M103 oil pressure

[Benz in Brazil]

Last night I noticed that the pressure gauge on my W124 dropped quite low once the motor had warmed up.

When cold, and in 'Drive' the marker sits at 1 when I press the accelerator it jumps to 3. However, when the motor's warm it drops to nearly 0 then, as per normal, jumps to 3.

I change the oil regularly, the last change was 7,000kms ago. I also changed the filter (Hengst). My car was serviced by a MB 'stealership' in Brasilia up to 86,000kms and is now showing 107,000kms so I doubt it's an issue with the motor itself.

Could it be something to do with the pressure sensor or something as daft as a fuse?

Regards from sunny Brazil

 

[grober]

Nothing to worry about if the pressure rises with the revs. Lower pressure when warm just reflects the oil "flowability". What is the spec of the oil you are using 10w40 ?? Problem with the sensor is usually a bad connection with the sensor wire-cleaning the connector pin +socket usually restores function.

 

[Benz in Brazil]

I use Texaco Ursa TDX in both of my cars but I've never noticed this behaviour in my W116/M110.
http://www.texacoursa.com/products/index.html

BTW, Ursa is also recommended for MBz passenger cars by MBz Brazil.

 

[television]

For what they cost you could try a new sensor,they can go out of spec and get non linear, but as grober said its more important to be at 3 when driving

 

[grober]

From what I can gather Texaco Ursa TDX is 15w-40 motor oil primarily designed for turbo charged diesel engines but meets MB 229.1 specs for gasoline engines. Sounds fine for both your cars. Why there's difference between the 2 engines I don't know maybe something to do with designed engine operating temperature, bearing clearances, oil filter design or even the location of the oil pressure gauge pickup point in the oil gallery. All I can say is that you have nothing to worry about as far as the w124 engine is concerned since the oil pressure gauge readings are well within values expected. Hopefully some other forum members with this engine will confirm this shortly.

 

[Benz in Brazil]

You know, a possible reason it that as Ursa is good at keeping the engine clean, maybe some muck has been dislodged from around the sensor area.

My M110 also runs cooler than the M103, in fact, about 10C or so.

 

[KLP 92]

Change the sensor.

I had the smae issue with my SEC, i was extremely worried about the needle floating under the 1 bar mark on idle.

I changed the oil pressure sensor and the oil pressure now sits on 1.75 bar when hot

If it still goes down to 0 after a new sensor i would have the compression checked and possibly the oil pump changed. 0 is too low, even in the operation manual it states 0.3 should be the lowest.

 

[Benz in Brazil]

Right, I've decided as it must be the pressure sensor thats dicky as everything else is OK. Now, the thing is I can't find it. There is almost no reference to it in the Haynes manual I have except for in the wiring diagram. I'll have to wait for the motor to cool before I can poke around.

Could someone point me in the right direction?

Thanks for all the advice so far.

 

[television]

I think that it is 524 in the link. It has to be in the main oil gallery

http://www.detali.ru/cat/oem_mb2.as...&L=765.702&CT=M&cat=032&SID=15&SGR=001&SGN=01


this is for all of your car

http://www.detali.ru/cat/oem_mb1.asp?TP=1&F=116020&VIN=

 

[Benz in Brazil]

Thanks, I'm familiar with this site. It is a wealth of useful knowledge...although I hadn't thought of looking on the links you sent through. Thanks again.

 

[television]

It can only be water in the top where the head sits on the block, it cant be in the sump. the pump outlet sits just above the sump and this is where the main oil gallery is, the only pressurised part, so the sensor has to sit somwhere just above the sump.

Sorry to go on, but not easy to explain

 

[LastMinute]

The oil pressure sensor is on the filter fitting. Item 44 here.

 

[grober]

Following on from Malcolm's post the oil pressure sender is normally found beside the oil filter. It will look very like item 458 on the last picture here. http://www.detali.ru/cat/oem_mb2.as...&L=765.702&CT=M&cat=032&SID=18&SGR=001&SGN=01
Unfortunately the part no is not listed. If the oil filter is the cartridge type as in LastMinutes post then the layout is slightly different.The connection is normally a threaded brass pin- test you have the correct connection by temporarily disconnecting it and the monitoring the oil pressure reading. The filter on these engines is located towards the rear of the engine on the inlet manifold side.

 

[television]

The oil pressure sensor is on the filter fitting. Item 44 here.

This car has the 110 engine

 

[television]

Following on from Malcolm's post the oil pressure sender is normally found beside the oil filter. It will look very like item 458 on the last picture here. http://www.detali.ru/cat/oem_mb2.as...&L=765.702&CT=M&cat=032&SID=18&SGR=001&SGN=01
Unfortunately the part no is not listed. The connection is normally a threaded brass pin- test you have the correct connection by temporarily disconnecting it and the monitoring the oil pressure reading.

Thank you very much, not at my best after 77 post today

 

[Benz in Brazil]

I think there has been some confusion here. The car with the dodgy oil pressure reading is the W124/M103 not my W116/M110.

But, still thanks everyone at least I'm on the right track again. The oil filter/cooler link has sorted out my doubt.

Thanks gents!

 

[television]

I think there has been some confusion here. The car with the dodgy oil pressure reading is the W124/M103 not my W116/M110.

But, still thanks everyone at least I'm on thr right track again. The oil filter/cooler link has sorted out my doubt.

Thanks gents!

Grobers post in number 13 is correct

 

[Benz in Brazil]

Well, I changed the sensor this morning, it was quite expensive at R$250,00, anyway now at around 80-85C in Drive, ticking over the needle is at about 1.2 in Neutral it shows about 1.5.

So it seems the problem is solved. No dramas to worry about...thankfully.

 

[LastMinute]

quite expensive at R$250,00

List price here is GBP 58.75, which is a shade under BRL 200 (at the bank rate, I think).

 

[Benz in Brazil]

If i were to import it, it would cost the same. Sometimes though, importing bits and pieces so so much cheaper.