Water warning light flashing

[Horza]

Hi, I wonder if anyone can help.

It's a diesel van 1987 vintage and the water light is flashy flashing. It started intermitant with faint flashing, full flashing and steady on. Now it's it's steady strong flashing (except when it isn't) after me wagling everything.

The temp guage seems to be behaving normally otherwise. Rises slowly to temp, stops when the thermostat starts opening, rises again and drops when the fans kick in. Messing with the cab heater produces variations in the gauge and the pipes are hot to touch but not overly so. The coolant bottle isn't "pumping it'self up" with gas/air. I swapped the water level sensor for a known good one from the other van to no effect either.

I'm tempted to say electrical fault but where? given that there is no water level warning light relay in position 3. Where is this function done in later vans? Is there another non electrical cause I can check out?

Any help and advice would be gratefully recieved.

Many thanks

Euan.

[E D I T]I have just read the wiki as instructed but am still slightly at a loss. I did try in the box in the engine bay and wiglled the multi plug till it fell off and had to be put back on. I may take the dash pod off later and give it a clean. Earth fault is now the prime suspect.[/E D I T]

[R0B]

have you checked the low water sensor.thats screwed into your expansion bottle.

[Horza]

Yea, swapped it for the one from the syncro, no change.

I wish I knew what it was supposed to be telling me i.e temp it comes on at, resistance of sensor, which sensors, etc.

[jed the spread]

Everytime i have a problem like this it seems to be the earthing crowns behind the fuse box. Give them a rub with a map of the desert see if it helps. Worth a try especially if you see green fury stuff round them.
jed

[R0B]

sorry mate.i should of read you post more thoroughly

I swapped the water level sensor for a known good one from the other van to no effect either

[T'Onion]

Hey up Ewan

I'd be going around all the earthing points on the van , and then all the other conectors
Check them for corrosion and clean and recrimp where needed.

[Horza]

Thanks guys, I'll get my scrubby out and start checking all the earths. It has just sat for 18 months without moving

[steve8090]

Ewan

One more thing to check, when the alternator starts to go it can overcharge the system with electricity, check the voltage at the battery with the engine running just to make sure it is in the region of 13.8v, if the alternator does overcharge I've seen these lights do all sorts of weird thing from being dim to alternating flashing, just eliminate it from your list, an easy one.

[jed the spread]

Thanks guys, I'll get my scrubby out and start checking all the earths. It has just sat for 18 months without moving

Bet you a pound its the earth crown like i said

jed

[Ian Hulley]

Hiya Euan

As has been said if you've swapped the sender itself (which crack and short out giving false readings) for a known good one, my money's on the common earth ... owt else acting the goon ?

Ian

[Horza]

Thanks folks. I have wiggled and scrubbed and reinsulated all over the shop and now the light has gone out. The splattergun approach means I have no idea what caused it in the first place. If it reoccurs I will check my alternator output first off (this would make perfect sense as the alternator light coming on in my van means my engine has fallen off) and I could stand having a good look at earths and things this weekend as they really don't like being stood still too long do they?.

This van has the best online tech support!!

[T'Onion]

good , now get the rest of it sorted and get out and use it .. its been for too long

[Mocki]

im always late!
if it happenes again, check and see if there is a pattern to it, because if , say, it happens when you use any other power(brake lights, headlights, heater fan, or the leccy pump in the engine bay comes on) it could be the engine/gearbox nose earth, was on mine, looked good, didnt affect the starter motorness, just when voltage dipped it set the warning light off, well on...off, on,off, on you know. a ariation of mr shaws suggestion i guess.

also check for moss in the fuse box...hahaha