Red temp light and reading off the scale

[oddnumber]

Afternoon chaps, got a slight niggle with my 1983 1.9 water cooled.

The coolant light has taken to flashing at the same time as the temperature needle goes off the scale. Rather unnerved by this I pulled over, checked coolant etc and all was in order. Engine not too hot either. Pullled off again and the same thing happened - so I checked, again all ok.

Drove it five miles home with the light flashing and the needle unnervingly off the scale. It drove perfectly. Would a fault in the coolant level sensor cause the needle to rise too? What else might cause these symptoms?

Thanks for any help

E D I T: just disconnected the coolant sensor at the back and sure enough the gauge went up and the light flashed. So would I be right in thinking that it points to a dodgy sensor?

[jrt]

I had the same problem after fitting a new sensor, the rubber bit where it plugs in stopped it connecting properly and it used to randomly pop off.
Try cleaning the prongs on the sensor, they can get furred up.
David

[oddnumber]

Thanks David. Did your light flash in addition to the needle rising?

It's bloody unnerving at first

[jrt]

Thanks David. Did your light flash in addition to the needle rising?

It's bloody unnerving at first

Yes, flashing light and needle off the scale
David

[jrt]

This may be helpful https://club8090.co.uk/forum/viewtopic.p ... t#p8132782" onclick="window.open(this.href);return false;
David

[shepster]

I had the same, it was a poor connection on the bottle sensor.

[oddnumber]

Interesting, thanks chaps. Just as per that thread linked, my needle shoots northwards too.

The connections look ok, so I'll get another sender and go from there. Glad it's not a genuine overheating problem.

[marlinowner]

If you pull the relay 43 that will kill the error if it's caused by the coolant level sensor. If the problem is still there then it's probably a short circuit on the wire to the coolant temperature sender. If pulling the relay stops the light flashing, as well as the sensor itself it could be a bad connection somewhere in the wiring - once the fault is triggered it stays until ignition is turned off. Worth changing the relay to a 42, then a coolant level fault flashes the light without affecting the gauge level.

[oddnumber]

Thanks dude, where can the relay be found in an early wasserboxer? Fuse box?

The problem stopped/started intermittently when I took it for a run earlier, which made me think a connection/sensor problem.

E D I T: just looked above fuse box, and no 42 or 43 relays

[marlinowner]

Hmm don't know where it is on early vans, would have thought near fuse box but someone will no doubt enlighten us.

[oddnumber]

Hmmm ... checked levels this morning and the header tank took half a litre to brim it again

[Mocki]

The flashing red led has three reason to flash
1. On its own, temp gauge cold or normal , it's telling you low coolant
2. With the temp gauge up at the hot end, it's telling you over temperature warning
3 randomly , it telling you that you have a wiring issue !

So, if the gauge is at the hot end and its flashing ( as per your description) it suggests it is the temperature gauge sender that is at fault, or the wire from it to the gauge.
Early water system has a single pole to chassis earth temp sender in the thermostat housing , next to the water pump, a single exposed spade terminal. Unplug it and see if the gauge (and light) behave
If it does stop it, the temp sender is at fault
If no change, check the wire visually for damage and earthing out , and trace it back

It's almost definitely not the coolant level sender that is causing this

[marlinowner]

early 43s send the gauge to max when low coolant warning is triggered.

[oddnumber]

Indeed - that's whats making me think (and hope ) that its a coolant level sensor problem.

A new sensor arrived today so we'll see what happens.

Thanks chaps.

[Ant-t]

I had a similar issue a while back, have you checked the feed from your expansion tank (behind the number plate) to the header tank? If that is failing the header tank won't be topped up when starting from cold and cause the temp gauge to go to max and the light to flash.