W140 loss of power when hot - Mercedes-Benz Forum
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post #1 of 2 (permalink) Old 06-13-2019, 02:42 PM Thread Starter
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Date registered: Jun 2019
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(Thread Starter)
W140 loss of power when hot

I have 1997 S320 LWB. the car runs fine when cold in the morning but after driving for 20 mins engine loses power .the oil pressure gauge drops to zero and stays there most of the time .problem starts when temperature is reached 90.
I changed the AMS it didn't work then I changed fuel pump and filter nothing happened .I read it could be the oil sender so I changed it but problem still exist
I asked my mechanic to change the oil pump but I was told for that engine has to come out and if problem still exist after that it means engine has serious issues probably replacing the engine
So I am not sure what to do now
get the oil pump change?
get a new engine?
get rid of the car?
Umair Bhatti is offline  
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post #2 of 2 (permalink) Old 06-13-2019, 03:11 PM
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Date registered: May 2019
Vehicle: 1994 s600 coupe
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get the car scanned with a modern scan tool, the mechanic will read the live data and find out what it is.
it sounds like when it comes out of open loop into closed loop it stalls.
i.e. it may have a vacuum leak that the car can live with in open loop while rich on warmup mode,
but not afterwards when it goes into closed loop and leans the mixture a bit more.
or perhaps, it's getting hot and boiling the fuel, i.e. vapor lock,
or fuel pump/fuel pump relay/fuel filter is shot ?
fuel lines ??
but first a complete check of all sensors and live data is in order
1994v12 is offline  
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