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Discussion Starter #1
So I just did quite a bit of work to my 2000 E430. I did the water pump, hoses, Thermostat etc. I also swapped both engine mounts out on the same day. Ever since doing all this stuff the engine is quite rough and noticeable louder, mostly at low RPMs while under load/ acceleration. The engine isn't misfiring or anything it just feels and sounds more abrasive if that makes any sense. I was thinking it had to be something to do with the engine mounts so I got back under there and inspected them hoping to find something obvious, but I couldn’t see anything. Both mounts are lined up correctly and all the bolts are nice and tight. I’m kind of at a loss right now. Any ideas? Thanks in advance
 

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1998 E320 base sedan @ 160kmiles
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Hello :)

After engine mount replacement, you need to adapt the Engine computer to re-interpret the signals that come from the crankshaft position sensor.

From Startek:

After the replacement of the ME-SFI control module, CKP sensor (L5), starter ring gear or motor mount, a sensor adaption must be performed:
  • Engine coolant temperature approx. > 70 oC,
  • Drive vehicle on road.
Vehicles up to 01/98:
  • With selector lever in position 4: Increase engine rpm to approx. 2,500 rpm and then coast until engine rpm is approx. < 1,500 rpm.
  • With selector lever in position 2: Increase engine rpm to approx. 6,100 rpm and then coast until engine rpm is approx. < 4,100 rpm.
Again increase engine rpm to approx. 6,100 rpm and then coast until engine rpm is approx. < 3,000 rpm.
- Using the HHT, determine if VSS sensor adaption has taken place.
Vehicles as of 02/98:
  • With selector lever in position 3: Increase engine rpm to approx. 2,100 rpm and then hold a 50% engine load for approx. 30 seconds.
  • Using the HHT, determine if VSS sensor adaption has taken place.
 

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1972
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So I just did quite a bit of work to my 2000 E430. I did the water pump, hoses, Thermostat etc. I also swapped both engine mounts out on the same day. Ever since doing all this stuff the engine is quite rough and noticeable louder, mostly at low RPMs while under load/ acceleration. The engine isn't misfiring or anything it just feels and sounds more abrasive if that makes any sense. I was thinking it had to be something to do with the engine mounts so I got back under there and inspected them hoping to find something obvious, but I couldn’t see anything. Both mounts are lined up correctly and all the bolts are nice and tight. I’m kind of at a loss right now. Any ideas? Thanks in advance
What brand are engine mounts?
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E320
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Double check the motor mounts are installed properly and the little notch is correctly slotted in the motor mount bracket on the engine side.
 

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Registered
1972
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6,740 Posts
Hello :)

After engine mount replacement, you need to adapt the Engine computer to re-interpret the signals that come from the crankshaft position sensor.

From Startek:

After the replacement of the ME-SFI control module, CKP sensor (L5), starter ring gear or motor mount, a sensor adaption must be performed:
  • Engine coolant temperature approx. > 70 oC,
  • Drive vehicle on road.
Vehicles up to 01/98:
  • With selector lever in position 4: Increase engine rpm to approx. 2,500 rpm and then coast until engine rpm is approx. < 1,500 rpm.
  • With selector lever in position 2: Increase engine rpm to approx. 6,100 rpm and then coast until engine rpm is approx. < 4,100 rpm.
Again increase engine rpm to approx. 6,100 rpm and then coast until engine rpm is approx. < 3,000 rpm.
- Using the HHT, determine if VSS sensor adaption has taken place.
Vehicles as of 02/98:
  • With selector lever in position 3: Increase engine rpm to approx. 2,100 rpm and then hold a 50% engine load for approx. 30 seconds.
  • Using the HHT, determine if VSS sensor adaption has taken place.
While adaptation reset helps with misfire detection it does not change overall feel.
 

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Discussion Starter #8
I’ll check the trans mount, I have a new one, I’ll also look into that adaptation thing a bit more. I lifted the motor quite a bit to get the mounts in, is there anything that could have got messed up while lifting the motor.
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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I’ll check the trans mount, I have a new one, I’ll also look into that adaptation thing a bit more. I lifted the motor quite a bit to get the mounts in, is there anything that could have got messed up while lifting the motor.
What was the reason that you decided to replace the mounts ? Rough, shaky idle ?

Just drive around a while and do the adaptation.
Also make sure you did not knock a vacuum hose or two while removal / installment of the mounts or water pump. Check your sensor readings like the coolant temp sensor etc :).

Here is some reading about the adaptation.
 

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Discussion Starter #10
Update: So I'm still scratching my head trying to figure this one out. I removed both motor mounts again, inspected them and then reinstalled them. I can confirm they are installed properly and torqued to the proper setting. I also replaced the trans. mount to rule that out. So at this point im thinking this is not related to any of the mounts. So I've directed my focus back to the front of the motor. My latest suspicion is the belt tensioner which was also replaced with the water pump. It definitely feels like there is some friction coming from somewhere, but not all the time. This rough feeling and sound only seems to start at about 25% throttle and stays constant through the other 75. It does not get worse or better depending on engine speed. I can't seem to duplicate this symptom in park with the hood up, it feels like there needs to be load on the motor. Does anyone have any experience with a belt tensioner acting like this or have any other suggestions. Could a belt tensioner spin have any symptoms like this? any help would be much appreciated, thanks
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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Does it make any difference with the compressor engaged / disengaged ?

I do not think it is something to do with the tensioner, as it would have caused the the same issues when you increase the rpm with engine load or no load.

You can rule it out by installing the old one temporarily, if you still have it.
 

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Discussion Starter #12
No there’s no change with the AC compressor disengaged, and I got rid of the old tensioner. I think my next step is to take the fan off to rule that out, then try and find another tensioner to see if that fixes it.
 

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1998 E320 base sedan @ 160kmiles
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You can take the fan out to test, but does the fan care or know if the engine is under load ?
Have you checked your flex discs, propeller shaft play ?
 
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