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Had my 2000 NB for about a year and a half now; just recently the CEL came on (I forget what the codes were, scanned them & they were for the cat). I've also got the typical rattling sound, smell, and loss of HP that comes with a dead catalytic converter. I have already had it replaced once, now it's blown again :mad:

I'm not 100% sure if the failure was caused by the engine (it drinks oil like there's no tomorrow) or trauma to the underside of the car (both times I've had the cat fail, shortly beforehand I had the underside of the car get really banged up ... first time I bottomed out in a 6" deep pothole, second time I ran over a tree branch I didn't see in the road until it was too late).

I'm going to put ONE LAST catalytic converter on this car, and if that one goes, so does the car. I don't have the time to screw with it right now, though. A few questions:

1. I've got a damn good mechanic with rock-bottom labor costs - where's the best website to find an affordable catalytic converter for a 2000 New Beetle GLS 2.0l gas engine? I know direct fit is best, and I'm trying to keep the cost SANE and REASONABLE.

2. What other parts should I look into at the same time? Last time I had it replaced (by a different, idiot mechanic) the thing rattled, so are there any mounts / bushings I should also tell my current mechanic to look at? Are there any O2 sensors I should buy at the same time? Anyone want to just point me to a website?

3. Like I said, I don't have the time for my daily driver to be up on a lift right now (just started a new job), so I wanted to know what is the possible harm of running on this thing as is for a while. I've noticed a loss of horsepower since it happened, not dramatic but enough to be noticed. The overheating light hasn't come on (even on the hottest days) so the backpressure doesn't seem to be affecting that - yet. Fuel economy has gone down, but not by much.

4. If there's a serious danger of engine damage, anybody want to post a good picture of the underside of a car like mine and show me exactly WHERE the catalytic converter is so I can hacksaw the pipe upstream of the cat? Not permanently, but just to relieve the backpressure for a week or so and only if I run the risk of engine damage otherwise. I don't live in an area with emissions testing, so the worst it'll do is make the car noisey in a different way (from rattling to loud engine sounds).
 

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Discussion Starter #3
That one only has one O2 port ... doesn't the NB have two O2 ports (one upstream, one downstream)?
 

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Yes, they have 2 O2 sensors. The rear one is at the base of the convertor and the front one is on the pipe in front of the convertor. You have room to splice in the convertor between the upstream O2 sensor and the convertor.
 

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Foxie speaks the truth. I hope you aren't putting the OEM cats on the car. $$$

I went to a local muffler shop, recommended by my local shop (that I 100% trust with my car). Took less than a half an hour and it was $170ish if I remember correctly. I know it was less than $200 for the whole deal, part labor and everything. Also took less than a half an hour with no appointment. It was just an off the shelf replacement, no issues.

Also, I don't know what your mileage is, but there was an extended warranty on the cats put out for the 2.0 AEG for 10 years/120k miles. I was out of the warranty on age (but I was only at 90k) but you might still be able to be covered if you have an OEM cat in there.
 

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I want to say, don't quote me, that the lambda 02 is actually *past* the cat. the cat has just one on it, which is to measure fumes before cat exposure, then the one post-cat checks for the cat's job of cleaning the gasses....
 
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I know I'm the new guy, but I have been a mechainc all my life.

Did you get a factory replacement cat converter?, did you make sure the PCV system is working correctly?, Are you sure your not just over filling the oil?

There are just so many factors to consider when having a cat problem.

If this continues to be a problem put what is called a "TEST" pipe in place of the Cat, but I have to warn you this WILL throw the cel on for a lean fuel mix, how ever the car will run much better.

My guess is your overfilling the oil or the pcv is bad, it draws oil into the intake system and burns it, putting those fumes into the Cat plugs it up...
 

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I recommend you get your own personal code scanner too to make sure the codes you get are vw specific codes.

Try the second link in my signature. :)
 

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Discussion Starter #9 (Edited)
I know I'm the new guy, but I have been a mechainc all my life.

Did you get a factory replacement cat converter?, did you make sure the PCV system is working correctly?, Are you sure your not just over filling the oil?

There are just so many factors to consider when having a cat problem.

If this continues to be a problem put what is called a "TEST" pipe in place of the Cat, but I have to warn you this WILL throw the cel on for a lean fuel mix, how ever the car will run much better.

My guess is your overfilling the oil or the pcv is bad, it draws oil into the intake system and burns it, putting those fumes into the Cat plugs it up...
1. Oil isn't overfilled
2. The CAT I had put on last time was an OEM / direct fit.
3. I don't know if the PCV has been checked (I never did)
4. Anyone got a diagram of where the thing is located?
5. What do you have to do to replace it? Pictures are always nice, much better than hand-drawn diagrams :) The most involved I get in my cars is replacing easily-reachable hoses & belts ... something I could feasibly do?

I've had to replace the hoses for the crank case vent system in my 1971 Beetle, which is simple since it's an upright engine and everything except the physical cylinders / pistons / valves is all right up in your face when you open the back end. If you guys think this is something relatively simple (and like I said, can find a picture somewhere of a 2.0l engine indicating where the little bugger is), I'll stop at Autozone on the way home & do it tonight. Then I'll just have the cat to replace.

Hell, I may buy the cat on the way home too, and just let my mechanic splice it in later.
 
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Well sounds like you got a good bead on it. The oil cap, right under it is about a 1 1/4 inch hose that goes into another larger hose (air intake hose). In-between the hose that comes from the oil cap area and the air intake hose is a two wire sensor, that my friend is your PCV valve.
 

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Discussion Starter #11
Well sounds like you got a good bead on it. The oil cap, right under it is about a 1 1/4 inch hose that goes into another larger hose (air intake hose). In-between the hose that comes from the oil cap area and the air intake hose is a two wire sensor, that my friend is your PCV valve.
Cool. I wish I could find a picture of the little bugger - I've been Googling around most of the morning and have seen a couple different looking ones. I'm not in front of the car now (duh) so I'll have to get a detailed look later ... do I need to remove the cowl over the engine (or anything else) to get at this guy?

Also, should I fuss with replacing the hoses at the same time if they look ok, or just rock 'em for now?
 
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Cool. I wish I could find a picture of the little bugger - I've been Googling around most of the morning and have seen a couple different looking ones. I'm not in front of the car now (duh) so I'll have to get a detailed look later ... do I need to remove the cowl over the engine (or anything else) to get at this guy?

Also, should I fuss with replacing the hoses at the same time if they look ok, or just rock 'em for now?
Let me go snap one for ya right now.
 

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What kind of mileage do you have on it that you're not having the cat replaced under warranty by the dealer? Or is it 10 years? They just told me when I took mine in that if it was the cat (it wasn't of course) that VW extended the warranty and it would be covered. I have an 01 GLS 5 spd but it wasn't put into service until October of 2002....that's the date they go by apparently. Hope it works out for you. These cars can be tricky.
 

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Discussion Starter #15
You are the awesome :) I'm having trouble finding one online at Advance Auto Parts / Autozone (the closest places to where I am).

How would a "bad" one of these cause oil consumption - too much pressure in the crankcase like on my '71? If I can't find one of these at the Autozone, can I just shove a straight pipe between the two hoses until one gets here in the mail from an online retailer?
 
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You are the awesome :) I'm having trouble finding one online at Advance Auto Parts / Autozone (the closest places to where I am).

How would a "bad" one of these cause oil consumption - too much pressure in the crankcase like on my '71? If I can't find one of these at the Autozone, can I just shove a straight pipe between the two hoses until one gets here in the mail from an online retailer?
PCV = positive crankcase ventilation valve. What it does is open for a small peiod of time allowing burnt oil FUMES to escape thru the intake manifold and then closes. Now when the valve is stuck open it continually suck's, thereby sucking the oil out of the crankcase causing a continual low oil condition and plugging the cat, because cat's are for removal of harmful enviromental gasses, not to burn off oil. So it plugs up.

As far as a straight hose, I dont think I would do that, you might make it worse.
 

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Discussion Starter #17
PCV = positive crankcase ventilation valve. What it does is open for a small peiod of time allowing burnt oil FUMES to escape thru the intake manifold and then closes. Now when the valve is stuck open it continually suck's, thereby sucking the oil out of the crankcase causing a continual low oil condition and plugging the cat, because cat's are for removal of harmful enviromental gasses, not to burn off oil. So it plugs up.

As far as a straight hose, I dont think I would do that, you might make it worse.
Ok, now I'm understanding it. I was thinking in terms of my 1971, where the idea is the same (burn fumes from the crankcase and also pull some negative pressure to relieve pressure in the case), but execution is different. Since the hose goes UP from the filler tube and then sideways to the air cleaner (the air cleaner itself in a stock model, being filled with oil to clean the air almost like a bong for your car, rather than a paper element) there was no valve to prevent oil "backwash" - it was nearly impossible to have that, and if it did happen, the worst you'd get is blue smoke, if anything at all.

If I can't get the valve tonight, would there be any harm in plugging those two ends of hose where the valve comes out, temporarily while I wait for delivery, and see if this alleviates (or at least reduces) my oil consumption?
 

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Are you out of the extended warranty on the cat? If you are under 120k miles you should be able to get a replacement for free from VW. Or at least reimbursed for the first replacement (not sure how it works for subsequent OEM cats).
 

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Discussion Starter #19
Or, another thought, what about just removing the hoses and putting little breather filters in there and forgetting the valve / letting the crankcase vent to the outside air? One filter on the crankcase breather outlet to keep gunk from getting in there, and one at the input on the intake manifold to prevent gunk getting in that end?

This is how my 1971 Beetle came to me when I bought it last year (one small filter on the crankcase breather, and the inlet on the air cleaner above the carburetor capped / plugged).

Is the purpose of the PCV only environmental, or is like in the 1971 where it actually alleviates pressure in the crankcase? If the entire thing is just environmental, then screw it as far as I'm concerned - I don't live in an area that gets emissions testing. Having the valve removed & a filter in its place should let the engine alleviate all the pressure it wants ... I'd still have to keep an eye on oil levels, but at least they'd be blowing into a screen and not into my freaking intake / CAT.

 

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Discussion Starter #20
Are you out of the extended warranty on the cat? If you are under 120k miles you should be able to get a replacement for free from VW. Or at least reimbursed for the first replacement (not sure how it works for subsequent OEM cats).
Fighting warranties is a pain in the ass, especially if I already know that the issue isn't the fact that the cat failed, it's something on the car caused it to fail. The cat didn't suffer from bad workmanship; the fact that this car has had AT LEAST three cats on it in its lifetime (and needs a fourth) means something else is causing it.

Considering the amount of oil I'm losing, we may be onto something with the PCV. At least it's a cheap "try it & see, no harm either way" test fix.
 
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