Technical Flaky Temperature - Sensor Location '99 idtd

[HLA91]

Hi,

I've got a 1999 2.8idtd Motorhome, which has a temperamental temperature.
It's fine most of the time going up about a third of the way up the scale, but then will randomly drop completely below the minimum 50c line and then a few seconds later pop back to its previous level.

My question is, whereabouts is this sensor so I can see if I can replace it myself, I'm normally the kind of person who take their vehicle to the garage but this ancient thing has cost me quite a bit recently so trying to be a bit more DIY.

I've done a fair about of goggling but can nail down an answer, having looked around from above I couldn't see any wires going into the coolant pipes or radiator, so went underneath and found some wires going to a connector on the passenger side right on the bottom of the radiator. Is this the coolant temp sensor I need to rip out and replace? Ones I've come up online with Motorfactors have 2 pins but this connector had 3 wires so didn't want to go pulling things apart unless I was sure.

Most grateful for your help.

Thanks

 

[the green vanper]

Hello,

Looks to me like air in the cooling system, which may cause severe damage to the engine.

Bleed the system as soon as possible.

The temperature sensor of the cooling system is usually in the thermostat.

 

[Communicator]

Hi,

I've got a 1999 2.8idtd Motorhome, which has a temperamental temperature.
It's fine most of the time going up about a third of the way up the scale, but then will randomly drop completely below the minimum 50c line and then a few seconds later pop back to its previous level.

My question is, whereabouts is this sensor so I can see if I can replace it myself, I'm normally the kind of person who take their vehicle to the garage but this ancient thing has cost me quite a bit recently so trying to be a bit more DIY.

I've done a fair about of goggling but can nail down an answer, having looked around from above I couldn't see any wires going into the coolant pipes or radiator, so went underneath and found some wires going to a connector on the passenger side right on the bottom of the radiator. Is this the coolant temp sensor I need to rip out and replace? Ones I've come up online with Motorfactors have 2 pins but this connector had 3 wires so didn't want to go pulling things apart unless I was sure.

Most grateful for your help.

Thanks

The 2,8idTD is a Sofim 8140.43, while the 2.8jtd is a Sofim 8140.43s. As the 2.8jtd was developed from the 2.8idTD, I would expect the thermostat locations to be similar. The 2.8jtd has an extra sensor for the ECU which is used for fan control and injection timing.
On my 2.8jtd you can just glimpse the sensors when peering between the intercooler hoses towards the LHS of the vehicle. For access either remove the intercooler hose(s), or the air filter housing.

The linked photo was submitted of a 2,8jtd was submitted in a recent thread, and should serve to illustrate the location. See here,

Unfortunately there may be a further complication with the 2.8idTD, in that it has a voltage regulator to supply perhaps temperature and fuel gauges. I cannot be sure as I have never owned one.

Do take note of the warning given by @the green vanper in post #2 above.

 

[HLA91]

The 2,8idTD is a Sofim 8140.43, while the 2.8jtd is a Sofim 8140.43s. As the 2.8jtd was developed from the 2.8idTD, I would expect the thermostat locations to be similar. The 2.8jtd has an extra sensor for the ECU which is used for fan control and injection timing.
On my 2.8jtd you can just glimpse the sensors when peering between the intercooler hoses towards the LHS of the vehicle. For access either remove the intercooler hose(s), or the air filter housing.

The linked photo was submitted of a 2,8jtd was submitted in a recent thread, and should serve to illustrate the location. See here,

Unfortunately there may be a further complication with the 2.8idTD, in that it has a voltage regulator to supply perhaps temperature and fuel gauges. I cannot be sure as I have never owned one.

Do take note of the warning given by @the green vanper in post #2 above.

The round connector in that photo ( right hand one) I have one of them on the left hand side of the engine, right side if talking from the front. It's a 2 pin in a T configuration.

I've ordered a replacement thermostat from here ebay link and when i tinkered with the connector my thermostat gauge become unresponsive so 90% certain thats its.
As for air in the system, I had a new radiator fitted 2 months ago and the system was bled so hoping it's not air and just a dodgy sensor.

 

[Communicator]

The round connector in that photo ( right hand one) I have one of them on the left hand side of the engine, right side if talking from the front. It's a 2 pin in a T configuration.

I've ordered a replacement thermostat from here ebay link and when i tinkered with the connector my thermostat gauge become unresponsive so 90% certain thats its.
As for air in the system, I had a new radiator fitted 2 months ago and the system was bled so hoping it's not air and just a dodgy sensor.

Sorry Ebay link did not work for me, but I can confirm that on my x244 2.8jtd the combined gauge sensor, and thermostatic switch for the warning light has the connector blades in a T configuration. Thread is M16, and the hexagonal section fits into a 22mm spanner.

Last year I noticed that my gauge was going to normal immediately when switchng the ignition on. I prepared to change the sensor, but in the event, cleaning the connector contacts effected a cure. Hence I did not attempt to use the following method, which I have previously used to minimise fluid loss when changing a clutch master cylinder. I did receive a favourable report when I it suggested on another thread relating to temperature sensors.

Fill the coolant reservoir to the brim with appropriate coolant. Seal the reservoir top with thin plastic sheet, and rubber bands, or string. Prepare for a quick change of sensors, and some coolant spillage. When the old sensor is removed there should be minimum coolant loss, as any loss will be creating a vacuum at the top of the reservoir. If successful you may have to remove surplus coolant from the reservoir.

Do not attempt this on a hot engine.

 

[the green vanper]

I had a new radiator fitted 2 months ago and the system was bled

I had a similar situation, a day after the thermostat was changed and bled in my daily non-FIAT car (by a 'professionnal' in a workshop) I've noticed that the temperature gauge drops and then gets up. I've arrived back home and after a checkup I've had to add 1,5 l of the coolant...

I'm not saying it's not the sensor, I'd just check to be sure and be able to sleep calm.

 

[HLA91]

Sorry Ebay link did not work for me, but I can confirm that on my x244 2.8jtd the combined gauge sensor, and thermostatic switch for the warning light has the connector blades in a T configuration. Thread is M16, and the hexagonal section fits into a 22mm spanner.

Last year I noticed that my gauge was going to normal immediately when switchng the ignition on. I prepared to change the sensor, but in the event, cleaning the connector contacts effected a cure. Hence I did not attempt to use the following method, which I have previously used to minimise fluid loss when changing a clutch master cylinder. I did receive a favourable report when I it suggested on another thread relating to temperature sensors.

Fill the coolant reservoir to the brim with appropriate coolant. Seal the reservoir top with thin plastic sheet, and rubber bands, or string. Prepare for a quick change of sensors, and some coolant spillage. When the old sensor is removed there should be minimum coolant loss, as any loss will be creating a vacuum at the top of the reservoir. If successful you may have to remove surplus coolant from the reservoir.

Do not attempt this on a hot engine.

Apologies tried to link using my phone, edited it now, but also here https://www.ebay.co.uk/itm/173796173392

 

[HLA91]

I had a similar situation, a day after the thermostat was changed and bled in my daily non-FIAT car (by a 'professionnal' in a workshop) I've noticed that the temperature gauge drops and then gets up. I've arrived back home and after a checkup I've had to add 1,5 l of the coolant...

I'm not saying it's not the sensor, I'd just check to be sure and be able to sleep calm.

I'll be sure to grab extra coolant and keep an eye on the level, thanks for that.

 

[HLA91]

I had a similar situation, a day after the thermostat was changed and bled in my daily non-FIAT car (by a 'professionnal' in a workshop) I've noticed that the temperature gauge drops and then gets up. I've arrived back home and after a checkup I've had to add 1,5 l of the coolant...

I'm not saying it's not the sensor, I'd just check to be sure and be able to sleep calm.

You are actually making me wonder if the sensor really is playing up or if it's air, but I suppose for the price of the thermostat £13 and some coolant I can replace it and at least I've eliminated one possibility. If I still get the needle dropping off then I know it's air.

 

[the green vanper]

Start by checking the terminals of the temperature sensor. It costs nothing.

Then I'd do what @Communicator suggested: top up with coolant, seal, take out the sensor and or replace it, or if you want to test it, put a screw with the same thread (M16 x 1,5) to block the flow and check the sensor with a multimeter: put it in a pan on a hob, start heating and observe how the resistance is changing. There should be an information of the standard resistance at a certain temperature shown in the workshop manual I suppose or somewhere on the internet, but couldn't find in rapidly.

You have here a list of the sensors from other producers:

https://www.autodoc.co.uk/spares-search?keyword=500334723

Perhaps you'd be able to find technical specification / data on others than FEBI.

Bleeding the system won't probably cost you anything. Eventually you'll only have to top up the coolant. The procedure should also be described in the workshop manual (perhaps there's one available in the download section of the forum?)

 

[Communicator]

Start by checking the terminals of the temperature sensor. It costs nothing.

Then I'd do what @Communicator suggested: top up with coolant, seal, take out the sensor and or replace it, or if you want to test it, put a screw with the same thread (M16 x 1,5) to block the flow and check the sensor with a multimeter: put it in a pan on a hob, start heating and observe how the resistance is changing. There should be an information of the standard resistance at a certain temperature shown in the workshop manual I suppose or somewhere on the internet, but couldn't find in rapidly.

You have here a list of the sensors from other producers:

https://www.autodoc.co.uk/spares-search?keyword=500334723

Perhaps you'd be able to find technical specification / data on others than FEBI.

Bleeding the system won't probably cost you anything. Eventually you'll only have to top up the coolant. The procedure should also be described in the workshop manual (perhaps there's one available in the download section of the forum?)

I have been busy with other matters, but had already extracted a procedure from x244 eLearn. The procedure relates to refilling after draining the cooling system, and may need some modification. As an example you would only need to check at the bleed point, that is if you can find it. A diagram that I have not included seems to be pointing at one of the heater connections near the bulkhead. Nothing obvious on my vehicle.