Water Gauge not working
 

Didnt know where to post this as it might be electrical it might not!

My Water Temp gauge is causing me some issues. When I first got the car a few months ago it did sort of work 80% of the time but it bounced around a bit from cold before settling and sometimes would sit at zero for a while before coming back in to life. Then it changed to flicking up to 3/4 straight away from cold start, then drops to half for a few minutes of driving (when the engine clearly isnt anywhere near that warm yet) before falling to zero where it stays. I think the general pattern is that when its hot it does nothing at all, when its stone cold it reads but not correctly.

I changed the sender which didnt sort it. I was then told that a common fault is that the pins on the back of the gauge corrode and the gauge doesnt pick up the signal. So again I've tried this, had all the clocks out last night, sanded the nuts and the washers down that attach to the back of the clock, sanded the base plate connections down,put it all back on, still no joy, tried diffident configurations of putting two washers on the back, no washers, two nuts, again no luck and nothing has changed.

Any idea's what this problem could be? I am thinking that I might just buy a whole new gauge cluster because the digital clock and the mileage counter is not working on the current one anyway. I had a look on ebay however and I am not sure what sort of variation there was in the clusters, by eye they look the same but are the points on the back all the same. Would a V6 Coupe Cluster (for example) fit my B3 2.3 Coupe?

I would think the V6 dash will differ in the rev counter electronics-having one too many cylinders.....and the red line will be lower!
Would expect the rest to be the same?....or at least a lot of it.
But don't quote me. Worth a shot if a cluster is cheep enough?

what state were the pins in the wiring plug into the sender ?

If they've gone green with corrosion, you'll need to either clean them up or replace

I am no expert on your model, but on my A4 there were two coolant temp senders.
One on the head to talk to the ecu for stat and enrichment duties and the second on the bottom hose rad outlet to talk to the gauge and fan controls, maybe a similar set up.

Ok so the sender I changed was coming off the Head. There is a switch at the bottom off the rad which I didnt change because I was told this operates the fan only? The terminals on the one I changed seemed to be fine.

That's correct. Only the mfts on the head controls the gauge.

Blue / brown wire is the one of interest( pin 1 on your connector for the sender) . Goes to the yellow connector pin 2 for the instruments

Mike please dont ever leave this forum- I couldnt run the car without you! Shame your not local as I would get you to go through and service the whole car!

I will have a good a prod round this evening. So the one on the bottom of the radiator is not worth touching at all by the sounds of it?

As I said , this was a 1.8t A4 2001 car, so maybe not similar, good luck tracing mate

Thanks chaps. So made some head way tonight but not solved as such. Took the brown plastic electric plug off the sender and checked the terminals inside the plug. Was only working from above the engine so couldn't see inside one half of the plug but scrapped the terminals with a screwdriver and flushed it out with electric cleaner. Cleaned the lume end of the plug but the terminals looked fine. The water gauge stayed reading all the way home, didn't just sit at zero like it normally does. From stone cold if you turn the ignition on the gauge slowly creeps up to 3/4 and tonight it stayed there all the way home apart from when I stopped at traffic lights where it dropped to zero and sat there for a few miles before going back up to 3/4. Certainly tampering with that plug changed something!

Is that a Meyle sender you've got in there for it to read 3/4 ?