Activa V6 - ES9J4 Coolant Temperature

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
User avatar
DHallworth
Donor 2023
Posts: 2382
Joined: 20 Nov 2005, 17:05
Location: Glasgow
My Cars:
x 119

Activa V6 - ES9J4 Coolant Temperature

Post by DHallworth »

I've posted on this before but it still bugs me every time I drive the Activa as I was convinced it was running cold!

My temperature pin always tends to sit around 60 degrees, even after 70 miles of Yorkshire Dales roads at the Northern, and even after 200 miles home from the Northern this year.

Image

I popped out in the Activa today and after a bit of a spirited blast down the backroads I noticed the fans were running when I got home. I decided to get the Lexia out and interrogate the other temperature sensors on the car and see what they were reading. Lexia showed both of the other sensors at 92 degrees in both the Injection and Sensors screen within the parameter measurements, which is far more like what I would have expected to see.

Image

Image

I might be wrong, but I remember reading somewhere that there are 3 temperature sensors on the V6 engine, one for the ECU, one for the fans and one for the dial. Which sensor is it that runs the dial? I'm going to try replacing it with one from the spare engine I've got and see if the dial starts to read the same as the other 2 sensors do on Lexia.

David.
'98 Xantia Activa V6 :-D
'00 XM V6 Exclusive
'09 C5 2.7 HDi Exclusive
‘10 C5 3.0 HDi Exclusive
'12 C6 3.0 HDi Exclusive
'15 C4 BlueHDi Feel
elma
Posts: 3745
Joined: 13 May 2007, 02:17
Location: United Kingdom
My Cars: Undisclosed
x 287

Re: Activa V6 - ES9J4 Coolant Temperature

Post by elma »

That sounds right. I don't know your engine but for my diesels the sensor on the radiator does the fans, the one on the fuel filter does the gauge and I'm sure theres another lurking somewhere.
hattershaun
(Donor 2022)
Posts: 135
Joined: 29 Sep 2009, 12:12
Location: Bedfordshire
My Cars: C6 3.0HDi Exclusive
SM 3.0 manual 1972
DS 23 Pallas 1975
GSA Pallas C-Matic 1982
C3 Pluriel 2009
x 4

Re: Activa V6 - ES9J4 Coolant Temperature

Post by hattershaun »

David,
I wouldn't bother doing anything.
Every V6 Xantia I've had ( approx 6, so far, plus driven plenty of others), the temperature gauge always reads low.
Save you efforts for real problems!
Shaun

C6 3.0 HDi Exclusive - 2010
SM 3.0 - 1972
DS 23 Pallas - 1975
GSA Pallas C-Matic - 1982
C3 Pluriel - 2009
User avatar
xantia_v6
Forum Admin Team
Posts: 9053
Joined: 09 Nov 2005, 22:03
Location: France or NewZealand
Lexia Available: Yes
My Cars: -
1997 Citroen Xantia V6 (France)
1999 Citroen XM V6 ES9 (France)
2011 Peugeot 308 CC THP 155 (NZ)
1975 Jaguar XJ-S pre-HE (NZ)
x 825

Re: Activa V6 - ES9J4 Coolant Temperature

Post by xantia_v6 »

The gauge sensor is the blue one. On the ES9 it is mounted so that it is in contact with water going into the pump, so is seeing a mix of recirculated water at engine temperature, and cool water from the radiator. Crazy but true.
User avatar
Stickyfinger
(Donor 2016)
Posts: 10411
Joined: 28 Mar 2013, 21:05
Location: Somset my lovleee
My Cars: Xantia V6 ACTIVA 3ltr 24v Manual p1
Xm 2.1TD Ph2 Exclusive
AX, little Daffodil
SAXO White Mk1. Sally
x 1280
Contact:

Re: Activa V6 - ES9J4 Coolant Temperature

Post by Stickyfinger »

We need some number stickers for that bleeding gauge :)

Can a new sensor wire be run from one of the accurate gauges rather than the inaccurate one ? What would be the reason not to ?
Alasdair
Activa, the Moose Rider
3x C5x7 Steering racks and counting
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Re: Activa V6 - ES9J4 Coolant Temperature

Post by addo »

Why not tweak the sender wires? Is OC cold or hot? You either need to increase resistance to ground or reduce it. Play with an interrupt harness (make it) between the sender and engine loom, then wire in an appropriately tuned 20 turn cermet trim pot near the dash plugs.
User avatar
Stickyfinger
(Donor 2016)
Posts: 10411
Joined: 28 Mar 2013, 21:05
Location: Somset my lovleee
My Cars: Xantia V6 ACTIVA 3ltr 24v Manual p1
Xm 2.1TD Ph2 Exclusive
AX, little Daffodil
SAXO White Mk1. Sally
x 1280
Contact:

Re: Activa V6 - ES9J4 Coolant Temperature

Post by Stickyfinger »

Not talking to you Addo....1 point FFS....LUCKY !

:)
Alasdair
Activa, the Moose Rider
3x C5x7 Steering racks and counting
User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: Activa V6 - ES9J4 Coolant Temperature

Post by Mandrake »

DHallworth wrote:Lexia showed both of the other sensors at 92 degrees in both the Injection and Sensors screen within the parameter measurements, which is far more like what I would have expected to see.
Hi David,

Don't be fooled by the Lexia screen - the ECU (and therefore Lexia) only reads one of the three coolant temperature sensors - the green one at the front corner of the engine under the plastic cover next to the air filter box. The two different readings are "actual" and "substituted" values for the same sensor. (R and S)

Normally these two values will be the same, however if there is a sensor fault such as an open or short the actual value will show the "true" reading from the sensor (a crazy high or low value due to the fault) but the substituted value will be a "nominal" value that gets substituted when the ECU realises there is a fault.

The same applies to the air intake temperature sensor which has two readings but in reality there is only one air temperature sensor. (Yes I've looked for the "other" one just to be sure :-D ) In the case of the air temperature sensor if you unplug it the actual reading will be about -40 degrees C but the ECU realises this is a fault and substitutes +39 degrees C as a "guess" to let the engine run after a fashion. So actual is the reading that is coming from the sensor, substituted is the value that is actually used by the ECU for its fuel mixture calculations.

Regarding the other two sensors, one runs the fans and the other the dashboard gauge. On my new V6 the temperature gauge reads fairly consistently - and reads about 10-15 degrees lower than the Lexia reading typically. As others have pointed out here and elsewhere the two sensors read in very different parts of the cooling circuit so I think a reading 10 degrees or so lower on the dashboard is quite normal - typically I see about 80 or slightly less on the dashboard.

On my first V6 the dashboard temperature gauge was very quirky, like yours. For quite a while the reading would suddenly drop by 10-15 degrees in the middle of driving on the motorway then come back again, sometimes this would only last 10-30 seconds. I distinctly remember one night where I was on the motorway going up a steep incline and every time I accelerated the reading dropped 15 degrees then the moment I let my foot off the throttle the reading came back up again.

Although I never did track that problem down, IMO there could only really have been one of a couple of things causing that, either:

a) A corroded connection on the plug to the sensor or a bad wire, such that when the engine flexes on its mount with the application and removal of torque the corroded wire moves in the plug slightly causing a resistance change. This is the most likely I think, especially when the sensor for the dash is around the back of the block on the gearbox side and subject to any coolant leaks from the coolant expansion chamber...

b) The dashboard gauge sensor, which is on the back of the block may have a small pocket of air trapped near by and changes in engine RPM or inclination of the engine might move the air bubble around. I noticed the night that I had this issue that it was particularly bad when I was climbing a hill then went away when I was on the level again. If the sensor tip sits in a pocket of air not actually immersed in the water the reading will drop dramatically...

I would try cleaning the connector and/or swapping the sensor over, but also go through a proper bleeding process with a header tank to make sure there are no air pockets...
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
User avatar
xantia_v6
Forum Admin Team
Posts: 9053
Joined: 09 Nov 2005, 22:03
Location: France or NewZealand
Lexia Available: Yes
My Cars: -
1997 Citroen Xantia V6 (France)
1999 Citroen XM V6 ES9 (France)
2011 Peugeot 308 CC THP 155 (NZ)
1975 Jaguar XJ-S pre-HE (NZ)
x 825

Re: Activa V6 - ES9J4 Coolant Temperature

Post by xantia_v6 »

addo wrote:Why not tweak the sender wires? Is OC cold or hot? You either need to increase resistance to ground or reduce it. Play with an interrupt harness (make it) between the sender and engine loom, then wire in an appropriately tuned 20 turn cermet trim pot near the dash plugs.
The problem with that approach is that the guage does sometimes read the "correct" temperature, fors example, if the engine is left idling with the A/C (and thus fans) off, so the radiator is not actually cooling the coolant, then the gauge does read correctly (until the fans kick in).

The only real solutiion would be to move the sensor. Maybe even clamp it to the block.
elma
Posts: 3745
Joined: 13 May 2007, 02:17
Location: United Kingdom
My Cars: Undisclosed
x 287

Re: Activa V6 - ES9J4 Coolant Temperature

Post by elma »

Is it possible that the sensor locations actually have that large a temperature difference? It's often reported that V6 Xantias under read coolant temperature. I think I'd get investigating with a laser thermometer before I tried to repair anything.
User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: Activa V6 - ES9J4 Coolant Temperature

Post by Mandrake »

xantia_v6 wrote:
addo wrote:Why not tweak the sender wires? Is OC cold or hot? You either need to increase resistance to ground or reduce it. Play with an interrupt harness (make it) between the sender and engine loom, then wire in an appropriately tuned 20 turn cermet trim pot near the dash plugs.
The problem with that approach is that the guage does sometimes read the "correct" temperature, fors example, if the engine is left idling with the A/C (and thus fans) off, so the radiator is not actually cooling the coolant, then the gauge does read correctly (until the fans kick in).
Not only that, even if there was a fixed 10 degree offset in temperature - you can't "calibrate" an NTC or PTC type thermistor simply by adding series or parallel resistance until the reading is "correct". In trying to do so you would get the correct reading at one temperature and it would be wrong everywhere else...this is because not only is the resistance vs temperature curve non linear, you are adding or paralleling resistance which does not change in proportion to temperature.
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: Activa V6 - ES9J4 Coolant Temperature

Post by Mandrake »

elma wrote:Is it possible that the sensor locations actually have that large a temperature difference? It's often reported that V6 Xantias under read coolant temperature. I think I'd get investigating with a laser thermometer before I tried to repair anything.
Reading about 10 degrees lower on the dash is normal - the really low reading David shows on the dashboard photo is not normal, that is indicative of a sensor, sensor wiring fault, or air pocket at the sensor.

Another possibility is that remember this is a V6 Activa conversion - I believe the dashboard is the original one that came with the 2.0 TCT engine - does anyone know for sure that the calibration of the dashboard gauge itself (a given reading for a given resistance from the sensor) is the same between a TCT and V6 dashboard ?! I think we've all just kind of assumed this is the case but maybe not...
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
elma
Posts: 3745
Joined: 13 May 2007, 02:17
Location: United Kingdom
My Cars: Undisclosed
x 287

Re: Activa V6 - ES9J4 Coolant Temperature

Post by elma »

That sounds reasonable. my LDV had the same problem as it had a Metro cluster, Xud9 engine and a Ford coolant temp sensor. Was fixed using a pair of resistors in the manner that Addo described. Before I calibrated it I replaced the sensor twice and was baffled by the problem remaining. VDO do a good range of sensors with differing impedences if you know the one you need.
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Re: Activa V6 - ES9J4 Coolant Temperature

Post by addo »

According to the original post, it is wrong much of the time, albeit in a steady state.

I am proposing an approach that would make it more right when in that steady state as it apparently spends much of its time.
User avatar
CitroJim
A very naughty boy
Posts: 49534
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6163
Contact:

Re: Activa V6 - ES9J4 Coolant Temperature

Post by CitroJim »

Mandrake wrote:Another possibility is that remember this is a V6 Activa conversion - I believe the dashboard is the original one that came with the 2.0 TCT engine - does anyone know for sure that the calibration of the dashboard gauge itself (a given reading for a given resistance from the sensor) is the same between a TCT and V6 dashboard ?! I think we've all just kind of assumed this is the case but maybe not...
That's actually a good point Simon... I could have tested that but although I have a spare Activa dash - from a TCT, I no longer have any spare V6 ones...
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
Post Reply