87 429 SEL Vacuum Leak or Fuel Pump
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87 429 SEL Vacuum Leak or Fuel Pump
I have an 87 420 SEL that has a few issues. The main one is fuel delivery; secondly, the transmission leaking and lastly the drivers’ side window will not go down.
It seems to be a common issue on this model to have some sort of ruff idle and or hesitation when accelerating. I have changed the Air Filter, Spark Plugs, and fuel filter but not the pumps. I am thinking that only one pump is cutting out on at regular intervals, since the car will run when at low RPM but it is like getting a turbo boost when the second pump comes on. I initially thought that it was a fuel contamination issue but after using Sea Foam and other fuel cleaners that did not solve the problem. I also have read that there is a fuel pump relay that may cause this issue as well, any comment on this.
My second issue is the transmission. When I initially got the car, it would slip while decelerating to make a turn or just jerk very hard when it is put into gear. The transmission does have a slow leak but I have routinely had the fluid changes to keep the levels in check.
Lastly, the driver side window motor keeps blowing the fuse. I think it is the regulator not the motor since it was working fine but it blew its first fuse when going and has not worked since. Any help is greatly appreciated. Oh yes I do get under the hood quite a bit, gotta love that German Engineering.
It seems to be a common issue on this model to have some sort of ruff idle and or hesitation when accelerating. I have changed the Air Filter, Spark Plugs, and fuel filter but not the pumps. I am thinking that only one pump is cutting out on at regular intervals, since the car will run when at low RPM but it is like getting a turbo boost when the second pump comes on. I initially thought that it was a fuel contamination issue but after using Sea Foam and other fuel cleaners that did not solve the problem. I also have read that there is a fuel pump relay that may cause this issue as well, any comment on this.
My second issue is the transmission. When I initially got the car, it would slip while decelerating to make a turn or just jerk very hard when it is put into gear. The transmission does have a slow leak but I have routinely had the fluid changes to keep the levels in check.
Lastly, the driver side window motor keeps blowing the fuse. I think it is the regulator not the motor since it was working fine but it blew its first fuse when going and has not worked since. Any help is greatly appreciated. Oh yes I do get under the hood quite a bit, gotta love that German Engineering.
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Joined: Jan 2007
Posts: 497
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From: Canton Michigan
1991 Mercedes-Benz 560 SEL
I have an 87 420 SEL that has a few issues. The main one is fuel delivery; secondly, the transmission leaking and lastly the drivers’ side window will not go down.
It seems to be a common issue on this model to have some sort of ruff idle and or hesitation when accelerating. I have changed the Air Filter, Spark Plugs, and fuel filter but not the pumps. I am thinking that only one pump is cutting out on at regular intervals, since the car will run when at low RPM but it is like getting a turbo boost when the second pump comes on. I initially thought that it was a fuel contamination issue but after using Sea Foam and other fuel cleaners that did not solve the problem. I also have read that there is a fuel pump relay that may cause this issue as well, any comment on this.
My second issue is the transmission. When I initially got the car, it would slip while decelerating to make a turn or just jerk very hard when it is put into gear. The transmission does have a slow leak but I have routinely had the fluid changes to keep the levels in check.
Lastly, the driver side window motor keeps blowing the fuse. I think it is the regulator not the motor since it was working fine but it blew its first fuse when going and has not worked since. Any help is greatly appreciated. Oh yes I do get under the hood quite a bit, gotta love that German Engineering.
It seems to be a common issue on this model to have some sort of ruff idle and or hesitation when accelerating. I have changed the Air Filter, Spark Plugs, and fuel filter but not the pumps. I am thinking that only one pump is cutting out on at regular intervals, since the car will run when at low RPM but it is like getting a turbo boost when the second pump comes on. I initially thought that it was a fuel contamination issue but after using Sea Foam and other fuel cleaners that did not solve the problem. I also have read that there is a fuel pump relay that may cause this issue as well, any comment on this.
My second issue is the transmission. When I initially got the car, it would slip while decelerating to make a turn or just jerk very hard when it is put into gear. The transmission does have a slow leak but I have routinely had the fluid changes to keep the levels in check.
Lastly, the driver side window motor keeps blowing the fuse. I think it is the regulator not the motor since it was working fine but it blew its first fuse when going and has not worked since. Any help is greatly appreciated. Oh yes I do get under the hood quite a bit, gotta love that German Engineering.
Transmission could be worn however inspect the flex disc, center bearing and U-joint and keep an eye on the fluid level. If you have a low fluid condition this could cause it to slip and to bang into gears. Do you know where the transmission is leaking? Most of them only leak at the little cooler lines that run to the radiator.
As far as the window blowing fuses I am at a loss. I can only guess you must have a short in that circut that could range from a bad motor, too much stress on the motor due to bad regulator or even a chaffed wire that is grounding.
Deal with them one at a time, it makes it easier.
