Puzzled by Transmission Problems
01-07-2008, 10:22 AM
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1996 E230 (W210)
Puzzled by Transmission Problems
Grateful for any steer/advice that you experts can give a newbie:
Whenever I drive off in the morning, there is a clunking sound as the car inches a long as if 1st doesn't want to engage. If on an incline (office basement parking), the revs just go up and the car refuses to move until suddenly the gear engages and then I lurch forward. The sudden gear engagement is normally accompanied by the "yellow exclamation point triangle" which goes off in a few seconds. The really mysterious part is that after a few meters, everything goes back to normal.
I have recently changed tranny oil and filter, and an independent workshop pulled down, inspected and cleaned the valve body. They also report that the "modulating pressure" is OK but the problem still persists. They recommend that we pull down the main transmission to have a thorough look.
I will probably let them do it in a few weeks time but is there anything else that may be causing this? electronics? torque converters? etc?
Grateful for any steer.....thank you
Whenever I drive off in the morning, there is a clunking sound as the car inches a long as if 1st doesn't want to engage. If on an incline (office basement parking), the revs just go up and the car refuses to move until suddenly the gear engages and then I lurch forward. The sudden gear engagement is normally accompanied by the "yellow exclamation point triangle" which goes off in a few seconds. The really mysterious part is that after a few meters, everything goes back to normal.
I have recently changed tranny oil and filter, and an independent workshop pulled down, inspected and cleaned the valve body. They also report that the "modulating pressure" is OK but the problem still persists. They recommend that we pull down the main transmission to have a thorough look.
I will probably let them do it in a few weeks time but is there anything else that may be causing this? electronics? torque converters? etc?
Grateful for any steer.....thank you
01-14-2008, 02:04 AM
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Grateful for any steer/advice that you experts can give a newbie:
Whenever I drive off in the morning, there is a clunking sound as the car inches a long as if 1st doesn't want to engage. If on an incline (office basement parking), the revs just go up and the car refuses to move until suddenly the gear engages and then I lurch forward. The sudden gear engagement is normally accompanied by the "yellow exclamation point triangle" which goes off in a few seconds. The really mysterious part is that after a few meters, everything goes back to normal.
I have recently changed tranny oil and filter, and an independent workshop pulled down, inspected and cleaned the valve body. They also report that the "modulating pressure" is OK but the problem still persists. They recommend that we pull down the main transmission to have a thorough look.
I will probably let them do it in a few weeks time but is there anything else that may be causing this? electronics? torque converters? etc?
Grateful for any steer.....thank you
Whenever I drive off in the morning, there is a clunking sound as the car inches a long as if 1st doesn't want to engage. If on an incline (office basement parking), the revs just go up and the car refuses to move until suddenly the gear engages and then I lurch forward. The sudden gear engagement is normally accompanied by the "yellow exclamation point triangle" which goes off in a few seconds. The really mysterious part is that after a few meters, everything goes back to normal.
I have recently changed tranny oil and filter, and an independent workshop pulled down, inspected and cleaned the valve body. They also report that the "modulating pressure" is OK but the problem still persists. They recommend that we pull down the main transmission to have a thorough look.
I will probably let them do it in a few weeks time but is there anything else that may be causing this? electronics? torque converters? etc?
Grateful for any steer.....thank you
01-14-2008, 09:30 AM
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1997 Mercedes Benz E420
A 1996 E320...
will have the older four speed automatic transmission, I believe.
You should also check the adjustment on the bowden cable which sends throttle position information to the transmission. If mis-adjusted, it can cause symptoms similar to what you have posted.
On my former W124 400E with the four speed transmission, this adjustment was at the firewall. Your transmission shop should be able to locate it.
One other possibility is a broken spring in the valve body, but from your report the value body has been opened and cleaned, right? If your modulator pressure is good, the value body is squared away, then barring excessive wear in the bands and clutches, the car should go...
Keep us posted
JR
You should also check the adjustment on the bowden cable which sends throttle position information to the transmission. If mis-adjusted, it can cause symptoms similar to what you have posted.
On my former W124 400E with the four speed transmission, this adjustment was at the firewall. Your transmission shop should be able to locate it.
One other possibility is a broken spring in the valve body, but from your report the value body has been opened and cleaned, right? If your modulator pressure is good, the value body is squared away, then barring excessive wear in the bands and clutches, the car should go...
Keep us posted
JR
01-14-2008, 09:53 AM
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1997 Mercedes Benz E420
One other thought is...
You mention the "yellow triangle" coming on; the car may also be experiencing an ASR fault. The ASR issues will usually initially come on, and be able to be cleared by a re-start, but will eventually get worse, much worse.
Essentially, when the ASR begins to fail, the car goes into "limp home" mode, so throttle response is reduced by +/- 70% and the car begins to engage the ABS because the system thinks you have a traction slippage problem. Lots of engine revs, but no real response in getting the car to move out, right? Then "bang" you hear a noise and off she goes?
You should get your codes read ASAP. Continuing to drive the car in either case can cause damage. Sorry to say, but if it is the ASR... repairs can be expensive.
Good luck,
JR
Essentially, when the ASR begins to fail, the car goes into "limp home" mode, so throttle response is reduced by +/- 70% and the car begins to engage the ABS because the system thinks you have a traction slippage problem. Lots of engine revs, but no real response in getting the car to move out, right? Then "bang" you hear a noise and off she goes?
You should get your codes read ASAP. Continuing to drive the car in either case can cause damage. Sorry to say, but if it is the ASR... repairs can be expensive.
Good luck,
JR
