Low coolant warning light problem

[lofty]

Hi,

Had the cambelt and waterpump changed on my 2001 2.0 hdi 110bhp LX last week. The garage obviously drained all the coolant out and refilled with the correct antifreeze/water mix and bled it all properly.

Im getting the low coolant level light on the dash every morning now, but only for 30 -60 seconds, when ive driven up the street, the light goes off. The level is spot on in the header tank, the wiring connection to the level sensor is tight and dry, and other than this, the car is fine, ie heaters are hot, temp gauge works fine, fans work A1. Once the lights gone off, it stays off for the rest of the day.

I suspect the fault is with the sensor in the header tank, sticking or something. Can the sensors be extracted from the header tank and changed/cleaned etc etc, or will the stealers want to supply me a whole new tank assembly?

I appreciate i could possibly "live" with it, or even bodge the sensor wiring to take the light out permanetly, i just wondered if there was a straight forward solution?

Matt

[mjb]

First of all I'd suggest unplugging+plugging the sensor connector on top of the tank a few times, it could just be a bit of coolant/water has got in there and is causing a bad connection

[lofty]

First of all I'd suggest unplugging+plugging the sensor connector on top of the tank a few times, it could just be a bit of coolant/water has got in there and is causing a bad connection

Tried that already, cleaned the connector out with brake cleaner (was bone dry anyway), bit of WD40 and worked it on and off a few times.

Is the sensor on a type of float mechanism i wonder? I suspect that as the header tank was emptied, the "float" must have gone lower than ever before and picked some crap up on it?

More of an annoying fault TBH, but im a fussy bugger LOL.

[Welly]

When you say the level is 'spot on' - how do you know? we've all got our own definition of where the level should be....

Here's mine:

[lofty]

When you say the level is 'spot on' - how do you know? we've all got our own definition of where the level should be....

Here's mine:

Same as mine, if anything, mine might be slightly (but only just) higher, just enough to cover the outer ring area (if that makes sense)

[406silverhdi]

same happened to mine after the cambelt/pump change

i put a new sensor as pictured in, problem solved

think i have a spare around as i picked a couple up from the breakers

[lofty]

same happened to mine after the cambelt/pump change

i put a new sensor as pictured in, problem solved

think i have a spare around as i picked a couple up from the breakers

I think your right, i had a look this morning before work, had a twist of the sensor and it moved anti-clockwise quite easily so im gonna get it out dinnertime and have a fiddle under the hot tap with it, see if its full of crap or something.

Cheers for all the tips so far guys.

I'll be back! LOL

[lofty]

Update - went and had a fiddle in my lunch hour, disconnected the wiring plug off the top, turned the sensor 90 degrees anti clockwise and, bit of pursuasion it was free. Didnt get a photo of it but basically there are 2 x plastic covered probes with exposed metal ends about 50mm long and 10mm (or less) apart.

The metal ends were covered in a gunky furry substance which i can only assume was interfering with the electrical connection between the two. I gave them a good wipe off with some blue paper towel and refitted the sensor.

Started the car and hey presto, no warning light! (for now!! ) LOL

[Welly]

There's nothing more satisfying than a cheap fix like this. Well done fella

[steveleyland]

guys, any ideas my coolant light came on topped it up each day now for about a week light sometimes comes on or maybe not at all but serious amount of coolant seems to be disappearing.

Checked under bonnet even with engine hot cant see any leaks anywhere.

If i loosen bleed screw on radiator coolant is coming out, and also when i disconnected overflow from radiator to bottle return.

Heater works fine, temp gauge never gone over 90

???

[mjb]

Look for stains on the radiator, either white or coloured. If you see any, or often pull up behind cars and think their exhaust's smoking a bit, you'll be wanting a new rad

[steveleyland]

Ha, today it did overheat just as i got to work stop light came on and temp very high.

Got RAC to look at it said was a large airlock stopping water from circulating, lots of foam came out when bleeding system - not sure if that due to radiator sealant or egg whites lol.

He took off thermostat and said it fecked, made a temp repair to get me home. need new thermostat, is there a specific model no for 406 HDI diesel ?

Then did pressure test to 5 bar did not lose any pressure so no leak ?

[mjb]

Thermostat's just a few quid - make a note of your VIN number, phone the stealer, then pick it up in a few days after they've got it ordered in

Sounds like someone changed the coolant without bleeding it properly

[steveleyland]

local stealer had one on the shelf, changed it and just filled with water ran it 100 miles ok, then got 2 litres of antifreeze from stealer and replaced.

Not as green as the one in the pics though, what is it ?

have a thing about it being right colour, blue just isnt right, . . .thats for leds lol