e270 diesel coolant level warning

[Al Smith]

Hello.... have had the coolant level warning symbol coming on for a few days,so replaced the sensor. Unfortunately the easy remedy has not worked
The warning is displayed only as the coolant temperature reaches normal , no sign when cold.
Having given a short run to get to normal temp and with the warning then displaying, I released the filler cap carefully and the level was up to the very top......left the cap off for 5 mins and it went back to near correct level and no warning light displayed. Within a minute of restarting the engine, the warning is back up.
Apologies for the lengthy explanation, but does anyone out there have suggestions as to where my next checks should be, the fan is operating correctly as is the aircon and heaters.
Any thoughts would be appreciated. Alan Smith

 

[JoeHorner]

If it's the same set-up as the C270 then, iirc, the coolant and screen wash level sensors are interconnected in some weird way. So a faulty screen wash sensor can trigger low coolant level (and the other way).

Not sure how temperature would be a factor though.

 

[alexanderfoti]

If "coolant, visit workshop" Issue is with the FAN on the radiator.
If "coolant check level" a sanity check of the sensor needs to be done.

As it comes on when it gets to temp, probably that!

 

[Al Smith]

If it's the same set-up as the C270 then, iirc, the coolant and screen wash level sensors are interconnected in some weird way. So a faulty screen wash sensor can trigger low coolant level (and the other way).

Not sure how temperature would be a factor though.

Thankyou Joe for your reply. Having looked at the access to the washer bottle sensor, have decided to take the action suggested by Alexander Foti and make sure that the new sensor is not faulty. Thankyou and I will update when I have got the answer......hopefully before 2024!!
Regards
Alan

 

[Al Smith]

If "coolant, visit workshop" Issue is with the FAN on the radiator.
If "coolant check level" a sanity check of the sensor needs to be done.

As it comes on when it gets to temp, probably that!

Thanks Alexander.....as explained to JoeHorner.....will be checking the new sensor before any other options and will update with results. Many thanks for your suggestion.
Regards
Alan

 

[JoeHorner]

Having looked at the access to the washer bottle sensor, have decided to take the action suggested by Alexander Foti...

Yes, it's not nice for access!

I discovered it the other way round - a faulty coolant level sensor was triggering a "screenwash low" warning. Which I only found was possible after struggling with the washer level sensor!

 

[Al Smith]

Update on latest position.
Installed new Merc genuine part in coolant level sensor.....no difference.
Thoroughly flushed coolant system and refilled with Merc antifreeze 50:50 with distilled water.....no difference.
Thinks.....will have to go to Joe Horners ideas, knowing that the washer reservoir, pumps, sensors etc are behind the ns front wheel arch cover....awkward.
Thinks....before doing all that I'll pump out the resrvoir with the 3 sets of jets to see if the low water sign comes up and NO it did not, so thinking again, I deduce the sensor in the washer rervoir may be dodgy.
Not wanting to spend further money needlessly, thinks....I'll try to take out the sensor to see if there's anythging obviously wrong.
2 hours later have succeeded in gaining access to the sensor but only by removing the complete reservoir and associated cables and tubes,looked ok put it back in position ,filled rervoir and guess what.....no difference.
Conclusion ....Spend money on a genuine Merc washer bottle sensor and try this idea that Joe put me on to.
Good job I'm retired....my labour costs me nothing and you do learn by trial and error with good advice. Watch this space for the next update on this exciting saga.
NB ...removing the reservoir without guidance is nearly as taxing as replacing the tailgate struts .....but youtube helped with that one!!!
'appy new year!