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328i BMW and catalytic converter?

daughter has a 325i with 180,000 miles, 2001, all maintenance done on time [was my car]. Needs new catalytic converter and dealership wants $2800 to replace. We live in KS, she’s in grad school in NE. Is it worth replacing? Is there a less expensive place to take it to be replaced [we aren’t handy] or can she safely drive it back and forth to school etc. thanks!

An independent shop using an aftermarket catalytic converter will almost certainly be less expensive for both parts and labor.

What has failed regarding the converter? Don’t agree to 2800.00 or have you gotten several estimates at this figure?

If the car is not subject to emissions testing, there is no pressing need to replace it…The car will run fine with an inactive converter…If the converter(s) are plugged up, they can be removed and replaced with a generic after-market part…

My mistake, it is a 325i. When the car is initially turned on white smoke bellows out of the exhaust. The dealership mechanic explained the interior of the catalytic converter was “coming apart”? I have not gotten other estimates. Do I need to go to a shop that specializes in working on BMW’S or ? Should this be repaired with a BMW catalytic converter or a generic after-market part or will a shop remove the catalytic converter? thank you all for your comments.

I don’t know what problems this car has, but I know that the fundamental problem is not the catalytic converter. There is nothing that a catalytic converter can do that creates visible smoke.

Is this white smoke blue-white or just white? White smoke is water vapor. Find out where the water is coming from. Blue-white smoke is burning motor oil. Burning motor oil on a cold start usually means leaking valve stem seals, but there are other ways for the engine to suck in oil. I would check the hose from the PVC valve to the intake manifold to see if it appears to be coated with liquid oil. Does the smoke clear up completely as the car warms up?

If you have been blowing smoke out the exhaust for a while, you may also have a gunked up catalytic converter by now, but as I said, that is not the fundamental problem.

I think I remember seeing this “cat coming apart inside” on this site before. Have you asked this question earlier?

Kansas huh? How about Bill’s American Muffler at 32nd and South Seneca in Wichita? Not that any catalytic converter is cheap, but $2800 is ridiculous. And yes, she can drive the car unless the cat is copmpletely plugged, which is unlikely.

Aren’t all smog control devices supposed to be warrantied for 10 years, or is there a mileage figure that this one is well over?

It was mainly the e-39 that had problems with the cat comming apart. Manolito is spot on, trying to fix white smoke and rattling cat don’t go together. It is odd you were able to speak to the mechanic (this does not happen often at BMW Dealers) and even more odd that things are this confused.

8 yrs 80,000 miles on cats, certainly not “all emission control devices”. I did read of some desire to increase the cat. Federal warranty.

This is my first query to car talk altho’ I listen to the show on NPR. This is so helpful it won’t be my last. We are in Kansas City[she Lincoln Ne] so Wichita is 7 hours from her. Any ideas on KC? It is white smoke and the hoses are being changed now. It just started last week to smoke and only on ignition not once you are driving. I think the seals may also need work but the estimate from the BMW place is high for those. This has been a great car and the “BMW mechanic told my husband he wouldn’t put the $2800 in the car” but what I don’t want to do is buy her another used car when this one has been so solid & safe a car. Good question on warranty I’ll check but I think most warranty goes after 100,000.

The e-46 (your car in BMW speak) is the car that all in its size class are judged against. It has its problems but they drive so nice. I would have to see your car as a 2001 e-46 that is not wort repairing must be suffering from other issues. Do you see what you are saying? a 2001 that is not worth repairing? we have a current post from a person that wants to but a 1973 Chevy.

You are correct. Husband talked to service adviser not mechanic. The service adviser is the one who said he wouldn’t spend the $2800 to replace the catalytic converter.

The car has had few problems and all service to include the 80,000 mile major service. As of today, car’s hoses replaced, no longer smoking. Service advisor also told my husband when the catalytic converter fails completely the car will no longer run.
I don’t want this to happen.

Considering I want this car to last, should I have the catalytic converter removed or should I have an independent shop replace it?
thank you all for your comments.

You probably won’t find anyone who will remove the cat. It’s against federal law.

Surely there are independent muffler shops in Lincoln. Do not go to Midas or Meineke, or your BMW and purse may not live through the experience. “Chain stores” are notorious for finding all sorts of things that HAVE to be fixed before you can drive home.

I really don’t think that you car has an actual issue with the cat converter at this time.
If the car does not have any check engine lights on, then the oxygen sensors are not detecting that the cat converter is working outside of normal parameters.

You only need to worry about the converter when the car actually flips the CEL on, and the codes concern the converter.


Get away from the converter and have a real mechanic (not a “service adviser”) determine what is wrong, if anything, with your car…

Let’s go back to “square one”. White smoke is water vapor. It is not and cannot be caused by the catalytic converter. Many service representatives have no clue what they’re talking about. If they did, they’d be in the shop.

I noticed that she’s in grad school in New England and that the shite smoke only comes out on startup. There is the possibility that this is perfectly normal. It’s been getting cooler up here lately, fall is in the air. That means that water vapor in the morning is normal.

Your engine produces water. Gas ia a hydrocarbon, bunch of hydrogen atoms bonded to carbon atoms. When in contact with the oxygen in the air and heat energy is added, the HC molecule tears itself apart and bonds to the oxygen atoms, making primarily Carbon monoxide, carbon dioxide, and H2O. Yup, H2O as in “water”. Since 1/2 of the gas in hydrogen, and it picks up half its weight again in oxygen (two parts hydrogen, one part oxygen), every 10 gallons of gas you burn produces roughly 7.5 gallons of water.

On cool mornings, when the exhaust is still cool, that water condenses into water vapor. And comes out the tailpipe as a white cloud.

She can and probably should have a pressure leakdown test performed on the cylinders to eliminate coolant as a possible source of the cloud, which would suggest a breech in the headgasket. But if she’s unfamiliar with the characteristics of living in NE as fall approaches, she may find that the white cloud is no problem at all.

I close with the reiteration that this cloud, whatever its source, is not being caused by the cat converter. Catalysts by definition cause change without themselves changing…they add nothing to the exhaust stream.

Thank you for your replies. She is in Nebraska but the weather is changing there and here in KS also. The explanation regarding the smoke color and what causes it was helpful.
The white smoke began about 1 week ago and mainly is on startup of the car. I was mistaken when I said yesterday that the smoke was gone. The smoke is there when you turn the car on disappearing as you begin to drive however the car still doesn’t “sound” right nor feel right to me when I am driving it. [I drove it for 5 yrs and it has been a smooth ride now it feels rough with some vibration].
After having had it worked on she says it is driving worse to her. We have received a recommendation on a local garage that works on imports & have an appointment. All of your comments have been helpful. I agree from all your input it seems clear that it is doubtful the catalytic converter is the problem. Thank you for your suggestions and help.

Apologies for the geography error. Being from new England I see NE and it automatically pops into my head.

The added detail helps. While waiting for the sppointment, I’d suggest keeping an eye on the coolant level. If she is in fact drawing coolant into a cylinder through a headgasket breech, it’ll be important to not allow the coolant to drop and the engine overheat. That coud make a correctable situation much worse if it happens.

Let us know how she makes out with the appointment. We do care.

Bad news. Took car to indep. garage with good reputation. Mechanic said he could not “keep it running” Said Cat. converter shot & there are additional problems with the smoke being both blue and white. Said replacing cc was $2500 + blue and white smoke means it is likely there are additional more serious problems. Looks like we are looking for a used car. Not sure what to do with this one. Blue Book = $5000 but I assume that means if it starts and drives. What to do with it?

We are back to the situation where you are accepting a mechanics viewpoint that the cat. converter will prevent the car from staying running, it will not. If the car won’t stay running how can he say the cat. is bad? Is this cat. simply rattling? is this mechanic specific for BMW?. What is pushing this cars bluebook value down so much, high mileage?

Sorry to hear the bad news. The blue and white smoke comment suggests to me a headgasket. That’d be easily verifiable with a pressure leakdown test of the individual cylinders. And on that car it would be expensive to repair. The clouds probably destroyed the converter.

Passages through the headgaskets include both pathways for coolant and for oil. A breech involving both passages could easily be pulling both into the cylinder(s). A breech like that would also cause the poor operation you commented on. And the residue from the improper fluids being burned in the cylinders and pushed out the exhaust can poison a cat converter’s catalytic coating, its “essence”.

As Oldschool pointed out, a bad headgasket will not totally prevent an engine from running. But it will run poorly. It’ll basically be running one cylinder short.

In summary, the cat converter is not the cause of your problems, but it probably is a victim of them. I suspect the cause of the problems is more serious.