Non working temperature gauge

[jswagger]

Ok, next instalment.

I couldn't get a resistance reading from the temp sender so replaced it with a new one. More coolant came out than I thought but the new one is in and the temp gauge still doesn't move! I resistance tested the new one before putting it in and it was around 1400 ohms cold. Also the gauge moves when you short out the sockets on the sender plug (something it didn't do before) so the wiring must be ok.

Only thing I can think of now is to try a new sender plug? I've tried cleaning it up and all the continuity tests done from it have worked but I will order a new one from Vehicle Wiring Products on Monday.

[AngeloEvs]

You are almost done but take it for a good run, at least 30 minutes with the heater off, this will warm the coolant quicker, the temp gauge can be slow to show movement especially in cool weather. Worth a check before thinking the conX is faulty.

[zanzibaa]

Yep I have been having the problem and today found the connextion plug from the sender was the problem. somehow the wires inside were almost through! (maybe 20 years of hot/cold/hot/cold?) kind of the last thing id check really and certainly would have been after replacing the sender itself.

Thanks to the diagram! Nice one!

[Grun]

I couldn't get a resistance reading from the temp sender so replaced it with a new one. More coolant came out than I thought but the new one is in and the temp gauge still doesn't move! I resistance tested the new one before putting it in and it was around 1400 ohms cold. Also the gauge moves when you short out the sockets on the sender plug (something it didn't do before) so the wiring must be ok.

Just wondered if perhaps you now have an airlock in the cooling system.....coolant out means air in. Nothing is easy on the T25 waterleaker.
Look at the wiki if bleeding is new to you.
Mike

[jswagger]

I couldn't get a resistance reading from the temp sender so replaced it with a new one. More coolant came out than I thought but the new one is in and the temp gauge still doesn't move! I resistance tested the new one before putting it in and it was around 1400 ohms cold. Also the gauge moves when you short out the sockets on the sender plug (something it didn't do before) so the wiring must be ok.

Just wondered if perhaps you now have an airlock in the cooling system.....coolant out means air in. Nothing is easy on the T25 waterleaker.
Look at the wiki if bleeding is new to you.
Mike

Bleeding is very new to me so really hope it won't come to that.

I'll take it for a long run tomorrow, fingers crossed......

[AngeloEvs]

You lost coolant and quite a bit if you didn't set the heater to cold , it needs bleeding otherwise you could end up with bigger problems than a non functioning temp gauge! - I hope you read this and the wiki before you take it for a long run. There are two methods for bleeding so read the wiki version and the 'Baxter' method (no ramps needed) described in a thread in this forum - do a search!

[jswagger]

You lost coolant and quite a bit if you didn't set the heater to cold , it needs bleeding otherwise you could end up with bigger problems than a non functioning temp gauge! - I hope you read this and the wiki before you take it for a long run. There are two methods for bleeding so read the wiki version and the 'Baxter' method (no ramps needed) described in a thread in this forum - do a search!

I'm afraid I can't remember if the heater was off, it def is now as I turned it off to try to get the engine warmed up when I toook it for a run yesterday.

Warning noted about not going for a long run, till I have sorted the bleeding. I was planning on doing a coolant change in the summer, might as well bring it forward. Look out for a new thread on the problems I have then

[jswagger]

Back again, next instalment

I have managed to get the temperature gauge operating although to compensate the clock has stopped working! Just one question how far over to the right should the gauge go in normal use? I have let the engine idle for 20 mins and the needle is well past the LED in the middle and I am nervous about letting the engine keep running as I don't want it to overheat.

If the system hasn't been bled properly can this make the gauge overread?

Thanks again,

[AngeloEvs]

LED usually sits around centre or slightly left under normal conditions but would probably go slightly right of the LED when idling. The cooling system needs bleeding having lost coolant while replacing the sender. The Rad fan should cut in eventually and the coolant LED begin to flash if you overheat but you need to ensure that there is no air in the system for the system to work correctly.

[atcompton]

this might seem obvious, but you are sure you have removed the socket from the right plug, I spent two years trying to get my temperature gauge working and I was constantly testing the wrong plug in the thermostat housing, it is the one you cannot access from the engine bay, not the one on the left hand side of the thermostat housing, that sensor is for the carb heaters relay.

Wong sensor replaced?
Looks like I made the same mistake
I replaced the sensor (blue with 2 flat pins) with a new one (identical except it had a black body), but it seems I replaced the carb temperature sensor instead of the gauge sensor.
I did test the old one by suspending it in a saucepan and heating it and the resistance changed as it got hotter - so I guess it was OK. Do the blue body and black body sensors have the same electrical values ?

[clartsonly]

no they dont, get a replacement blue one, I had to get one from euro car parts as GSF couldn't get one.. I think brickwerks sometimes stock them.

the blue one is a switch which simply switches a relay which allows high voltage to heat the inlet manifold (i think) a the black one.. although mine (and a replacement, both GSF ones) always reads 3/4 instead of half on the temperature gauge is a variable resistor.

btw if you ensure you leave the expansion tank cap on when quickly swapping these sensors over very little water escapes, make sure you either retrieve and replace the o ring or if it is still good only have one o ring in at a time.