Official blog of 'War Horse' (My Xantia HDi). It lives to fight another day!

[Rhothgar]

Aahhhh. Yes. Core plugs!

Just done an update on my previous coolant heater post if there is anything you can add to that that would be great.

I’ve took ECU out to strip down but might just schlep it back in and pull the fan maxi fuses to see if that allows circuit to come alive.

Just really need to understand the correct parameters for functioning of this system.

[Rhothgar]

Here is the video of the coolant heater issue.

Weather was cold and snowing that day. 31/03/2022

CONTAINS FRUITY LANGUAGE.

Spoiler: show

https://1drv.ms/v/c/7d6925d9fc9200bf/UQ ... 8MtH8Fq2IU

[Rhothgar]

Well. That's another thing ticked off the list.

I say fixed but I managed to snap the stud off one of the glow plugs trying to undo it. Nut came off the other day fine and went back on. Probably tried to undo it too fast.

So after all that cogitating (and learning new stuff about diagnostics) it turns out that the nut holding the terminal of the earth wire to the heater block was not fully tightened. In fact, it's safe to say it was loose thus causing high resistance in the circuit at that point.

The effectiveness of the heater block with 3 glow plugs is obviously down until I can get a suitable replacement. I believe it is an GN984. I have a GN909 spare which is only an 11V glow plug and it is slightly longer so I won't risk it.

At full capacity, the system should provide 784W of energy with the alternator providing 14V at 14A for each plug. This would take 3 minutes 56 seconds assuming there is a litre of water (from heater block to and including the heater matrix) to be heated from 6 deg C to 50 degC and certainly more than 4 minutes 30 seconds if running at 12V and 14A.

In real terms, it's probably quicker to warm the cabin by driving and of course with the heater matrix being such a big surface area it is very efficient at dispersing the heat generated quite quickly.

Does anyone with a 2.0HDi in any model of older Citroen enjoy fast cabin temps in winter - probably not but I would be interested to hear.

[Rhothgar]

Just an update on the real War Horse.

IRO the photo of my Gramps' tank.

I did think the attire was odd but these are German soldiers. The War Histories kept at Bovington are at best, propaganda, designed to boost moral. This tank has clearly be captured by the Germans unless they just stopped by for a photo after it broke down. The Lewis Gun lying in the doorway is enough to convince me that this was Gramps' tank. The War Histories declare that this tank was taken to Guedecourt I think it was for repair and then back into service (possibly under a different number - which would make sense if the initial written history of the day said it was destroyed by the Tank Commander - it logically couldn't re-appear with the same number, could it?).

As this was frontline on the day it broke down, it makes sense that the Germans advanced a little more, possibly had this photo taken to boost moral back home and then went back to fighting.

One thing that isn't mentioned in the War Histories and if, as I believe, they are propaganda then it wouldn't be written down. I was told my grandfather (not by him directly as he never really said much about it) was that he was taken as a prisoner of war and that they looked after him really well. He was wounded that day so maybe none of them were extricated as the War History Diaries state. It's a real shame that I will perhaps never find out the truth of the matter.

[Rhothgar]

Some of you may know that I have been getting into ECU work of late.

I bought a new full chip Lexia a couple of weeks ago and it will not erase codes from the ECU. There are non-permanent faults. My diagnostic mate says that permanent faults will not erase until the underlying fault is fixed.

Here I only have temporary faults so what is the issue?

My latest thoughts are that I need to look at the loom in the rear footwell where my mate accidentally burnt through some wires last year when welding. He effected a repair so I will check that.

Also the pin on the OBD port that pushes back in the connector is Pin 5 which is signal ground. At first, I thought that this might be the issue BUT that wire grounds at MC40 which is in the front footwell so I will check that too. What I cannot get my head around is that the Lexia looks to be reading pre-existing faults. Those faults look to be old, BECAUSE:-

a) The NTC resistor in the nearside mirror was faulty. Recording between 29-40degC on 3 August 2023.
b) That mirror got smashed off in July 2025. Therefore, NTC resistor was repaired!

SO why are they are not deleting?

Earth MC41 in the front footwell is where the fuel pump earths. I have a P0230 DTC (date unknown) where it states the voltage is only 6.9 Volts. Fuel pump is actually operating correctly BUT it does make me wonder if there is a short to voltage and that perhaps there may be a short to the earth wire that grounds the signal at the OBD port and therefore will not allow codes to be erased?

I had a tinker with the original ECU with the corroded Pin 86 yesterday. Powered it up on the bench (mate's kitchen table) and read the fault codes from it. There are configuration errors on that (P1613) maybe because the immo chip is actually in the current ECU. I'll post a video up later to show this in case it is of interest to anything.

Appparently the DTC registers are written to the immo chip amongst other things. Could it be that they are now hardcoded? Do I need to re-solder the chip back into its original ECU and delete the codes? Time will tell. That is a job for another day after more research.

[CitroJim]

Interesting stuff Roger... Keep us all posted

[Stickyfinger]

Did some work/digging on that Mk IV tank photo

Defo in German hands.....as such I would bet it is a "looks like my tank" type photo added to his box of memories after the war etc, rather being his tank itself. Crew at the time would VERY rarely have a photo of THEIR tank as photography was still very rare, not really many point and shoot cameras at the time

I worked the photo....I don't see 80-21 or 80-22.....may be 8002 ?

https://sites.google.com/site/landships ... /2001-2099

Having a non stenciled/no white number in that position is also very "non-standard" (changes happen however) ..... but is the very unlikely chance a German photograph was found by your relative that long ago ....big questions on that.
Or did YOU find the photo ?

[Rhothgar]

Did some work/digging on that Mk IV tank photo

Defo in German hands.....as such I would bet it is a "looks like my tank" type photo added to his box of memories after the war etc, rather being his tank itself. Crew at the time would VERY rarely have a photo of THEIR tank as photography was still very rare, not really many point and shoot cameras at the time

I worked the photo....I don't see 80-21 or 80-22.....may be 8002 ?


https://sites.google.com/site/landships ... /2001-2099

Having a non stenciled/no white number in that position is also very "non-standard" (changes happen however) ..... but is the very unlikely chance a German photograph was found by your relative that long ago ....big questions on that.
Or did YOU find the photo ?

It's definitely a stretch that it is 8021 but there does seem to be a little 'leg' on the third number with a near vertical attaching it.

This photo was not in my grandfather's box of memories. It was provided by a member of the Landships forum.

8002 was at Velu Wood on 21/03/2018 holed up ready for a 4am start from memory. I've not been able to cross reference any more information about 8021 or whether he would have been seconded to another tank on a particular day as there is such much documentation in the archives at Bovington and time ticks away fast. There was also a lot lost in The Blitz when the records were kept in London.

I do know that this was the second time his tank had broken down on the day it was allegedly destroyed where it stood. I cannot say for sure but a job was a job. I am not sure tank crew would be allowed a day off during an important planned advancement if their tank had broken down. They may well have got involved in repairing or perhaps taken a spare tank out for the day...

I am clear that he was with Captain A. L. Phillips. I have a letter from him commending my grandfather for his service and he used to send him money from Canada every year. Maybe he saved his life. I'm just supposing but it is a big commitment to send someone money every year for no reason. I'd love to be able to trace descendants of Captain Phillips.

EDIT:

You may note that he was at Fontaine on 23/11/2017 which is on the battle line near Flesquieres where 'Deborah' the tank that featured in Guy Martin's documentary was ditched and housed.

[MattBLancs]

I believe it is an GN984.
...
Does anyone with a 2.0HDi in any model of older Citroen enjoy fast cabin temps in winter - probably not but I would be interested to hear.

Not an older Citroen but my 306 with DW10 HDi had the same 4x glow plug heater (though top of gearbox mounted rather than on the bulkhead) heater was decent, did take a bit to generate some warmth.
Can't remember if I tested the plugs (continuity - I didn't want to do the usual "jump leads and hold it on the battery" test as was unsure if it was rated to run in air (air being significantly lower specific heat capacity than water)) I remember cleaning up the terminals and brass terminal "links".

Anyway, I had a quick search for Beru GN984, here's the spec according to Autodoc:

←

Item details

Tightening torque from [Nm] 15
Tightening torque to [Nm] 25
Fitting Depth [mm] 30
Failure Moment [Nm] 45
Current Strength [A] 14
Glow Plug Design: Pencil-type Glow Plug, after-glow capable
Spanner Size 12 mm
Tightening Torque [Nm] 22
Overall Length [mm] 67
Thread size M12x1,25
Cone Pitch 63
Connector type M5/3 Nm
Voltage [V] 12
Manufacturer part number
Manufacturer BERU GN984
EAN number 4014427047629
Trade numbers BERU 0 100 226 253, BERU 0100226253, BERU E2519226253A1, BERU GN 984

£10.49 each at present:
BERU Glow Plug, auxiliary heater = AUTODOC https://m.autodoc.co.uk/beru/991185

[Rhothgar]

Not an older Citroen but my 306 with DW10 HDi had the same 4x glow plug heater (though top of gearbox mounted rather than on the bulkhead) heater was decent, did take a bit to generate some warmth.
Can't remember if I tested the plugs (continuity - I didn't want to do the usual "jump leads and hold it on the battery" test as was unsure if it was rated to run in air (air being significantly lower specific heat capacity than water)) I remember cleaning up the terminals and brass terminal "links".

Anyway, I had a quick search for Beru GN984, here's the spec according to Autodoc:

←

Item details

Tightening torque from [Nm] 15
Tightening torque to [Nm] 25
Fitting Depth [mm] 30
Failure Moment [Nm] 45
Current Strength [A] 14
Glow Plug Design: Pencil-type Glow Plug, after-glow capable
Spanner Size 12 mm
Tightening Torque [Nm] 22
Overall Length [mm] 67
Thread size M12x1,25
Cone Pitch 63
Connector type M5/3 Nm
Voltage [V] 12
Manufacturer part number
Manufacturer BERU GN984
EAN number 4014427047629
Trade numbers BERU 0 100 226 253, BERU 0100226253, BERU E2519226253A1, BERU GN 984

£10.49 each at present:
BERU Glow Plug, auxiliary heater = AUTODOC https://m.autodoc.co.uk/beru/991185

That’s a great location for the auxiliary heater Matt although a nice stretch of my back muscles probably helped my back mobility.

I’m really surprised you were able to find the GN984. I’m sure I could not find any at the time hence going for the Lucas ones. BARGAIN TOO! See my post in For sale, Wanted.

Yes. They are stubby little things.

I really do need to get the air con working again because that is the biggest single factor in the screen not clearing well. It still blows my mind that the engine fans come on when the air con comes on. Remind me of the purpose of that again!

I might just well somehow wire in a timer circuit on that line so that they come on for 5 minutes unless the air temperature is above 5 deg C. Splice into the air mass meter signal or something.

[MattBLancs]

I’m really surprised you were able to find the GN984. I’m sure I could not find any at the time hence going for the Lucas ones. BARGAIN TOO! See my post in For sale, Wanted.

Yes. They are stubby little things.

Yes I was pleased to find them! I think I came across them a while back , but thankfully Google of "gn984" directed me to Autodoc and there they were again!

I really do need to get the air con working again because that is the biggest single factor in the screen not clearing well. It still blows my mind that the engine fans come on when the air con comes on. Remind me of the purpose of that again!

Running air conditioning drys the air, (airborne moisture condenses out on the coil in the heater box)
Dry(er) air greatly improves demist function (forced evaporation)

AC system needs a flow of cooler air across the evaporator coil mounted in front of the coolant radiator (to which it can reject heat from the refrigerant)

Movement of air = switch the fans on.

Don't forget cold engine = thermostat shut, so air movement over radiator should only be chilling the coolant sat static in the radiator (i.e. shouldn't negatively affect engine warm up)

[Rhothgar]

Don't forget cold engine = thermostat shut, so air movement over radiator should only be chilling the coolant sat static in the radiator (i.e. shouldn't negatively affect engine warm up)

That’s exactly the answer I was looking for. Thank you Matt. Even with your descriptive precursor to the above paragraph I have isolated it still seems a daft idea to have the fans on at first start.

Obviously the thermostat is going to open slower and engine warm-up takes longer meaning less efficient.

This might explain why I am not getting the MPG I would expect.

As CitroJim says, the HDi are so efficient they are slow to heat up. I wish the S1 had the same acceleration! It would be more fun.

[myglaren]

Obviously the thermostat is going to open slower and engine warm-up takes longer meaning less efficient.

I'd think that it would be insignificant. The fan will only cool the radiator to the ambient temperature, i.e probably no change. The cooling will only happen when the thermostat opens, which will be incremental and not at all until the engine reaches the thermostat's design temperature, around 80° for initial opening.
The coolant should only flow through the engine and heater matrix until that temperature is achieved.

[MattBLancs]

Yep, myglaren and I are have same thoughts, you'll have slightly cooler radiator water but the coolant looping around the
engine block --> (glow plug auxiliary heater) --> heater matrix "short circuit" will be isolated from that by shut thermostat.

Another warm up device question: does your HDi have EGR and if so, is it water cooled?
Early DW10 HDi (e.g. my 306's 90 bhp engine) had no EGR cooler,
Later ones (e.g the 110 bhp inlet manifold off a dispatch van I got) had the EGR heat exchanger strapped to top of the manifold.

When the engine's cold that's effectively a "exhaust gas powered coolant heater"

[Rhothgar]

Yep, myglaren and I are have same thoughts, you'll have slightly cooler radiator water but the coolant looping around the
engine block --> (glow plug auxiliary heater) --> heater matrix "short circuit" will be isolated from that by shut thermostat.

Another warm up device question: does your HDi have EGR and if so, is it water cooled?
Early DW10 HDi (e.g. my 306's 90 bhp engine) had no EGR cooler,
Later ones (e.g the 110 bhp inlet manifold off a dispatch van I got) had the EGR heat exchanger strapped to top of the manifold.

When the engine's cold that's effectively a "exhaust gas powered coolant heater"

That's an interesting question. I'd imagine it has but I am not 100% sure. I have a feeling it isn't. I have a feeling it is on studs on the manifold and from memory it doesn't look as though the nuts will undo as the shank of one of the studs is probably half the thickness it should be. Might be a manifold off and helicoil job which is why I have been avoiding replacing it or decoking it.

I do recall the drawings of the rear of the engine in one of the Factory Manuals does not represent one I have. This probably explains why. I will have the manual for an earlier year perhaps.