Mk 1 Temparature Gauge Reading Too High?

[Lovejoy]

Hey everyone,

I'm not really much good with cars, so I'm looking for some advice, please!

 

Driving last night I saw the temp gauge was almost in the red, so I assumed there was a cooling problem. But the coolant tank is full, and there's no water in the oil; I haven't checked the pump yet, so I don't know if that's OK or not.

 

But when I switched on the ignition this morning, the gauge was pointing at the 'N' of 'NORM', already about a quarter of the way across, instead of cold. So I'm wondering, is this a sensor problem or something?

 

Any ideas?

 

 

[gregers]

thermostat stuck maybe?

you certainly dont want to be driving it like that for too long.

ive had this in the past,and what i have done was to turn the heater on full this helps to take

the heat out of the engine,but its purely an emergency exercise.

[BrianH]

Hey everyone,

I'm not really much good with cars, so I'm looking for some advice, please!

 

Driving last night I saw the temp gauge was almost in the red, so I assumed there was a cooling problem. But the coolant tank is full, and there's no water in the oil; I haven't checked the pump yet, so I don't know if that's OK or not.

 

But when I switched on the ignition this morning, the gauge was pointing at the 'N' of 'NORM', already about a quarter of the way across, instead of cold. So I'm wondering, is this a sensor problem or something?

 

Any ideas?

That sounds like the sensor for the gauge to me, though wiring is possible given the car was cold when reading normal.

 

When mine failed it started reading hot then would alternate all over the place on the gauge. You don't say which engine it is, the 2.0 is on the thermostat housing underneath if i remember correctly (theres another sensor on there which tells the ecu the temperature as well, easiest way to tell which is which is to unplug one and see if it makes the gauge drop down),

 

its a case of obtain a new sensor, unscrew the old one and replace it and plug it back in. not particularly difficult except for getting to it really (access is a bit awarkard), if it still plays up then the wiring could be at fault, it may be worth checking over the bits you can get to of it first (any obvious damage to the wires etc needs fixing before tacking the sensor)

[Lovejoy]

...what i have done was to turn the heater on full this helps to take the heat out of the engine,but its purely an emergency exercise.

Yeah, I did that on the way home - heating on full, all windows open! :)

 

That sounds like the sensor for the gauge to me, though wiring is possible given the car was cold when reading normal.

 

When mine failed it started reading hot then would alternate all over the place on the gauge. You don't say which engine it is, the 2.0 is on the thermostat housing underneath if i remember correctly (theres another sensor on there which tells the ecu the temperature as well, easiest way to tell which is which is to unplug one and see if it makes the gauge drop down),

 

its a case of obtain a new sensor, unscrew the old one and replace it and plug it back in. not particularly difficult except for getting to it really (access is a bit awarkard), if it still plays up then the wiring could be at fault, it may be worth checking over the bits you can get to of it first (any obvious damage to the wires etc needs fixing before tacking the sensor)

 

It's a 2.3; I'll see if I can find the sensor... my Haynes manual says the sensor's on the underside of the thermostat. I'll go and have a look.

 

Thanks! 

[Lovejoy]

So - the wiring looks OK to a visual check; nothing obviously worn or cut. I've disconnected the temperature gauge sender, and the needle stays at the cold point of the gauge with the ignition on. So it looks like that's the faulty part, and I've ordered one. 

 

I expect it'll be a bit of a pain to change; I guess you have to drain the system first? 

 

I think it'll be OK to drive in the meantime - the sender just controls the gauge, and there's a different sensor to supply temp info to the ECM. 

 

cheers

Michael

[BrianH]

So - the wiring looks OK to a visual check; nothing obviously worn or cut. I've disconnected the temperature gauge sender, and the needle stays at the cold point of the gauge with the ignition on. So it looks like that's the faulty part, and I've ordered one. 

 

I expect it'll be a bit of a pain to change; I guess you have to drain the system first? 

 

I think it'll be OK to drive in the meantime - the sender just controls the gauge, and there's a different sensor to supply temp info to the ECM. 

 

cheers

Michael

You've no idea how hot the engine is getting, so that call is upto you if you drive it or not. if you have any access to diagnostics showing live info (torque on a phone for example) you can monitor what the other sensor says.

Provided its not getting too hot it would be fine, but you won't have any real warning as to how hot its getting before steam starts appearing!

 

I wouldn't bother draining it unless its really necessary or the coolant is in poor condition - some coolant will come out on removing the sensor, but not too much. Topping back up afterwards should cure this, may be a good idea to allow it to come back up to temperature with the pressure cap removed to allow any trapped air to escape. Having some spare coolant of the right type (to match what you've got) not a bad idea.