Coolant light flashing..?

Have a problem with the coolant warning light flashing sporadically. This is the one, according to the book, that comes on if either the rear blower fan has failed or the coolant level is low. Coolant level checked several times over past few days and perfect. Fairly sure blower fan working too. However the light only comes on when 'pushing on' round the back roads. If I'm cruising up the motorway no problems at all. But some fast acceleration on an A-road soon sees the light on. No other indications. Any ideas?

You are possibly checking the level with the engine not running? It may look good stood still. Try going on a 5 minute drive then check with the engine running, I reckon you will find it has dropped as the hoses have swollen slightly or due to air in the system. I normally top mine up with the engine still running up to the level. When stood it does not climb, stays at same level.

Thanks Lloyd, I'll try this. Was merely going off the book and standard practice, of checking whilst cold. Surely if I top up whilst hot and running, when cold it will effectively be overfull?

Thats what I was trying to explain, I am quite confident on your car that all looks good with no engine vacuum (engine off) but after a few minutes of driving with engine still on check again and the level has dropped leaving the level-check sensor out in the dry putting the light on. You have nothing to lose, just top it up to level with the engine running after a run, I am confident it will sort it out & not rise any higher than the level with the engine off. PS Unfortunately this is usually the first signs on a leaky rad or expansion tank so get saving.

Also check the coolant tank cap. If the part number ends in "0" then ditch it and get the latest version.

Interesting.... Richard, you should write a list of these things, very useful.

Is there a fault with the coolant cap design then?

Yep, I would think so but still do the top-up I mentioned.

Coolant Light Flashing Hi Did'nt know there was a problem with the cap, but the expansion tank can be an issue. I have had mine replaced on my 02 C2 recently, never had a warning light issue though despite losing coolant. I used to check the level physically pre & post drive and always kept topped up. If its the expansion tank you get either a small puddle directly below the left exhaust, or if lesser leak can see some white residue on the top of the left exhaust. The replacement cost circa £150 at my north london indy so not a killer, still have original cap but may take advice so will check part number. Regards M :bye:

Coolant Light Flashing Hi Did'nt know there was a problem with the cap, but the expansion tank can be an issue. I have had mine replaced on my 02 C2 recently, never had a warning light issue though despite losing coolant. I used to check the level physically pre & post drive and always kept topped up. If its the expansion tank you get either a small puddle directly below the left exhaust, or if lesser leak can see some white residue on the top of the left exhaust. The replacement cost circa £150 at my north london indy so not a killer, still have original cap but may take advice so will check part number. Regards M :bye:

Coolant light flashing Hi there, I had a similar problem with my '03 C4S. The OBC flashed up "engine compartment blower failure" when in fact it was working. And the water temperature light flashed when the temperature needle was indicating 85 - 90 degrees , which to me, appeared to be within normal limits. The garage checked the fluid levels, and the problem occurred after a good drive. They said it was faulty sensors, replaced them under warranty and the problem has not occurred since. I hope that helps. Cheungy

Cheungy, That sounds more like my problem. There's virtually no coolant level difference with the engine cold, or hot after a long run, aside from a couple of mm which I have topped off to be on the safe side. There's no white residue in the cap and no leaks or losses otherwise. Do you know where the sensor is that you had changed? I'd like to swap it to test if this is the problem.

Anyone with a similar problem - finally fixed this by getting the new cap as advised. Out of interest the part number on the original was version 0.0. On the replacement it was version 4 and a significant redesign inside, having a collar and flange to prevent coolant loss.

:sad: Nope, not fixed after all. Bl**dy light flashing again. New puddles or residue but guess I'll have to have the tank changed.

I had my tank out a couple of weeks ago, bit of a fight to get it out and back in as it's an awkward tight fit. I attempted a polypropylene tank putty repair and felt I'd done as good a mend as possible following instructions and tested up to temperature. Just got the car back on the road after waiting for new tyres and the tank leaked again after 20 minutes of spirited driving. LLoyd, I'm not sure if you'll be able to get a better weld done but I'm not exactly relishing the thought of putting this new tank in!! You've been warned!! :nooo: