W124 230TE - oil pressure gauge

adrianb

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W210 E320cdi Est. W124 E220Est, W124 230TE, W123 230TE (various) W123 200T.
I've just got myself back into the Mercedes family with an old 230TE auto. The engine runs smoothly enough, but the engine oil pressure gauge is a bit suspect. As soon as the key is in the ignition and the ancilliaries are on, the oil pressure guage shows "3" and it stays at "3" regardless. I'd like to kid myself that the engine has just been very carefully nurtured, with oil changes every 1000 miles since it was born, but it just can't be right can it in this old bus? Can anyone give me pointers as to where the pressure sensor/sender and plug are and what they'll look like / what I should be looking for. I've got a multi meter, so maybe I could test the output.

cheers

adrianb
 
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6pot

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my oil gauge is the same only dipping slightly when in traffic
 

television

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Sounds good and normal to me :D
 
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adrianb

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I was just a bit worried that it shows "3" even before the engine has turned over, but if this is just normal behaviour, I'm happy. Thanks for that.
 

television

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So it shows 3 when the ignition is on :confused:
 
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adrianb

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I am really impressed (and grateful:) ) with how quickly you all respond - and sorry you're not getting much help with your problem Malcolm. But WRT my problem, I've not explained it very well - the gauge shows "3" with the ignition on, but with the engine off and not running. If it was at "0" with engine off and ignition on, I wouldn't have been worried - just pleased:) - if a bit surprised.
 

coolhans

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Oil pressure

If the gauge is showing 3 with just the ignition on before you start the engine there is definitely a fault, it is probably the pressure sensor but could be the gauge. I'd get the sensor checked first.
 

Bolide

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It's not uncommon on W124s. I've seen temperature gauges that shoot up, drop down slowly and then wiggle about but the oil pressure pinned at 3 is the most common. I think it's a fault in the binnacle

Nick Froome
www.w124.co.uk
 
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adrianb

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Thanks Robert & Nick. I'll check this out further when I get a chance.
 

roadhog

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It's not uncommon on W124s. I've seen temperature gauges that shoot up, drop down slowly and then wiggle about but the oil pressure pinned at 3 is the most common. I think it's a fault in the binnacle

Nick Froome
www.w124.co.uk

I thought that a gauge staying at 3 pointed towards the over pressure valve in the sump? That said, mine was sticky for a while but a decent thump on the dash top would get it going again. It has since cured itself which is the way I like my car's faults. :D
 

teddycatkin

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Adrian---thats very normal when revs are up--whats the tick over at though?--If you really want to check its working properley--slow the tick over down very low after the engine has warmed up to normal temp you should see it move down a bit ---but do not leave the tick over too low afterwards !
Teddy
 

roadhog

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Adrian---thats very normal when revs are up--whats the tick over at though?--If you really want to check its working properley--slow the tick over down very low after the engine has warmed up to normal temp you should see it move down a bit ---but do not leave the tick over too low afterwards !
Teddy

His gauge reads 3 even with the engine off. I'd hazard a guess it's still at 3 on tickover?
 

television

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This is all electronic driven from the sender at the base of the oil filter,,the first thing to do is to take off this connector and see what the gauge does,,if nothing try grounding this wire and look again
 

Bolide

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The gauge reads zero with ignition off. So the rest position of the needle is zero. In this fault condition the needs pins at 3 with the ignition on. So something is driving the needle to 3

If the gauge reads 3 with the sensor disconnected I can't see it being anything other than a gauge fault

I've seen a couple of cars with this fault in the history where the sender has been changed and the fault was still present, so...

Nick Froome
www.w124.co.uk
 
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adrianb

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Rain and sorting out the battery flattening problems have kept me from looking into this yet, but I'll try to fit it in before the weekend.
 
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adrianb

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Found sensor and tried disconnecting - no change though. Should I just try earthing to the engine block? Pics show sensor connected (I think that was the correct one), and disconnected, plus reading from gauge, which remains the same while ignition on, regardless of engine running or not.
I've included another couple of pics of the three sensors on top of the engine. I wasn't sure which ones were which, but surely the LHS one shouldn't be soldered to one pin out of the three available? What do they do?
 

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television

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If there is no change when you earth/ ground it out, then the fault could be in the cluster
 

The Crooner

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The three pin switch is the signal for the electric fan, and the temperature guage.

Is your temperature gauge U/S?

The one like a spark plug with four pins sends temperature info to the ignition and injection systems, the cap fits any way round.

Tony

EDIT

The two way connector on the middle sensor should be where the two pins on the three way connector are missing.

The middle connector should have two vacuum pipes going to it.

If your engine is like mine.

Tony
 
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adrianb

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W210 E320cdi Est. W124 E220Est, W124 230TE, W123 230TE (various) W123 200T.
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Malcolm/all - I intended to connect the oil sensor cable to earth, but got carried away and connected it via the multimeter to earth instead. Doing that made no difference to the gauge readings, and I saw just over 6v from the cable. Should I also try connecting it straight to earth (it's been a long time since physics/reading lessons at school..)?

Tony - I think mine is similar, but a 1991 so a bit older, and a lot tattier than yours. I think it's the same colour though. For what it's worth the VIN is WDB1240832F174909, (I think) the engine no.is 102982 22 197893. It is a 4sp automatic, with no air conditioning.
Should I try shifting the centre connector to the two pins from the center sensor to the LH sensor? The temperature reading seems fine, and the fan is the viscous coupling version. Is it likely there are two vacuum pipes floating somewhere around that have been disconnected? Could this be why my central locking is playing up?

Some Thing
While nosing around and digging out dirt/berries/leaves etc from some of the drain holes (thank you again Malcolm) I came across some kind of plastic socket cover, just lying loose next to the battery - does anyone have any idea what this might be for? I put it on top of the battery to give some idea of scale. It doesn't look very Mercedes like.
By the way, I think the red cable and fuse on the left is part of my antenna/battery drain problems - it has a 30A fuse.

Thanks again all.
 

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