Temperature Gauge Not Working

[iancc]

Hi,

I have searched the forum for this as i thought it would be a common problem but could not find anything relevant, so here goes.....

I have noticed on the last 2 (short - under 10 miles and sat in a bit of traffic) journeys that the temp gauge indicator is not moving on the dash. It just stays flat to the left (as it does with the ingition off). It has always worked fine uptil now and never had overheating problems. I check the coolant level quite regularly and there doesnt appear to be any leaks.

I took the van into a VW garage and they had to drop the engine to reattach the exhaust manifold and since then i am having this problem.

I have disconnected (that is almost as far as my technical experience takes me) the wiring plug from the top of the coolant level sensor and the connection between the wiring plug and the sensor is full of coolant. Is this normal or could this be a problem?

The temperature gauge sensor is in place. I have read that if I touch the 2 wires coming from the top of the temperature gauge sensor together, the gauge indicator should shoot up and therefore determine that the temp gauge sensor is faulty. Is this correct?

thanks.

[syncro up]

Ive just had a similar problem, gauge was slow to work, then stopped completed, just didnt move.

Theres two obvious things to look at first, there could be a bad terminal or break in the wire around the temp sensor. Check the wire continuity with a multimeter to a point further up the wire, or all the way to the dash.

Or the sender bust, as mine was. You apparently can test the sender by taking it out and measureing the resistance across it while in water which you warm to near boiling. There is a post on here and think its in the haynes manual which tells you what the resistances should be.

[CovKid]

Often its just the multiplug connector to dash.

[boatdog]

i didnt think the coolant level sensor had any thing to do with he temp gauge i think the temp sender (on mine anyway 1.9 dg) is down next to the themastat housing? maybe this was diconnected when your motor was disconected? i checked mine by pulling connector off temp sender and grounding it out temp gauge then goes to full hot position if all is working

[kevtherev]

Hi,


I have disconnected (that is almost as far as my technical experience takes me) the wiring plug from the top of the coolant level sensor and the connection between the wiring plug and the sensor is full of coolant. Is this normal or could this be a problem?

that's a problem

The temperature gauge sensor is in place. I have read that if I touch the 2 wires coming from the top of the temperature gauge sensor together, the gauge indicator should shoot up and therefore determine that the temp gauge sensor is faulty. Is this correct?

that is correct

I see it as your sensor is shagged... or you have a poor earth to the sensor

[iancc]

OK. I will try 'shorting' the temp gauge sensor wires first and see if its the sensor that is at fault.

Still a bit concerned about the coolant 'leaking' through the coolant level sensor. Could high pressure in the coolant system (due to the temp sensor not working) force coolant through the coolant level sensor?? Does the temperature sensor only send to the temperature gauge on the dash or does it control the coolant system too. Am i right in thinking the thermoswitch (separate to the temp sensor) controls the coolant system and the temp sensor/sender only controls the temp gauge? Sorry to ask so many questions but I just like to know and everyone here is so helpful!

Thanks again

[kevtherev]

No the coolant should not leak through...if it does then it's faulty...whether it works or not (there is an "O" ring that might fail if you have the plastic thermostat housing)

The temp sensor only works the gauge

The thermoswitch controls the manifold and carb heaters for cold starting.
The themoswitch is normally closed and opens at 85 deg C
It switches a relay (relay No 1) in your junction box in the engine bay
The relay then allows a lot of current to heat the manifold (under the carb) and to the carb heater (de icer) and finally the auto choke.

nothing controls the coolant except the thermostat and the radiator fan thermoswitch.... oh and the water pump