E420 Tranny Clunk and crazy volume pot

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E420 Tranny Clunk and crazy volume pot - 12/14/2007 8:33:28 PM    DTB 420 Sport   Posts: 4 Joined: 12/14/2007 Status: offline Hi all, I am a new 1997 e420 sport owner. I have had serveral Mercedes and recently had my 85 300d totaled with me in it. It took a good hit and I walked away. Picked up a 1997 e420sport with 89,000 miles. Took it in for detailing and they cleaned the engine and got water into two cylinders. The next day it was running rough on six, and I swung it over for an oil change and look. Blew out the cylinders and it was fine. All else looks clean for the most part. Two issues so far. Intermitant clunk from the tranny under load. Not very predictable yet. The dealer wants $350 to do the tranny service which may be in line or may not be. It is 5 degrees in mn so I am staying away from my own work. Problem 2 is the volume on the stereo goes crazy once in a while while changing volumes. It sudenly goes up and blows my ears off. Great fun on the ride into work. I must say after owning and working on the older Mercedes, I am slightly intimidated by this beautiful machine. Even if it lasts a week it's been fun. Thanks Post #: 1

RE: E420 Tranny Clunk and crazy volume pot - 12/15/2007 8:42:51 PM    vytamenc   Posts: 318 Joined: 1/28/2006 Status: offline could be a few problem with your trans. one there my be a bad sprag(roller clutch) to check it  force a down shift 5-3 or 4-3 if it down shifts hard then there is a bad sprag(requires the trans being pulled and disassembled. second excessive clearance in a clutch pack mainly b1 if my memory serves me right but either way i would recommend taking it to the dealer they will need to hook the star to it and read for any codes and check fill cycles of these clutches and bands. _____________________________ diagnosis ten times to repair once (in reply to DTB 420 Sport) Post #: 2

RE: E420 Tranny Clunk and crazy volume pot - 12/15/2007 8:46:12 PM    vytamenc   Posts: 318 Joined: 1/28/2006 Status: offline oh almost forgot you car has whats called speed sensitive volume control i bet the volume increses when you steep on the gas and goes down when you let off? its normal you paid for that option!!!!! _____________________________ diagnosis ten times to repair once (in reply to DTB 420 Sport) Post #: 3

RE: E420 Tranny Clunk and crazy volume pot - 12/16/2007 12:24:42 PM    DTB 420 Sport   Posts: 4 Joined: 12/14/2007 Status: offline Thanks for the input. Tried shifting down and up. It seems to have no problem making the shift but at times will make a clunk sound right after shifting. I am going to take it over and have the tranny fluids changed etc. I thought $350 was steep but it is less steep than a new tranny. The volume thing is strange. It's like the knob does not respond to the direction you turn it at times. Turns up when it should turn down. Thanks for the input, any other ideas great, I will let you know, TB. (in reply to vytamenc) Post #: 4

RE: E420 Tranny Clunk and crazy volume pot - 12/16/2007 3:08:49 PM    braucher1   Posts: 17 Joined: 12/16/2007 Status: offline have a competent technician with SDS scan your car and look at trans adapts. this will give a general state of health of your transmission. these trannys are the 722.6 models that have lifetime fill...yea right...service every 60k if not sooner. anyways, if the adapts look ok, you have no actual shift feel problems, the clunk is driveline related. flex coupler-mounts-bushings all must be checked. HTH _____________________________ dan braucher braucher service inc braucherservice@gmail.com (in reply to DTB 420 Sport) Post #: 5

RE: E420 Tranny Clunk and crazy volume pot - 12/27/2007 2:03:36 PM    DTB 420 Sport   Posts: 4 Joined: 12/14/2007 Status: offline Bad news, the dealership ran Adaptation data and the negative data was as follows 02 Accel. 2-3 Nm 210 210 03 Accel. 3-4 Nm 210 210                        210  51                        57   -72 12 Accel. 5-4 Nm 12   -210                        -54   174 This appears to be the kiss of death. The technician at the dealership says he usually sees catastrophic failure where the car stops. It either goes or stops. Any thoughts would be appreciated. It will be on ebay soon unless I can figure out a reasonable alternative. (in reply to braucher1) Post #: 6

RE: E420 Tranny Clunk and crazy volume pot - 12/27/2007 3:41:52 PM    braucher1   Posts: 17 Joined: 12/16/2007 Status: offline 180 is the MAX allowed on adapts. doesnt matter wether its positive or negative. if yours are at 210 as you mentioned, its time to pop a trans in that sucker. factory rebuild-factory fluid only!!!! you may have the fluid flushed and it may go longer, but the -210 indicates a mechanical problem. positive numbers indicate clutch wear(normal to a point.) and negative indicates a mechanical issue, in most cases. from the looks of it yours must clunk in 1-2 upshift?    doesnt really matter, but its cool to know how it works. dont feel bad, 7 outta 10 722.6's out there need replaced.... _____________________________ dan braucher braucher service inc braucherservice@gmail.com (in reply to DTB 420 Sport) Post #: 7

RE: E420 Tranny Clunk and crazy volume pot - 12/27/2007 5:49:47 PM    DTB 420 Sport   Posts: 4 Joined: 12/14/2007 Status: offline Thanks for the feedback. Next question, if I did not have to go to my job during the day I would rebuild the tranny myself head to toe. I don't have the time and it is cold in MN. Is it possible to have it opened up and just repair the worn and broken parts. I did this on another Mercedes tranny and drove it for 100,000 miles before I rebuilt it. I found a rebuild book on the 722.6 and it states this is a simple tranny for a Mercedes. Any thoughts. I have been able to drive these cars because I have been willing to go the alternative route and still do it right. Any suggestions, TB (in reply to braucher1) Post #: 8

RE: E420 Tranny Clunk and crazy volume pot - 12/27/2007 6:57:52 PM    braucher1   Posts: 17 Joined: 12/16/2007 Status: offline i believe that there is over 5k worth of updates to the 722.6 if you were to tackle it yourself. not worth it. plus no warranty. the problem with a lot of these 722.6 is they updated a thrust bearing inside to a torrington. the thrust bearing wears out and can damage the case and other parts beyond feasible repair. also i believe that the updated valvebody requires that a new tcm be installed. ask the dealer parts guy. these trannys are simple..yes. thay are also @##$ing trash. believe me...the factory remans are a cheap alternative to diy. why dont you pop it in yourself instead? we work on these cars all day long and NEVER EVER rebuild trannys. the warranty is to good an fac remans, and liability is shitty on doing them yourself. lots of horror stories on these trannys. _____________________________ dan braucher braucher service inc braucherservice@gmail.com (in reply to DTB 420 Sport) Post #: 9

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