solitairECLASS

Hi,I drive a 1998 e320 4matic with only 131K km on it...sorry if my english is bad, im french speaking.

The problems started a few weeks ago, I first notice that, when I was parked ,the temperature would easily jump to 90 and then go back at 80 as soon as I hit the road. It wouldn't take time for the temperature to rise, everytime I would slow down or park my car and leave the engine running... but it never got higher than 90. I though it was pretty unusual since im driving this car for a year and it never happened before, but I didn't actually took great care of it since it was driving just fine. A couple of days after I notice that my car seemed to be slower than usual, and consuming more gas than usual...

The week after, I was driving at 150km/h on the highway and my check engine light came on but beside the fact it was slower to accelerate than normal, everything seemed to be fine. I don't take my car everyday, I use it mostly during the weekends so it took me about 5 days til I hit the road again with it. When I did, I was about to go on the highway but I was unable to reach over 80km/h...some cylinder seemed to misfire!!!

I stopped the car on the side of the road then waited and re-started it, I was able to drive back home safely. I took it around the block to test it a little bit and the problem seemed to occur just when I hit hard on the gas pedal, and if I push the gas pedal to the bottom I can ear a rattling noise coming from under the car, like under my seat, but this happen just when I push it to maximum, then the check engine light start flashing and the car misfires.

I took the code reader and it gave me p0304,p0305,p0306 wich are cylinder 4, 5 and 6 misfires. Because of the rattling noise coming from under the car ,when I hit hard on the gas pedal, I suspect that the problem is probably related with the catalytic converter, but catalytic converter don't break by themself !! What could have damage my catalytic converter, how can I know if its the CAT on the driver side or the one on the passenger side that is defective ? If it's not the CAT would you have an idea of what can cause those symptoms ? If I erase the codes I can drive it normally(well almost...like I said : less performance, take more gas !) until I push the gas pedal to the maximum, then it start misfiring again...

Thanks for your help and advice.

loubapache

I think you identify the problem well. It is most likely the driver side cat that is causing the driver side bank cylinders (4, 5 and 6) misfiring. Something in the cat has broken loose so you are hearing the noise. Then these loose particles restricted the flow when you hit hard on the gas pedal.

So you only got the three codes? No others?

solitairECLASS

yes those are the only codes that I got !!P0300, P0304,P0305,P0306... I tested it many times to be sure.(I have the UIF code reader for E and S-Classes.)

I wasn't sure of wich side was defective because I read somewhere that the CAT would block the cylinders of the opposite side ,I'm glad to know that this information was wrong ... I was really confused !

I'm about to sell the car and I have somebody who is waiting to see it, actually I receive an offer the same day it started to misfire !!So I want to repair it as soon as possible ... but I really want to fix it, I don't want to leave the problem into the next owner hands !!

I'm looking forward to buy a new CAT, but I don't know if I should buy one from my dealer (very expensive), one from catco(less expensive)or an universal cat (very cheap) and do some fitting,adjusting,welding...

What do you think of universal CAT ?? How my 02 sensors will react if I put an universal CAT instead of an OEM ?

loubapache

If you can know for sure which cat is making the noise, it would help. My bet is the second one (bank 2 cat 2, the one on dirver side near in the back. Your car has 4 cats). If that is the case , there are some nice universal replacement for it like the Magnaflow 53005. Dealer cats are very expensive. Search various forums about the successful installation of Magnaflow 53005 in the E class and make your own decision.

Would you PM me where you are, the car information, and your askng price? Thanks,

solitairECLASS

Ok so I went to hit the CATS with my palm, as you suggested, but nothing seems to be wrong... is it supposed to be obvious ?? Could it be just blocked a little bit but not totally broken ?? cause one makes a little, almost inaudible vibrating sound, but thats it ... I can't even be sure if it's the CAT or something else !! This problem is giving me serious headache !!
If its not the CATs what else could it be ??

Is there anyway that I can find a plan of my exhaust system on the net ?

loubapache

Since you heard the noise, something must be making it so you need to isolate it.

Here is the exhaust diagram for your car. The two shown are the back cats (the two front ones are under and to the rear of the engine).

solitairECLASS

Thanks again for your help, I really appreciate !!

Those CATS are the one I hit yesterday, I guess I will have to somehow disconnect them and take a deeper look because I can't tell just by hitting them with my palm, beside a little vibration from the one on the driver side, they seem fine !! But there's a little hole in the box number 14 on the diagram...

Could it be something else than the CATs ?? Is there anything else that could cause misfires with a kind of rattling noise when I push the gas pedal to full throttle (but only on the road, even if push the hardest I can in the garage it won't make the rattling sound) ??

loubapache

It really depends on what the rattling noise comes from. There are other possible causes but not with rattling noise unless it was just some loose exhaust rattling noise. If you do check the Cat, you can try to loosen the exhaust pipe so some gas can leak.

One thing you can check is the MAF (a weak item for the model). Try to disconnect the plug. You will get some CEL codes but at least you can see if it still misfires.

I re-read your OP and the heating issue could be another cause. Are you loosing any coolant?

solitairECLASS

As a matter of fact : yes ! I saw some leakage coming from an hose when I changed my front-left axle-boot , and it was the same day I notice the temperature increase...but it was not a big leak though, but yes, i'm pretty sure it was from a coolant hose !!!

For the rattling sound, it sounds more like a bicycle chain falling off and its clearly coming from under the driver seat or pedals,somewhere under the driver...My MAF seems fine I've already tried what you just ask, it was my first thought because I know they're problematic on w210.

I've read many forums to see what it could be and everything seems to lead to a CAT problem, and beside the fact that my CATs looks fine when I hit them with my hand, I got every other symptoms !! Seriously...i'm kinda lost !

solitairECLASS

Ok so it was really the driver side CAT that was the problem, I took it off yesterday and the 1st CAT was all broken inside and the second one was jammed...

So now I have 2 cats to replace, I think i'm going to buy an OEM one or a direct fit from catco, wich includes the two CATs...is there any difference between the ones for the 4matic and the RWD ? I found one for RWD cheap and not far from where I am, as I look at it picture it seems to be same, am i wrong ?

ohlord

eastern cats has oe universals that can be spliced in.Do you need cats where you are located?

solitairECLASS

Hi,

I already bought my new cats, and its already installed...My Benz is finally back on the road !!

Thanks everyone for your help.

ohlord

glad to have you and it back on the road