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Mercedes S500 - W140 && S500 W220.
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821 Posts
Discussion Starter #1
Hi everyone,

After going through the regular checks, changing oil and state of denial,

Oil pressure on cold start is 3, and would drop down to 0.3 when engine temp is 90C at idle RPM.
If I rev up to 3K RPM, the pressure rises back to 3bars.

Is this behavior OK ? else should I try changing / repairing the oil pump for the m119.

( cam oil tubes are fine, Pressure sending unit is fine, wiring is fine )

Opinions appreciated please.
 

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W140 Moderator
"CHRIS" Merc 92 600SEL / Sold > 93 600SE / 93 S500 / 89 560SEL / 413CDI / B180-CDI /A170-CDI
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7,639 Posts
I could be wrong but to me this sounds like a faulty oil press sender unit ,mine was faulty after 2 month but i also had the lower wiring harness broken at the time ,dont know if it was coincidents or i just cop't a faulty oilpresss sender unit ,but yeah , check on that again ,oil press sender is cheap over there in the US .:thumbsup:

This thing here anyway ,dont ask me why but here they cost $180 .:
http://www.ebay.com.au/itm/Mercedes-r129-w140-Oil-Pressure-Sensor-2-pin-Oil-Filter-Housing-/271012898360?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f19a0a638
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
if the end caps break on the oilers they get stuck in the oil pans screen which slows down the flow of the oil.

also visually the oilers look good but you need to touch the back part to see if the end cap is still there
 

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Registered
Mercedes S500 - W140 && S500 W220.
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821 Posts
Discussion Starter #7 (Edited)
if the end caps break on the oilers they get stuck in the oil pans screen which slows down the flow of the oil.

also visually the oilers look good but you need to touch the back part to see if the end cap is still there
The end caps were all intact and thus the tubes were not changed.
Every tube was individually tested to ensure the cat is intact and they all were.
Every tube was individually rubbed for feel for any cracks .. there weren't any.

The mechanic seems to think, there is a problem with the oil pump ..
I want to understand if this diagnosis is correct ?
and if yes, then how can this be achieved ?
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
Honestly i dont know what to say. Have they hooked it up to manual pressure gauge? Because mine had a sending unit issue.
 
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