[andrewSF]

Can anyone recommend a shop in bay area to weld in a catalytic converter, in SF bay area? Anyone have recent pricing on shop charge to do this?

I have 1999 E320 with around 72k miles. I just heard a rattling noise around the catalytic converters' location. I will do some more checking and may bring it in to indy shop for an opinion, but a bad/ failing cat seems to be consistent with the fuel trim data that I have been seeing on this car for the last couple of years. I think I had even started a thread a while back about poor gas mileage, and couldn't understand the elevated fuel trim as a function of intake air temp. Now, it seems to make some sense if the cat was getting more clogged during a drive cycle, particularly during city driving. Freeway driving during the drive cycle would slowly bring down the positive fuel trim--an indication that the higher engine RPM was able to force the exhaust through the clogging cat?

Anyway, I may add some more diagnostic info to this thread as I try to pinpoint/confirm bad cat. I have never had a check engine light come on, in this car. I did have a pending error code on bank 2 pre-cat O2 sensors recently and have changed that sensor. I am not sure if that issue was related to a failing cat. The pending errors were for an O2 sensor heater circuit problem and narrow voltage range on output signal.

Based on G-AMG's sticky thread, I am planning to get MagnaFlow catlytic converter(s) as replacement. These parts are now available on amazon @ around $145 to $160 each, from different sellers. For my California vehilcle, it appears that MagnaFlow 441304 and MagnaFlow 444104 are the correct cats for rears and fronts, respectively.

 

[emeshuris]

literally any decent muffler shop will do. what does the magnaflow item run?

 

[andrewSF]

MagnaFlow 441304 is currently $149 @ amazon through "Amazing Prime" seller. MagnaFlow 444104 is $162. Other sellers have different prices. Non-California compliant MagnaFlow cats are cheaper.

 

[emeshuris]

thats pretty reasonable, are they more performant compared to stock?

 

[tabijan]

Outfits like Pelican Parts and FCP Euro have bolt on catalytic converter sections (both cats) for ~$270 each with $200 core charge. You can probably change a section in an hour on a clean Bay Area car. I don't know if that's more cost effective than muffler shop fees after shipping the core.

If you have new cats welded on, make sure the CARB tags are plainly visible. I failed a smog check earlier this year because the PO didn't have documentation to pass to me for the aftermarket cats, and the tags weren't visible as installed. Instead I got a cat section from a fellow parting a similar car. Plan B was to risk returning the cat section with aftermarket cats as a core. Pelican Parts said they couldn't confirm that it would be an acceptable core until MB inspected it. MB has to approve the core :/

Sixto
98 E320s sedan and wagon

 

[andrewSF]

thats pretty reasonable, are they more performant compared to stock?

I don't know. According to G-AMG in his thread, they felt about the same as stock with a slightly throatier sound--if I remember what he wrote correctly. I believe he put in only the rear cats on both sides.

 

[andrewSF]

Outfits like Pelican Parts and FCP Euro have bolt on catalytic converter sections (both cats) for ~$270 each with $200 core charge. You can probably change a section in an hour on a clean Bay Area car. I don't know if that's more cost effective than muffler shop fees after shipping the core.

If you have new cats welded on, make sure the CARB tags are plainly visible. I failed a smog check earlier this year because the PO didn't have documentation to pass to me for the aftermarket cats, and the tags weren't visible as installed. Instead I got a cat section from a fellow parting a similar car. Plan B was to risk returning the cat section with aftermarket cats as a core. Pelican Parts said they couldn't confirm that it would be an acceptable core until MB inspected it. MB has to approve the core :/

Sixto
98 E320s sedan and wagon

Thanks for bringing up the other online outlets, and the warning about the CARB tags.

I had forgotten about Pelican Parts and FCP Euro. FCP Euro is especially interesting since they apparently have an unlimited lifetime warranty. Never did business with them, but had watched a few of their yourtube videos before.

I still need to do some more diagnostics, but I think my front cats are OK, but the rear cats on both sides are bad. The rattling sounds like it's coming from the middle of the bottom of the car--where the rear cats are. I don't hear the rattling from under the hood. My general impression is that most of the posts in this forum about bad cats are regarding the rear cats.

I took heat gun measurement and found that the temp at the input of both rear cats was about 300 deg F and the output was about 225 deg F. I believe this indicates cat failure. I didn't do the measurements for the front cats yet. However, the post cat O2 sensor sits between the front and rear cat, and the output voltage of this sensor is around a steady 0.7V (both banks) for the most part, and I believe that this indicates that the front cats are functioning OK. The car had just passed California emissions testing a month or so ago. Frankly, I don't know what is the emissions function of the rear cats. They perform "backup" cleaning, while adding the risks of restricting exhaust if they fail?

The intake manifold vacuum seems to snap back pretty quick from a wide open throttle snap. And the manifold pressure holds steady at around 8 in Hg when engine is held to around 2500 RPM, compared to around 13 in Hg at idle. I believe that both of this two tests indicate that there is not significant back pressure going back to the intake, as a result of the clogged cats. These data points appear to be consistent with the front cats not displaying much exhaust restriction. All my interpretations are based on my understanding from recent research on the Internet, so please chime in if anyone has corrections or comments on this.

I'll be putting the car on jack stands so I can look for any loose metal contact that could cause the rattling. At this point, I am more inclined to think that the rear cats are bad or starting to fail. This is also supported by my observation that the LTFT on both banks steadily increases with prolonged city driving but will gradually decline with an extended freeway drive--with my hypothesis being that the rear cats gradually becomes clogged and more restrictive during city driving but are somewhat "cleared" out by the more powerful exhaust at freeway speed. I've observed this the last couple of years on my car but never understood it. Failing rear cats seem to explain it--if my novice understanding of everything is correct.

 

[emeshuris]

@andrewSF man thats alot of diagnostic info. off the top of my head your numbers seem right. my buddy taught me a trick to silence cats, stick a chopstick or two throw the shell and into the assembly inside. ?i havent tried, but no doubt it would work, hes an old school pink slip racer.

im in california and am about to get my g smogged, looking at the star system and even my cheapie odb reader, both have tests for cats, and if those tests fail, smog check will fail also. did you have the rattling before/during the test?

 

[fosmith]

I had a Magnaflow rear cat welded in at Exhaust Specialist-Burlingame The guy's name was Louis and he did a great job. It cost about $75, IIRC. BTW, it's usually the rear cats that cause the rattling. You can identify which one is rattling by hitting it with a rubber mallet or the soft side of your fist (after it's cooled off, of course).

Fred

 

[andrewSF]

@andrewSF man thats alot of diagnostic info. off the top of my head your numbers seem right. my buddy taught me a trick to silence cats, stick a chopstick or two throw the shell and into the assembly inside. ?i havent tried, but no doubt it would work, hes an old school pink slip racer.

im in california and am about to get my g smogged, looking at the star system and even my cheapie odb reader, both have tests for cats, and if those tests fail, smog check will fail also. did you have the rattling before/during the test?

I heard the rattling for the first time on Sunday. But I always drive with the windows closed, so I don't know when it started--I don't hear it inside the cabin. I only heard it because I opened the driver door slightly as I was pulling into a parking space to check the car's alignment in the space. Apparently, the rattling only starts after the car has warmed up. I had changed the oil couple of weeks ago and was standing outside the car with the car idling for 5 to 10 mins and didn't hear anything.

I had smog check on 7/12/17. I would think the shop would have said something if the car had a rattle then. But I don't know. The test results look very good, to me.

Actually, I would like to just cut out the rear cats and throw them into the Pacific Ocean. If they're not important enough to have their output monitored by the post cat O2 sensors, then I don't know why they're there.

 

[andrewSF]

I had a Magnaflow rear cat welded in at Exhaust Specialist-Burlingame The guy's name was Louis and he did a great job. It cost about $75, IIRC. BTW, it's usually the rear cats that cause the rattling. You can identify which one is rattling by hitting it with a rubber mallet or the soft side of your fist (after it's cooled off, of course).

Fred

I had just called that shop yesterday! I found it from an Internet search, and the online reviews seem good. I had dealt with a few indy shops in Burlingame, and feel comfortable with shops there. If it is a one person shop, then I spoke with Louis on the phone. He sounded very reasonable. I'm not going to look any further for a muffler shop.

I believe my temperature test is conclusive and that both rear cats are bad because they are not heating up the exhaust gas as they should. But I will try the rubber mallet test you mention--thanks, Fred. Ideally, I think I should do a back pressure test by pulling out the pre and post cat O2 sensor and testing the pressure there. "The Internet" says it should be virtually 0 psi @ idle and up to 2 psi on ~2500 RPM. I'm expecting some exhaust back pressure before the rear cats, but would be interested to seeing how much back pressure is pushed back through the front cats, assuming the front cats are good and not contributing to any back pressure.

 

[emeshuris]

Actually, I would like to just cut out the rear cats and throw them into the Pacific Ocean. If they're not important enough to have their output monitored by the post cat O2 sensors, then I don't know why they're there.

lets not throw them into the ocean, but how do you figure they are not being monitored?

 

[andrewSF]

lets not throw them into the ocean, but how do you figure they are not being monitored?

Because I can see the "post cat" O2 sensors on the exhaust pipe, between the front and rear cats (on each bank). The pre-cat O2 sensors are in the engine bay, right before the front cats. The pre-cat O2 sensors are called "O2 sensor 1", for each bank, in your OBDII scanner's live data feed. The post cat O2 sensors are called "O2 sensor 2". The function of the pre-cat O2 sensor is to monitor the amount of oxygen remaining after engine combustion so the ECU can adjust fuel trim appropriately, for emissions control. The post cat O2 sensors are for monitoring the efficiency of the catalytic converters. It monitors for the amount of oxygen remaining (I believe) in the exhaust after the catalytic converter, to make sure the catalytic converter is doing its job.

If the post cat O2 sensor is placed BEFORE the rear cat, that means the car isn't even looking at the output of the rear cat, and therefore is not monitoring its operation. If the Mercedes engineers had placed the post cat O2 sensor AFTER the rear cat, then the car would be monitoring the emissions effect of BOTH front and rear cats.

 

[tabijan]

Yet the darn smog check needs rear replacements to be CARB certified like the fronts. Sheesh!

Sixto
98 E320s sedan and wagon

 

[Shawndh]

Can anyone recommend a shop in bay area to weld in a catalytic converter, in SF bay area? Anyone have recent pricing on shop charge to do this?

I have 1999 E320 with around 72k miles. I just heard a rattling noise around the catalytic converters' location. I will do some more checking and may bring it in to indy shop for an opinion, but a bad/ failing cat seems to be consistent with the fuel trim data that I have been seeing on this car for the last couple of years. I think I had even started a thread a while back about poor gas mileage, and couldn't understand the elevated fuel trim as a function of intake air temp. Now, it seems to make some sense if the cat was getting more clogged during a drive cycle, particularly during city driving. Freeway driving during the drive cycle would slowly bring down the positive fuel trim--an indication that the higher engine RPM was able to force the exhaust through the clogging cat?

Anyway, I may add some more diagnostic info to this thread as I try to pinpoint/confirm bad cat. I have never had a check engine light come on, in this car. I did have a pending error code on bank 2 pre-cat O2 sensors recently and have changed that sensor. I am not sure if that issue was related to a failing cat. The pending errors were for an O2 sensor heater circuit problem and narrow voltage range on output signal.

Based on G-AMG's sticky thread, I am planning to get MagnaFlow catlytic converter(s) as replacement. These parts are now available on amazon @ around $145 to $160 each, from different sellers. For my California vehilcle, it appears that MagnaFlow 441304 and MagnaFlow 444104 are the correct cats for rears and fronts, respectively.

I called the local dealer and they had reman units for around $280-$300 when you bring in your old core. It was really easy to unbolt and install the new unit. It has 2 cats on it. Hardest part was getting the car in the air. No welding needed. I too did not have a CEL but fuel trims were off and a sputtering sometimes at low idle.
Basically, if you can wrench, you may come out better checking with the dealer.

 

[andrewSF]

I called the local dealer and they had reman units for around $280-$300 when you bring in your old core. It was really easy to unbolt and install the new unit. It has 2 cats on it. Hardest part was getting the car in the air. No welding needed. I too did not have a CEL but fuel trims were off and a sputtering sometimes at low idle.
Basically, if you can wrench, you may come out better checking with the dealer.

I called Autobahn Motors in Belmont. Woman on phone gave me price of around $410 for each side. However, she said it was ONLY for the front cat. Started to question her about it, but couldn't get more information before call had to be terminated because of bad connection. I'll follow up later.

Replacing the entire pipe with both catalytic converters intact does sound attractive. Will definitely consider this--whether buying from dealer or from FCP Euro. Need to price out shipping charge for CORE return if buying online, etc. Will also ask muffler shop for opinion. I'm thinking the front cats may not fail in future, so welding in just rear cats may be an OK solution--and the aftermarket cats may even be better than the Mercedes one. However, if front cats fail afterwards, it looks like they will probably need to drop the entire exhaust pipe to cut and weld in new front cats and I would be wishing that I had changed both when I had a chance. All this assume that my front cats are OK. If they're not, the OEM replacement exhaust segment is the obvious choice.

But I still need to do some more homework on confirming the bad cats, etc. I did find that, when doing the temp gun test, you need to be careful about pointing the temp gun. If you point at the ends of the actual converters, you will get a lower temp than if you point at the exhaust pipe before/after the converters. I guess this is because of the insulation of the canisters.

FYI--for this thread, I just stumbled on this youtube video that shows a 2003 E55 with rear cats removed. The link below should start at the point in the video that mentions it. [EDIT: the catalytic converter part starts at 6:54 in the video.] Thought it may be interesting for some to see: [ame]https://youtu.be/LuklsA__9Gk?t=6m54s[/ame]

 

[tech4tech]

This guy is very good(also in belmont)
https://www.yelp.com/biz/exhaust-works-belmont