How do you replace the 'output shaft sensor' on W140 Mercedes V8?

[86560SEL]

Can anyone tell me step by step how to replace the 'output shaft sensor' on a W140 Mercedes? Mine in particular is a 1993 400SEL with the 4.2L V8. I would also appreciate a link on how to replace it. I did a search and couldn't come up with anything.

Thanks in advance!

Also, while I am here, how about the FPR on these cars? I was also told my problem could be the fuel pressure relay.

[86560SEL]

Apparently also known as "crank position sensor".

[pawoSD]

It is usually mounted on the back of the engine on the side or top with an allen bolt or two, protruding down near the flywheel ring. Not much to replacing other than locating, unscrewing, removing/unplugging, and reversing that with the new part.

[86560SEL]

Thanks so much. I will see if I can track it down. Hopefully someone can show me a photo. lol.

This has been such a headache.

[Frank Reiner]

Originally Posted by 86560SEL

Also, while I am here, how about the FPR on these cars? I was also told my problem could be the fuel pressure relay.

FPR= Fuel Pump Relay OR Fuel Pressure Regulator

[86560SEL]

Originally Posted by Frank Reiner

FPR= Fuel Pump Relay OR Fuel Pressure Regulator

Yeah that thing. LOL. Thanks!

Someone on another Mercedes forum had called it a fuel pressure relay, so that is where I got my poor information from. Sounds like I would rather it be the crank sensor, as it sounds easier to replace.

[Frank Reiner]

Originally Posted by 86560SEL

Yeah that thing. LOL. Thanks!

Someone on another Mercedes forum had called it a fuel pressure relay, so that is where I got my poor information from. Sounds like I would rather it be the crank sensor, as it sounds easier to replace.

Obviously, my response was not quite clear enough; FPR can refer to either a Fuel Pressure Regulator OR a Fuel Pump Relay.

You suggested that the "FPR" could be your problem. Just what, pray tell, is your problem??

As to replacement, either "FPR" will be easier than the crank sensor.

[MAVA]

It can be a 10 min job or a 24hr job...

w140 Rear Crank Position Sensor / RnR nightmare

1995 s500 crankshaft position sensor help - Mercedes-Benz Forum

Martin

[86560SEL]

Originally Posted by Frank Reiner

Obviously, my response was not quite clear enough; FPR can refer to either a Fuel Pressure Regulator OR a Fuel Pump Relay.

You suggested that the "FPR" could be your problem. Just what, pray tell, is your problem??

As to replacement, either "FPR" will be easier than the crank sensor.

lol, yeah, I knew what you meant. I was just saying someone had worded it to me wrong... at least I guess they did, I am confused. LOL.

Thanks for the additional info. I wasn't sure at all about how easy/difficult the FPR was to replace, but sounds good it is easier. I haven't don't much research on those... I thought it was something in the gas tank or something.

Originally Posted by MAVA

It can be a 10 min job or a 24hr job...

w140 Rear Crank Position Sensor / RnR nightmare

1995 s500 crankshaft position sensor help - Mercedes-Benz Forum

Martin

Wow.

Well the good news is I found another Mercedes mechanic locally that is new to the area with a good rep that can look at my car next week, so I guess that is where it will be going. He said they charge $70 per hour diagnostic, but would call it if it was going ot be more than an hour and it would be knocked down if I went ahead and had them repair whatever the issue is. I told him what I was told here and he said that sounds likely, so hopefully that will knock down the time spent on it there. I also mentioned that my valve cover gaskets are leaking again despite being replaced less than 2 years ago by a Mercedes mechanic. Hopefully that is not a high labor task to repair.