Mercedes-Benz Forum banner

1 - 12 of 12 Posts

·
Registered
2003 C320 4matic
Joined
·
7 Posts
Discussion Starter #1 (Edited)
So.. i have a 2003 c320 4Matic. For the last month i have been having some issues. The car stumbles/hesitates/misses when i am accelerating. The problem only occurs once the car is completely warmed up(after about 20 minutes of driving or so). When i am cruising along at about 1500-2500 rpm is when it is the worst. the car shakes and jerks like its not getting fuel or maybe spark. When this "hesitation" occurs at the 1500-2500 rpm range i can hear sum sort of droning noise from behind me while im driving(i think this is coming through the exhaust but not positive)...Even at high speeds(over 3500rpm) the car hesitates, but i cant hear any noise through the exhaust. i have replaced spark plugs with ones from autohausaz, replaced fuel filter, and air filters. I tested fuel pump pressure(steady at 56 psi..even tested while driving with the problem occurring..still steady at 56 psi..) i cleaned the maf sensor. Thinking something with egr system since the problem only seems to happen in closed loop. No obdII codes. Very frustrating. Any suggestions would be very very greatly appreciated...
 

·
Registered
2003 C320 4matic
Joined
·
7 Posts
Discussion Starter #3
would ignition wires cause an issue only when the car is warmed up or would they cause a problem all the time if they were bad. Ive been watching volts through obdII for o2 sensors but maybe i need to look into diagnosing them better...would either of these cause me to hear this droning noise through the exhaust??
 

·
Registered
'07 C280 4matic, '06 530i, '98 ML320
Joined
·
1,562 Posts
partially clogged catalytic converter can cause that issue and the mentioned noise.

If I were you, I would focus on the O2 sensor and the catalytic converter. The more I read the symptoms, the more I am leaning towards the catalytic converter. If your car has less than 80K miles, cats would still be under warranty.
 

·
Registered
2003 C320 4matic
Joined
·
7 Posts
Discussion Starter #5 (Edited)
Cats

Yea.I've been thinking the converters because I can't think of anything else that would make that droning noise through the exhaust.i did a vacuum test and the pressure was steady at 19 in hg. When I rev engine and hold at 2500 rpms vacuum drops to about 14-15 and stays their until I let off throttle. Is this normal? Where is a good spot to tap in to check back pressure for exhaust? Of course car has just over 80000 miles so converter is not covered. Thanks for the replies...
 

·
Registered
2013 ML350 4matic and 2003 C240 4matic
Joined
·
33 Posts
I know this post is old, b ut I am having the exact same problem on my '03 240 4matic. what ended up being the problem? I assume it has been fixed by now.
 

·
Registered
2003 C320 4matic
Joined
·
7 Posts
Discussion Starter #7
marcanders-hesitation

Ended up being a very common problem on these cars. Check to see if you have a valeo radiator. if you do they were horrible radiators and bulletins were posted by mercedes that they were bad, but they wont do anything about it. if it has the Valeo radiator, they leak coolant into the trans internally in the radiator causing the trans to slip. if you caught it in time you can just replace the radiator and flush the trans and you should be fine. Hope everything goes good for you. let me know if you have any other questions..
 

·
Registered
2013 ML350 4matic and 2003 C240 4matic
Joined
·
33 Posts
Ended up being a very common problem on these cars. Check to see if you have a valeo radiator. if you do they were horrible radiators and bulletins were posted by mercedes that they were bad, but they wont do anything about it. if it has the Valeo radiator, they leak coolant into the trans internally in the radiator causing the trans to slip. if you caught it in time you can just replace the radiator aWnd flush the trans and you should be fine. Hope everything goes good for you. let me know if you have any other questions..
To snorwood1011... You were right and thank you!!! It was the radiator leaking fluid into the transmission. I got a new radiator and flushed the tranny and back to it's old self. Thanks for the info and I am appreciative of you sharing hat went wrong for you.

Marc Andersen
 

·
Registered
2003 C320 4matic
Joined
·
7 Posts
Discussion Starter #10
PCY

no problem at all. glad i could help. that was a very frustrating problem for me. Hope all goes well with the Benz.. come back to the site if you have any other problems.
 

·
Registered
2003 MB C320 4MATIC Wagon
Joined
·
2 Posts
I have an 03 c320 4matic... could i have the same issue? and how do i go about determining if its a valeo?
also, how much would a repair like this cost?
 

·
Registered
2013 ML350 4matic and 2003 C240 4matic
Joined
·
33 Posts
There are pictures of the Valeo radiator on this forum and it does have some unique identifiers, They have clamsp on the sides and the Behr radiaotrs have a wavy side. Ultimately, if your tranny is doing this, GET IT FIXED ASAP before you jack up your tranny any more. I did mine last week and was fortunate enough that it didn't cause any noticable damage but he said if it did, it would cost $5,000 for a new tranny. It cost me like $850 to get a new radiator and have the transmission serviced/flushed and this is at a local independent mechanic. If I did it myself, I know I would have saved money, but I don't know much about trannys and it was worth it to have him check it over. Good luck and tell us what happens!
 
1 - 12 of 12 Posts
Top