Oil Leak after slight overfill/ thicker hot oil/disconnecting warning light

d215yq

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Hi All,

Well I got a bit bored of the oil light coming on every few weeks (it comes on even when the oil is nearly 2/3rd full now) so put about a litre extra oil in and now it is overfilled. This has also coincided with a leak happening (yes I know, my fault but I was in a rush and the light is ****** annoying when driving at night and coming on regularly).

Does that mean a seal is bad or just that it will be fine by the time the level is correct/when i do an oil change to the correct level? I can't see where the leak is (collects in the tray but I think it's coming from top engine on air intake side (not exhaust side) as that side (above the engine mount) has fresh black oily residue. I will investigate and try to remove tray later to understand the extent/location.

It's also overdue an oil change so as the oil seems to go down more in summer than winter am I correct to buy 10W50 instead of 10W40 (keep the cold start protection but not have it leak/burn so much in hot weather). I was advised that 10W40 is too thin on an engine with not far off 300k miles on it anyway. Before the overfillign/leak it used about 50ml/1k miles winter and 200ml/1k miles summer on 10W40.

Can I also cut the wiring from the sump sensor and leave open circuit, or do I then need to complete the circuit to have the light go off permanently? I understand that may not be the brightest idea but now it comes on at 2/3 full I reckon I would have to keep adding 100-200ml at a time to keep light off and it under maximum (which is typically every 2 or 3 weeks) and it really isn't worth the bother, particularly as I understand it is better to be nearer the min than the max on this engine (indeed there is a big warning sign about overfillign it on the cap, and I can see why!)...and there is still the oil pressure gauge that works fine to "check" for oil...
 
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d215yq

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Actually on further investigation leak was diesel - the difficult hose i left when changing the others was dripping. It seemed it was mixing with old oil stains so was a little bit black but at source was diesel.

Took a long time but done it so now no.more hoses to do. Not why there are so many on that car...

As such can i leave the car a bit overfilled for a while. Its only a cm above max on dipstick? As ive removed tray and cleaned everything plan is to drive it a bit and make sure leak is fixed before doing an oil change when ill make sure its the correct level...
 
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d215yq

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I think a centimetre is about one litre , anyone ?

It cant be a litre over as i added 1l in total and it was 2/3 full before. Ive rechecked everything and theres no leak at all now as far as i can tell so it was the diesel pipes leaking not engine oil.

Oil pressure seems normal so will leave it be until oil change where ill put 10w50 so it will go longer hopefully before ovr sensitive light comes on...
 
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d215yq

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10w50? Not an MB spec then?

I got the idea from when I asked a couple of years ago that an OM603 will take anything so it's not really important what spec it is...is this not the case? I've always used the cheapest semi synthetic 10W40 on offer at the time (that always happened to have a merc spec that I think was better than the one required) but it does seem to use more oil in the summer than in winter so was thinking 10W50 would keep it good for cold starts in winter but be thicker when it's hot.

Is there a reason not to use that grade? In the owners manual there's the overlapping ranges you can use which means for the Mediterranean climate I could use anythign from 0W30 to 20W60 so it's not particularly helpful. Perhaps I just need to sort out the silly warnning light as that is causing all the problems as I only have from 2/3 to max to play with making the slight oil consumption more annoying. In my experience the warning lights on W124s are by far the least reliable part of the car; according to various warning lights over my 3 W124s I should have had about 100 times where I couldn't proceed and 3x new engines. In reality I've had 1 breakdown (failed alternator) which wasn't highlighted by the light designed to warn of exactly that scenario! I'd happily remove the lot and just enjoy worry free motoring but you never know if they might introduce a law here where they have to work to pass the MOT like they've done in the UK...
 

thebiglad

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I'm not familiar with the W124 warning lights, but it seems to me that the oil light is the thing causing you the most concern, so that's what I would be concentrating on resolving.

Is this warning light for oil pressure or oil level? If it's for oil pressure I would be changing the oil pressure switch, which is often the cause of flickering oil lights on many cars and cheap and easy to do.
 
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d215yq

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I'm not familiar with the W124 warning lights, but it seems to me that the oil light is the thing causing you the most concern, so that's what I would be concentrating on resolving.

Is this warning light for oil pressure or oil level? If it's for oil pressure I would be changing the oil pressure switch, which is often the cause of flickering oil lights on many cars and cheap and easy to do.

It's an oil level sensor. It was designed to come on at 1/2 for some reason and this now comes on at 2/3, which means there's about 2-300ml to play with which in summer gets used up in 1500 miles which for me means every 2-3 weeks. I can see the sensor so could replace it but imagine that could start oil leaks and bother as it has probably been in there for 33 years...

I think I'll just leave it be and do an oil change wit thicker oil and if it still annoys me I'll just cut the wires and go on oil pressure gauge. The lights are like the boy who cried wolf so I don't even pay any attention to them anyway unless I'm drivig long distance at night when they are annoying so have to find a way to make them go off.

Unless there's a fuse/wire somewhere that disconnects all the lights simultaneously? The brake light pad sensor comes on only when braking and turning right, the red brake light one comes on for 5 minutes after the handbrake is used, the washer light also comes on at 2/3rds full so teh capacity is effectively 1l instead of 3l... The coolant light was disconnected by a PO so I connected and found that is always on despite being full of coolant so disconnected again. Glowplug light never comes on but car still starts, alternator warning light didnt come on when the alternator failed...i think the faulty bulb is the only useful one that works. It's annoying as I used to be in the camp of investigate everything but now I wouldn't stop to check any gauge/light if it came on and would just assume it's another false alarm...
 

Hustler

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It's an oil level sensor. It was designed to come on at 1/2 for some reason and this now comes on at 2/3, which means there's about 2-300ml to play with which in summer gets used up in 1500 miles which for me means every 2-3 weeks. I can see the sensor so could replace it but imagine that could start oil leaks and bother as it has probably been in there for 33 years...

I think I'll just leave it be and do an oil change wit thicker oil and if it still annoys me I'll just cut the wires and go on oil pressure gauge. The lights are like the boy who cried wolf so I don't even pay any attention to them anyway unless I'm drivig long distance at night when they are annoying so have to find a way to make them go off.

Unless there's a fuse/wire somewhere that disconnects all the lights simultaneously? The brake light pad sensor comes on only when braking and turning right, the red brake light one comes on for 5 minutes after the handbrake is used, the washer light also comes on at 2/3rds full so teh capacity is effectively 1l instead of 3l... The coolant light was disconnected by a PO so I connected and found that is always on despite being full of coolant so disconnected again. Glowplug light never comes on but car still starts, alternator warning light didnt come on when the alternator failed...i think the faulty bulb is the only useful one that works. It's annoying as I used to be in the camp of investigate everything but now I wouldn't stop to check any gauge/light if it came on and would just assume it's another false alarm...
Have a look here on how to test the sensor: http://www.w124performance.com/service/w124CD1/Program/Engine/602_603/18-220.pdf

There's mention of fuse 8A, but that's probably for the whole instrument cluster. I would just replace the sensor and be done with the annoyance.
 

LostKiwi

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Or pull the bulb and go back to the old fashioned daily dipstick check....
 


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