AE101 water temp gauge

[spoonza6]

92 Corolla Levin ST 20v AE101 Manual

Ok

That's the car and recently I noticed the water temp gauge started reading lower than normal, then it started reading under low, then decided to bounce around on the odd rev up and now....nothing at all.

Doesn't move, even after car has been running 30mins.
Far as I can tell its not over heating...but that's just an eyeball diagnosis

Have noticed that it was slightly ticking which has now developed into a knock.
Engine runs as per usual, not straining or that. Smooth I might say.

Where do I start?

[Dell'Orto]

Temp sender for a start, it might have given up the ghost or the wire may be broken.

[Grrrrrrr!]

+1, dodgy connection somewhere, check the lead from the sender all the way back to the dash.

[Crucible]

Might sound silly but have you actually checked the coolant level in the radiator?

[92mr2paddy]

ive overheated a car before and it started ticking,, then knocking,, no fluid in radiator at all, def check that out first then wire connections

[AE82 FXGT]

Might sound silly but have you actually checked the coolant level in the radiator?

Start here.
If there is no coolant the temp gauge can't see the temp.... does your heater work? If the answer is no, check your coolant level!

[Crucible]

Low coolant will cause all the above symptoms. Fluctuating or no temp and hi rpm will be because there is no coolant passing temp sender and fast idle.

Pinking and knocking...well thats generally what happens when its overheating.

[Crucible]

Start here.
If there is no coolant the temp gauge can't see the temp.... does your heater work? If the answer is no, check your coolant level!

Bet me to it

[spoonza6]

Have just re attached a plug that came off on the thermostat housing, also pressed in any other plug I could see.

Coolant level is full. (Thought so but checked to be sure)

Could the water pump have died?

[Crucible]

So the wire you found off made no differance?

No wont be a leaking pump if the coolant level is ok. Also if the impeller is damaged or erroded it will generally boil over and cook a few minutes after start up.

It may well be a faulty sender/wire/gauge. You can disconnect at sender and ground the wire, the gauge should go up, that will eliminate gauge and wire.

For the sake of a few bucks maybe replace sender.

[andyztouring]

I would be looking at changing thermostat

[jacobrjett]

I would be looking at changing thermostat

please forgive me if im mistaken (this is a forum to learn off after all)

but doesnt the thermostat just check the temperature and send a signal to the radiator fan to start going? if the radiator fan was constantly on i dont think it would be enough to prevent the engine from heating up at all.

if i was wondering if the engine wasnt warming up, id run the engine for a bit and see if the radiator cap gets hot. if not, open it up and put your finger in the coolant and see if its hot. if its nice and hot... i would assume a sender fault.

im pretty sure the sender is a ground triggered signal, at least it will be on the oil pressure sender - disconnect sender (pain in the ass, you will have to remove the intake plenum to reach it) and then ground the wire. if the temperature gauge shoots up, the wire is fine... well, this is how id diagnose the wire on the oil pressure sender, not sure if the water temperature will be the same because its not a on/off signal, but hey, thats my input...

[Dell'Orto]

No, a thermostat is basically just a restrictor to stop coolant flowing fully when the system is cold, it doesn't send any signals. Most cars will have a fan switch somewhere in the system to tell the cooling fans when to switch on and off

[jacobrjett]

ooh thanks

[Crucible]

Generally the gauge would still register if the thermostat was stuck open. It wouldnt read much but it would still move. Reading his first post its not registering at all now.

Mind you it doesnt take much to check and elimanate it from the equation.

[allencr]

Could the water pump have died?

Yes it could have, but it would have to be after any of the symptoms that you've described, none of them related to anything like a coolant leak or the extremely rare coolant flow problem.