model applicability in the original material.
