Oil pressure

1961-1968: a.k.a "Finnie" or "Heckflosse" models
190, 190D, 200, 200D, 220b, 220Sb, 220SEb, 230, 230S, 250SE coupe, 280SE coupe, 280SE 3.5 coupe, 220SEb cabrio., 250SE conv., 280SE cabrio., 280SE 3.5 Cabrio., 300SE, 300SE coupe, 300SE conv., 300SEL
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dynamike
S Class
Posts: 75
Joined: Thu 27 Oct, 2016 8:35 am
Model you own: w111
Location: Brisbane, QLD

Oil pressure

Post by dynamike » Thu 23 Nov, 2017 9:38 am

I recently noticed my oil pressure drops to 40 (from 45 max) when I'm in gear and stopped. As soon as I rev the engine or shift into neutral it goes straight back up to 45. My initial thoughts were idling speed too low but considering it's going up in neutral I'm not so sure.
low oil pressure.jpg

Couple of possibly related notes:
I only noticed it this week but it's possible this has been happening for a while
I minimally adjusted the idling and mixture screws on my Zenith carburetors last week.
Engine may have overheated for less than 5 minutes after coolant change and thermostat not opening in time a couple of weeks ago.
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1965 220 Sb Sedan
1962 220Seb Sedan (stripped for parts)
http://ozbenz.net/viewtopic.php?f=9&t=23626

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Bartman4800
300 SLR
Posts: 1764
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: Oil pressure

Post by Bartman4800 » Thu 23 Nov, 2017 10:22 am

The oil pressure needle should be pegged to the top when the engine is cold (idling or revved up)

When the engine is warmed up (and the oil is thinner) the pressure is allow to drop when idling. Nothing to worry here.
It should rise to full again when you increase the revs.

Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

User avatar
dynamike
S Class
Posts: 75
Joined: Thu 27 Oct, 2016 8:35 am
Model you own: w111
Location: Brisbane, QLD

Re: Oil pressure

Post by dynamike » Thu 23 Nov, 2017 1:48 pm

Thanks Bart. That's reassuring. What engine oil are you using for yours? I'm currently going with Shell HX3 20W-50.
1965 220 Sb Sedan
1962 220Seb Sedan (stripped for parts)
http://ozbenz.net/viewtopic.php?f=9&t=23626

sebada
E Class
Posts: 57
Joined: Tue 28 Jun, 2016 6:17 am
Model you own: w111
Location: El Pinar, Uruguay

Re: Oil pressure

Post by sebada » Fri 24 Nov, 2017 12:31 am

Hi,

Bart is right.

Another thing that happens with oil pressure is that oil viscosity decreases with use beacuse of additive shear and fuel contamination, so it's normal to have less oil pressure when the oil has some kilometers of use.

Regards

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