Water Temp Sender Unit

[legin]

Can anyone please tell me where this unit is ? I have a 52 plate 2.2 HDi C5 SX and the temp guage is tempermental sometimes working,sometimes not.Any info. on fixes and cost much appriciated. :(

[paul.h]

Is the engine running ok ? If so then it is more likely a gauge problem than the sensor. I seem to remember something about a gauge fix that Coastline posted some time ago but can not recall what it was.

[Johndouglas]

Don't know whether this will help. Our Xsara sometimes beeped, at the same time the stop light came on and the temperature gauge went high then low. I changed the sensor in the right hand end of the head and the fault ws cured. Cost was less than a tenner.

[legin]

Is the engine running ok ? If so then it is more likely a gauge problem than the sensor. I seem to remember something about a gauge fix that Coastline posted some time ago but can not recall what it was.

Yes engine running fine,idle speed about 700 revs.Drove into work this morning and the guage rose normally then dropped to cold sector after 15 min.When the ignition is switched on the needle rises to inbetween the 2 blue lines of the cold sector so I think the guage is O.K.Is the unit located on the R.H.S. of the engine bay (when looking under the bonnet) with a small pipe runnig from it to a large water pipe? By the way my car is an automatic.Thanks for any info. :(

[paul.h]

Another possibility is a faulty thermostat.

I had a Saab where the gauge would go to normal then fall and then rise again and repeat. In the end replacement of the thermostat fixed it. Other cases where the thermostat was faulty and opened too soon, the temperature has been slow to rise unless in slow traffic but once moving again would quickly fall.

The thermostat is usually in a housing at the cylinder head end of the radiator top hose - until it opens, the hose should stay cold. I do not have a manual (such as Haynes) or the car nearby at the moment to check exactly what it looks like.

[techbod]

a good guide here is if the heat to the cabin is good and hot its probably the gauge,

do the coolant fans work when they should? if not then I agree its the coolant temp sensor or the relays/fuse if these fail you can expect over heating and we all know what happens there.

[legin]

Cabin temp is fine,not heard cooling fans come on but not been stuck in any trafic,no signs of over heating,pipes warm after 30min drive.There is movement in the guage when ignition switched on so I'm not sure if it is faulty.Thanks for all the info I'm going to have a good look at the unit once the weather is a bit drier and warmer! :rolleyes:

[techbod]

excess pressure in the pipes would indicate failed coolant fans because they kick in the fans to release the pressure. the rest of the world is suffering global warming the UK seems to have missed the boat lol.

 

of course there is always the possibility someone put too much antifreeze in to prevent freezing and in this case the engine wont heat up properly and the gauge will stay low

[legin]

I don't think its the water as this was changed before winter and the guage worked fine when it first went cold.One thing though I have just been out for a short drive and the guage worked normally,just into the white zone after 5 min,it seems the guage "fails" once the water has reached opparating temp.Any way thanks again. :rolleyes:

[techbod]

hmmm difficult to answer that and a few things could cause that but good luck anyway,

 

keep an eye on the interior temp ie: if it suddenly goes cold its a major issue.

[coastline taxis]

Not to sure on the 2.2 but iwould imaging it will be where you say. it will have a green conector with 2 wires going into it. Wouldnt think its your temp gauge mind because if it was you would have other problems as the ecu wouldnt know what temperature you engine is at. When you drained the fluid did you bleed the system properly with the 2 bleed niples

[techbod]

only way to test the coolant temp sensor is by resistance test ( the higher the resistance the colder the engine is ) if its above 250 ohms when engine is hot the temp sensor is shot,

when cold its 3k ohms plus.

[paul.h]

Had a look in the French RTA manual which covers the 2.2 hdi engine.

 

At the left hand end of the cylinder head is a large box unit and on the top of this at the front is the thermostat cover (held by 3 ? bolts) and fastened to the radiator top hose. Under this cover is the thermostat (and seal) which should start to open at 83°C (2.0 hdi is 89°C). The temperature sensor is on the left side of this box. It has 2 wires - may be worth removing the wire connector and checking if the contacts are clean and the wires are in one piece. With the connector removed the gauge should show cold (effectively very high resistance in the sensor) and with its contacts bridged (no resistance) it should show max, give a high temperature alarm and probably start the fan.

 

3 air bleed screws are shown - on the cabin heater return hose, on top of the thermostat cover, on top of the radiator.

[legin]

Had a look in the French RTA manual which covers the 2.2 hdi engine.

 

At the left hand end of the cylinder head is a large box unit and on the top of this at the front is the thermostat cover (held by 3 ? bolts) and fastened to the radiator top hose. Under this cover is the thermostat (and seal) which should start to open at 83°C (2.0 hdi is 89°C). The temperature sensor is on the left side of this box. It has 2 wires - may be worth removing the wire connector and checking if the contacts are clean and the wires are in one piece. With the connector removed the gauge should show cold (effectively very high resistance in the sensor) and with its contacts bridged (no resistance) it should show max, give a high temperature alarm and probably start the fan.

 

3 air bleed screws are shown - on the cabin heater return hose, on top of the thermostat cover, on top of the radiator.

Thanks for this,looks like I've been looking in the wrong place!So whats the small black box with a small pipe and a connector with 3 wires coming from it then? :rolleyes:

[paul.h]

Without seeing it, could this box be an oil cooler for the auto transmission ?

[legin]

Without seeing it, could this box be an oil cooler for the auto transmission ?

The box is connected to a large pipe running from under the engine cover to a small radiator in the FLH side of the bay so probable is to do with oil not water.What I did find though is a metal rod with a plastic end ,it is located just to the right(when looking at the enginefrom front/above) of the plastic engine cover.It had a small cup socket on the end which connected to a ball joint on a metal plate near what I think is the thermostat houseing.How long it has been disconected I don't know or what it does but I have reconected the 2 parts temporarorly.Any ideas.Thanks again. :rolleyes:

[paul.h]

I am sure this small radiator is the turbo intercooler which cools the air between the turbo and inlet manifold. At the engine end of this top hose should be diverter valves which either lets the air through the cooler or by-passes it through a water heated jacketted pipe. If you squeeze these air hoses you will not get any water noises.

 

I think the part with the rod is the 'capsule de commande de volet d'air' which probably translates as controlling air volume. I just put this into google and it came back with a French auto forum which google translated with posts about this air system and photos - worth a try.

[iannez]

http://i177.photobucket.com/albums/w213/iannez_photo/actuator.jpg