Water Temp Light

Started the car for the journey home and after a few seconds the little red light came on and started flashing. I checked the water level and yes it was low, I topped it up but it hasn't stopped flashing.

Now home I've checked the level again and allowed the car to cool and warmed it up again. There's plenty of fluid in there but the light refuses to go out. It's not overheating and the fans cutting in just dandy.

What do you guys think? Is it just another faulty sender, I changed it a little over a year ago so surely it would last longer than this?

Tian

was looking for a link like this.. i find after i have been out for half hour, my red light flickers too... ??? water seems fine..

daz1971 said

was looking for a link like this.. i find after i have been out for half hour, my red light flickers too… ??? water seems fine..

and mine..
Not all the time tho, sometimes it goes off, then comes back on, last tiem it did it, i topped up the water again then just drove till it went out, after about 10 mins it did go out…

daz1971 said

was looking for a link like this.. i find after i have been out for half hour, my red light flickers too… ??? water seems fine..

Mines the same, flashes most of the time. The cure is black insulation tape, about 3/4 inch long stuck at the top, over the light. Out of sight, out of mind. Appears to be a fault in unit not an actual fault with the engine, sender etc.

Mine has been coming on at startup & staying on for anywhere between 5 & 20 mins…

I'm sure I read somewhere that if the coolant mixture is wrong then this make the light go on, something to do with the resistance…….

or did I just dream it… :scratch:

Eck said

Mine has been coming on at startup & staying on for anywhere between 5 & 20 mins…

I'm sure I read somewhere that if the coolant mixture is wrong then this make the light go on, something to do with the resistance…….

or did I just dream it… :scratch:

This is true and thanks for the replys lads but I really wanted an answer!!!

Tian :roll:  :mrgreen:

Tian said

Eck said

This is true and thanks for the replys lads but I really wanted an answer!!!

Tian :roll:  :mrgreen:

I think we're all looking for the answer mate…

Probably no one knows

dead or dieing sensor. check the one on the thermo-valve to the right of the block. it may even be a dodgy or dirty connection and again check this sensor first.

other than that check the others including the one of the expansion tank if yours has it.

novocaine said

dead or dieing sensor. check the one on the thermo-valve to the right of the block.

Can you describe what it looks like as I'm a 'block head'.

novocaine said

other than that check the others including the one of the expansion tank if yours has it.

I replaced this with a new one about a year or so ago so it should be fine, I also flushed the system in October so the mixture's right and clean.

I still don't get how the system could have lost so much water apparently overnight, the expansion tank was empty!

To Lawsy and all you others, if I have any joy I'll pass it on.

Tian :wink:

I replaced both sensors, cleaned terminals, etc. at the advice of my local specialist, really knows his stuff. Light still there flashing away all the time so was advised to use tape to cover light as the problem is at the back of clocks, expensive to change and as there is no actual 'problem' with engine why bother!

have you got wet carpets?
or you have a leak under pressure.(it may be after the thermostat so you don't see it till engine is warm. or it is only under high pressure so you dont see it till high revs.

you said the light kept flashing after you topped it up so it might be a cooked sensor from over heating? (not sure about this though)

novocaine said

have you got wet carpets?

Never had a wet carpet problem, I cleaned the carpets last weekend and they were bone dry.

novocaine said

or you have a leak under pressure.(it may be after the thermostat so you don't see it till engine is warm. or it is only under high pressure so you dont see it till high revs.

I've got a replacement expansion tank from ECP and I think the cap isn't a very good fit but good enough to keep it under pressure.

novocaine said

you said the light kept flashing after you topped it up so it might be a cooked sensor from over heating? (not sure about this though)

I don't think it actually overheated TBH. I stopped to fill it up before it got too hot. The oil and water temps were fine.

First thing I'll do is fit a new sensor, they don't cost much and it fixed the issue last time it happened.

Thing is I don't like driving around with it flashing as you just can't be too careful and one day soon it might flash for a reason and I'll end up ignoring it until it's too late.

Tian :roll:

Tian said

This is true and thanks for the replys lads but I really wanted an answer!!!

Tian :roll:  :mrgreen:

That light is the 'coolant too hot ' warning lamp . Comes on for a few seconds when you turn the ignition on ? Only flashes when engine warm ?

The coolant tank has a sensor in it , this is wired back to this empty relay [on picture next to fuze ] Both my Mk1 GTi's have this empty relay.


Listed on later models as 'Coolant low level indicator' .

So if your light flashes for no reason and you DO NOT have that relay fitted then the fault lies with the temp guage control unit as the 'coolant too hot warning lamp' is connected to this .

And that is bad new as it lies in the instrument panel .

To test the theory , connect both those wires together in the coolant tank , does the light come on ? No ? Thats because it does not go any where except to that blank relay .

  





 

Thanks chudd mate, I see what you're saying but it can't be this as it's been working fine now for over a year!!!

Anyway I went to ECPs and bought a new sensor, climbed back into the car, turned it on and would you believe it the ruddy light hasn't come on since!

One thing though the water level is dropping noticeably, could a badly fitting expansion tank cap be responsible by letting out water vapour?


Tian

I always worry about the loss of water [head gasket etc]. Holt's [trade name] make a sealant for cooling systems , swear by it chuck a bottle in as per the instructions with your anti freeze .  

I am interested does your car have this relay ?  Does any one else with a GTi have this relay fitted ?

 :dontknow:

chudd said

I always worry about the loss of water [head gasket etc]. Holt's [trade name] make a sealant for cooling systems , swear by it chuck a bottle in as per the instructions with your anti freeze .  

Okay probably best to be on the safe side.

chudd said

I am interested does your car have this relay ?  Does any one else with a GTi have this relay fitted ?
 :dontknow:

I'll have a look and get back to you.

Tian

at a guess id say its somthing to do with the level sensor or wiring maybe a bad earth

mine does the same and the only origianl sensor i have is the level sensor
all my other sensors go through the megasquirt and are 18T ones

I have just taken a temp guage to bits and the lamp is directly connected to this . So if there is no relay above slot 6 the guage is faulty .