False 'Coolant level low' warning?

[PaulMdx]

Over recent months I've been getting the coolant level low warning light coming on intermittently. I have checked the radiator on a number of occasions and the level looks fine (i.e. full).

At first I thought it was when the engine was increasing in temperature (getting up towards 95C), however over the last couple of weeks it's started happening nearer to the usual 85C running temperature.

Other than hooking it up to the computer, any ideas?

 

[Blakey]

Have a look here...

http://forums.mercedesclub.org.uk/showthread.php?t=47890&highlight=coolant+level+switch

...should give you some clues.

Best of luck,

Chris.

 

[moosehead]

These can be a bit sensitive on level so you might need to top it up a little bit. I did have to replace the sensor on ours. If you look at the header tank the sensor is an insert that screws in from underneath i.e. unplug connector and simply twist sensor to remove (you don't have to drain system). If you have sausage fingers you might struggle. From memory the sensor was £7-8 from ECP.

 

[dickchailey]

My money is on the washer bottle sensor going open circuit (wired in series)

 

[moosehead]

I would check the header tank sensor first as the washer bottle is a b****r to get to, i.e. jack up front O/S, remove road wheel, remove inner arch and remove washer bottle. Refitting is tricky with the pipes, cables, etc. I've had 2 washer pumps fail over 10 years and it's not a job I enjoy!

I will check the warning lights on the dash when the wife gets home as I am sure there are separate lights for coolant and washers.

 

[bigasotonuk]

Hi,
There are seaparate lights for the washers and coolant tank but if either level switch goes U/S it can put the others light on.
I was sceptical of this when my coolant light would,nt extinguish, so regardless what i was told i replaced the coolant switch, the light was still on, took the the previously given advice washer bottle switch replaced, and low and behold coolant light out.
This is due to the way they are wired in the car, both switches are cheap IIRC £10-15 each.

 

[moosehead]

I'd still be inclined to check the coolant one first as it's a 5 minute job vs 1 hour+ if you are lucky on the 170.

 

[PaulMdx]

Thanks everyone for your responses. I wasn't expecting such a mass of replies! I will look into them accordingly and let you know how I get on.

Thanks again!

 

[PaulMdx]

I have now replaced the coolant sensor, but unfortunately the problem persists.

Interestingly after posting here, and prior to replacing the coolant sensor, the washer bottle was genuinely low, and the washer / coolant warning lights were on and off like a Christmas tree!

I am now looking at replacing the one for the washer. I'll reply with the results.

 

[PaulMdx]

Now replaced the washer bottle sensor, still persists. :-(

My father (retired mechanic) suggested draining/rinsing the radiator system. Any thoughts on the value of this and/or if there's any alternatives?

 

[Uncle Benz]

This warning light can also be telling you that the electric cooling fan is not working.

 

[PaulMdx]

Thanks. I believe the fans are turning as intended, but I will definitely check.

 

[nickid]

hi all I am new to this forum.
just picked up a LIMITED EDITION 2002 MERCEDES C 230 KOMPRESSOR SPORT WITH 2 TONE LEATHER and after driving home it came up on the dash that I was to check coolant and washer level but both are full. shock it happends after test drive.

 

[nickid]

is this the problem you are all taking about? and do I need to change the sensor on the washer bottle

 

[nickid]

collant level sensor

just go my me sensor from Mercedes and its different to the original


original

new

before I fit it, was my original upgraded and that why I have this one?

 

[Mauijoe]

Sounds weird but look under the car battery and see if a wiring harness is being pinched under the battery, happened to me and fixed it. Solved other problems with headlights and marker light. Also noticed a pair of thick red wires on the fender side in the same spot had some badly damaged insulation and tape that up with some electrical tape.

 

[mbogohse]

Merc - 450 Gl, CDI - False message to top-up coolant

I have a message that wont go away, even though the coolant was not low but I added some to the bottle just in case, I was in a hurry and didn't think much of it at the time.

Its no different, I make it go away and the message comes up again shortly.

Reading through this forum, I understand, I should replace the Water bottle sensor and not the Coolant sensor first.

Is that correct?.

I would really appreciate some feed back, even though this feed is a bit old. The message is so annoying and blocks all other info.

Does anyone have a picture of where they might be found exactly and how to replace.

Thank you

 

[PSDCampervan]

Mine came up recently with IC message 'Coolant low - visit workshop' that went away with a 15A fuse replacement in engine bay ECU fuse box. The blown fuse set several codes related to EGR & cooling suction fan as well but only that 1 message appeared in IC to indicate anything was wrong.

 

[Parkgate]

My CLK used to do it (coolant level low), but would go out with approx a cup of water added into the header every now and then (my driveway is on a slight slope so I think that added to the problem).
Anyway when I was replacing the rear brake lines over Christmas I also changed the coolant at the same time. I drained and flushed the system through a couple of times (until the water ran out clean at the rad drain, and running the engine for a few minutes before each flush, with the heaters on hot) topped up with a 50/50 mix and its not come up with a low coolant level warning since.
Maybe the crud inside the rad was absorbing a little of the water in the system? Whatever, a coolant change seems to of cured that annoying message.

 

[trickys320]

Hi, I have recently had a couple of coolant leaks, the pipe going through the firewall (replaced) and then the radiator (replaced) but my Check Coolant Level warning keeps coming on after 20 seconds or so. I have taken out the sensor today from underneath the coolant expansion tank and with the sensor disconnected from the harness I get a reading of 100 ohms. I didn't at the time realise it is a magnetic switch so will test again using a magnet to see if resistance changes to less than 5 ohms.

So with the leaks I had the expansion tank was running low for an hour at a time so is it possible for the float to have got stuck in the lower position?

I have tried looking through the cap hole to see it but my eyes wont bend round the corner!

Anyone have any methods of getting to the float please without taking the whole bottle off to see if it is moving please?

Thank you.