Coolant Temperature Light - Saxperience

4rivers · 22nd February 2018, 14:29

Ok - I have a 2001 Citroen Saxo 1.5 D (LHD) , and I have a problem with the Coolant Temperature Light .
Yesterday - I took it for it's annual inspection, technical control (mot) , and before going there, about 15 miles ( 20 kms) from where I live, I power washed it, including the engine and gearbox and as much as the underneath of the car as, I could reach.My vehicle has a bit of an oil leak, and the inspection guys, tend to frown on that. (Past experience) After queuing for 1.5 hrs , did the inspection , no problems - but when I drove it out , and started my journey home I noticed the Coolant Temperature Light was on - so I immediately pulled over - popped the lid, checked for any leakage, from hoses etc , and underneath the vehicle . There was none . Then I checked the header tank , for fluid level, as it was basically a cold engine , there was little risk of getting burned, and although the coolant was quite warm , there was no fluid loss. So I drove home with the light on - presuming it was not a serious problem, and the alternative was leaving the car, and walking. Turned the air blower on , hot air . But the fan for the radiator did not come on . In fact I never ever remember the fan ever kicking in . I don't do big journeys - 36 miles (50 kms) is about my limit. The light went off right at the end of my journey . This morning I checked the fluid level before starting , and it was ok, when turning the ignition on , the Coolant Temperature Light didn't come on , all the other indicator lights did, oil, handbrake,heater coil etc Started ok ,no problem , traveled about 3 miles (5kms) stopped went to the supermarket , came out , started the car again and the Coolant Temperature Light started flickering red, and then full red , drove home , the air blower was hot air, but the radiator fan never started . Since then , I have checked the oil , to see if there is any coolant contamination , which I think would indicate , a blown head gasket . There was no coolant contamination with the oil .

I have checked this site - for a similar problem , and not found anything the same - google hasn't helped either .

Could someone please make a suggestion , as to what they think the problem is , and the remedy . I don't have a Haynes manual. So I would need simple explicit instructions .

MartinObviously · 22nd February 2018, 18:45

Head gasket failures on a 1.5d are quite rare being a copper or MLS gasket as standard.

There is a small chance the blue temp sensor on the cylinder head is faulty or perhaps some air is stuck underneath the sensor somehow. They're really cheap to replace so I'd start with that.

When the light comes on, check the actual coolant temperature with a thermometer into the header tank, of course be careful with the pressure!

I think the light comes on at about 105 degrees c I think. If it's less then I would say the sensor is faulty.

This method works well because the header tank gets filled by coolant coming straight from the head.

the best method would be to use a 2 dot laser thermometer and aim it right at the base of the sensor and get a temperature reading. these are really accurate.

On a 2001 model, the fan on the radiator is controlled by a switch on the radiator itself.

For example a partially stuck thermostat may allow the coolant temp light to come on, but by the time the water reaches the radiator it is not hot enough to trigger the fan switch.

Don't worry about the light not coming on when you first turn the key, your 2001 has a digital dash, the coolant warning light never comes on with the ignition as it does in older models, this is because it is LED and doesn't need to perform a "bulb" test for the coolant warning lamp.

4rivers · 23rd February 2018, 11:06

Many thanks , for your informative reply '' MartinObviously'' I will order a Blue Temp. Sensor - here (Belgium) I found the Citroen dealers to be very unhelpful, concerning spare parts for my saxo - the last one, advised me to check out the scrap yard, when I wanted some hinge pins . I got them from ebay. But currently use Mr Auto for almost everything else.

A 2 dot laser thermometer,is out of my league, I am afraid , it will be hard enough finding a regular thermometer.

I note that next to the blue sensor is a green sensor , would it be worth ordering that at the same time , does it have a different function ?

If it is not the Blue sensor - how would I find out if it is the thermostat,you noted that a partially closed thermostat could cause the Coolant Temperature Light to come on . Is it difficult to replace ?

One last question - as I don't have the owners manual , how often should the coolant be changed /replaced ?

stevo67 · 24th February 2018, 13:36

You power washed the engine,there is the clue.You have moisture in the electrics.

MartinObviously · 24th February 2018, 23:20

Quote:

Originally Posted by 4rivers

Many thanks , for your informative reply '' MartinObviously'' I will order a Blue Temp. Sensor - here (Belgium) I found the Citroen dealers to be very unhelpful, concerning spare parts for my saxo - the last one, advised me to check out the scrap yard, when I wanted some hinge pins . I got them from ebay. But currently use Mr Auto for almost everything else.

A 2 dot laser thermometer,is out of my league, I am afraid , it will be hard enough finding a regular thermometer.

I note that next to the blue sensor is a green sensor , would it be worth ordering that at the same time , does it have a different function ?

If it is not the Blue sensor - how would I find out if it is the thermostat,you noted that a partially closed thermostat could cause the Coolant Temperature Light to come on . Is it difficult to replace ?

One last question - as I don't have the owners manual , how often should the coolant be changed /replaced ?

I would change the coolant every 5 years.

A thermostat is about 5 euros, the top radiator hose where it goes into the cylinder head is 3 really long 10mm bolts. you simply remove those bolts and lift the pipe off and change the thermostat. You could simply just change it and see if that makes a difference.

The green sensor is for the ECU, it only really influences the electronic timing advance and the time for the glow plug relay. Don't change that if you have no symptoms of faulty glow plugs or misfiring etc.

You can get laser thermometers on Ebay for about 20 euros! Personally I find these engines rarely overheat, I drove one with no cooling fan for 3 years and the light came on once in the summer when I was stuck in traffic.

Quote:

Originally Posted by stevo67

You power washed the engine,there is the clue.You have moisture in the electrics.

This is a possibility, after all it's only water resistant for weather. I never noticed that in the original post!

Mine is fine though

it's been steamed many times.