Good sources for cats?
 

The shop tells me that my 400e needs a new cat. They want about $1400 for one, FastLane wants about $800

Any additional recommendations?

Is one any better than another?

TIA

IIRC Neil/ke6dcj said Catco cats work well as replacements but you have to add flanges since they don't make MB specific cats.

Did you try www.timevalve.com?

Sixto
95 S420
87 300SDL

I got one from here. Though they said it was 'direct fit' it took a little work to make it fit with no leaks.

Heck, if there's a domain name for every conceivable consumer product out there why not catalytic converters too?

http://www.catalyticonverters.com/

:D

Good Luck

Lots of information on cats from Mercedes here:

https://mbwholesaleparts.com/StarTuned/pdfs/CatConvMar05.pdf

Includes cautions regarding aftermarket units.

The first question is: Why does it "need a new cat"?

Duke

Just buy a universal cat and have a shop install it. You will save alot of money. You can buy a universal Catco cat on Ebay for about $50 shipped.

Thanks everyone for these great comments!!

I bought the 400Es exhaust system from Timevalve and they were my 2nd call on this project. They no longer resell cats and referred me off to another vendor. The suggested vendor doesn’t sell to end users.

The shop said the cats are plugged. I should have asked how they determine this but didn’t think to do so. The shop has always been credible. I also remember another member’s tale of agony related to troubleshooting what turned out to be a plugged cat. Seems replacing it is an efficient means to NOT have to troubleshoot a bunch of other stuff.

In the really good article Ikchris referenced below, there is a nice detailed overview of cats. https://mbwholesaleparts.com/StarTu...atConvMar05.pdf One of the areas covered is how to test a cat for different kinds of failures.

In another part of the article they claim that one of the chief differences between after market and OEM cats is the volume of air flow. And the relative efficiency of the cat. They claim that the OEM cat has much higher values for both and that these values permit optimal performance for a longer period than does after market. Based on this my question is how do you find the specs for cats?

There is small cross section of cats for the 400E available on the web. Not every site has one for this model (I looked at all referenced above).

Here are some examples of what I found

http://www.catalyticonverters.com/MBE420MB22729294.html

not sure that this is correct but it’s the right engine and year. They state $494.14

These guys sell at 557.51

http://www.***************/cscmmp/mercedes/400e/catalytic_converter.html

These guys sell a brand called DEC at 525.95

http://www.***********************/mercedes~400e~catalytic_converter~dec~apwcbmmp~apwmb22726178ea3.html?apwcid=L1092232221W411a241dbe70 a&apwkwd=DEC+Catalytic+Converter+Mercedes+400E

These folks sell a brand called Miller for $655.72

http://www.***********************/mercedes_benz~400e~catalytic_converter~apwrmmp~apwh3000-84397b988aa.html?apwcid=L1092232221W411a241dbe70a&apwkwd=Mercedes+Benz+400E+Catalytic+Converter

Fastlane sells the Miller brand as well.

Is there a different colleciton of parts that come with these? As example are heat shields included with the cat? Are flanges and rings included?

Lastly, I'm intrigued the dbenz1’s comment to buy a universal cat. How does one adapt this to the vehicle? Are there specs for the size and form factor of cats? Or is the part standard enough so that it is fitted by displacement, or perhaps something similar?

Yes, it would be interesting to find out how your shop determined the car has "plugged cats." Given the cost of catalysts, this might be worth some shoe leather.

Cats have several failure modes. They can degrade chemically, which will usually show up as high emissions when everthing else checks out okay. They can also degrade mechanically (The honeycomb substate begins to disintegrate.), which is often indicated by a rattle. This can also cause high exhaust backpressure, which will result in poor high load performance. The matrix can also get plugged from combustion byproduct contaminants, particularly if leaded fuel is used or the engine has high oil consumption.

I think a lot of catalysts get replaced on little more than a whim, and that costs owners a lot of money, which could be better spent elsewhere. Before I ever replace a catalyst I would need a "preponderance of evidence" that replacement is actually necessary.

Duke

Restricted or 'plugged' converters are easy to test for by taking exhaust backpressure readings. Since few people have the equipment for testing backpressure, I suggest that you loosen the exhaust in front of the converter (usually easiest at the manifold) to create another path for spent gas to exit. A short test drive would then confirm or disprove exhaust restriction.

Even more important than verifying a plugged converter is discovering why the converter plugged up. If the converter melted internally due to a too-rich fuel mixture, the replacement will suffer the same fate if the cause is not corrected.

The most noticeable symptom of a plugged converter is lack of engine performance. The motor may start and idle normally, but will struggle to accelerate when the throttle is opened. It can feel very much like brakes dragging badly. If the restriction is bad enough, an engine can be held at WOT with no load, and it will struggle to gain rpm.

The worst I ever saw was an older Subaru owned by a college student. It was very difficult to start, and literally would not go over 15 mph or 1000 rpm. The owners complaint? It took too long to 'warm up'...refering to the length of time necessary for the engine to remain running and able to move the car without stalling.

Has anyone used either a DEC or Miller or other brand of cat??

I agree that it’s important to find out why it happened. The article above said the most common reasons were faulty 02 sensor or high oil consumption. The car doesn’t use oil and hasn’t used a measurable amount in the last 4 years. The major problem is lack of acceleration. The car is pokey below 3000 rpm and that is extremely uncharacteristic of the m119. it also has an odd miss fire that only occurs after the car has been sitting unused for a few days. If used daily it never misses but is pokey.

If the engine has good power above 3000 rpm, then the converter is not plugged. Engines are, in simple terms, big air pumps. They draw air in, mix it with fuel, burn the mixture, and pump the results out. The faster the engine runs (rpm), the more air in and exhaust out. With a restriction in the exit, the symptoms would first show up when the engine was running fast and trying to expell exhaust in large volume.

Upper end performance is not what it was. Lately it’s had about the same passing power as my ML.

Anyone?

You could also try the " oldest trick in the book ", to check for an exhaust restriction.
Connect a vacuum gauge to intake manifold vacuum, take the car for a drive, and observe the gauge readings when you go W.O.T.
Your gauge should be reading very close to 0 vacuum.
If the reading climbs while you're still accelerating, there is an exhaust restriction. ;)